OSPF

This chapter provides information about configuring the Open Shortest Path First (OSPF) protocol.

Topics in this chapter include:

Overview of OSPF

OSPF (Open Shortest Path First) is an interior gateway protocol (IGP) that is used within large autonomous systems (ASs). An autonomous system is a group of networks and network equipment under a common administration. OSPF is a link-state protocol; each router maintains an identical database (called the link-state database, topological database, or routing information database [RIB]) of the AS, including information about the local state of each router (for example, its usable interfaces and reachable neighbors).

OSPF-TE (OSPF with traffic engineering extensions) is used to advertise reachability information and traffic engineering information such as bandwidth. OSPF routers exchange status, cost, and other relevant interface information with neighboring routers. The information exchange enables all participating routers to establish their link-state database.

OSPF uses a cost metric that represents the status of the link and the bandwidth of the interface in an algorithm to determine the best route to a destination. The algorithm used is called the SPF (shortest path first) or Dijkstra algorithm. Path selection is based on lowest cost, which might not necessarily be the shortest route but is the best route in regards to bandwidth. Each router applies the algorithm to calculate the shortest path to each destination in the network.

When the best route to a particular destination is determined, the route information is sent to the routing table manager (RTM). The RTM may contain more than one best route to a destination from multiple protocols. Because metrics from different protocols are not comparable, the RTM uses preference to select the best route. The route with the lowest preference value is selected. For more information, see Configuring route preferences.

The best routes from the RTM are then added to the forwarding table (also known as the forwarding database [or FIB]). All forwarding decisions are based on the information in the forwarding database.

The forwarding (or dropping) of packets is controlled by filters applied to the interface and route policies applied to the OSPF protocol. See the 7705 SAR Router Configuration Guide for information about filters and route policies.

The 7705 SAR implementation of OSPF conforms to OSPF Version 2 specifications presented in RFC 2328, OSPF Version 2 and OSPF Version 3 specifications presented in RFC 2740, OSPF for IPv6. Routers running OSPF can be enabled with minimal configuration. All default and command parameters can be modified.

Changes between OSPF for IPv4 and OSPFv3 for IPv6 include the following.

  • Addressing semantics have been removed from OSPF packets and the basic link-state advertisements (LSAs). New LSAs have been created to carry IPv6 addresses and prefixes.

  • OSPFv3 runs on a per-link basis, instead of on a per-IP-subnet basis.

  • Flooding scope for LSAs has been generalized.

  • Unlike OSPFv2, OSPFv3 authentication relies on IPV6's authentication header and encapsulating security payload.

  • Most packets in OSPF for IPv6 are almost as compact as those in OSPF for IPv4, even with the larger IPv6 addresses.

  • Most field and packet-size limitations present in OSPF for IPv4 have been relaxed.

  • Option handling has been made more flexible.

The following major OSPF features are supported:

  • areas – backbone, super backbone, stub, and not-so-stubby areas (NSSAs)

  • virtual links

  • neighbors and adjacencies

  • link-state advertisements (LSAs)

  • metrics

  • authentication (OSPFv2 only)

  • route redistribution and summarization

  • OSPF traffic engineering (TE) extensions (to track and advertise available bandwidth (OSPFv2 only)–used by MPLS traffic engineering; that is, RSVP-TE)

OSPF areas

An autonomous system can be divided into areas, with each area containing a group of networks. An area’s topology is concealed from the rest of the AS, which significantly reduces OSPF protocol traffic (LSA updates), simplifies the network topology, and simplifies the routing table by populating it with summarized routes instead of exact routes on each router. This decrease in LSA updates, link-state database size, and CPU time, all required for OSPF route calculations, results in a decrease in route calculation time.

All routers in an area have identical link-state databases for that area.

Areas within the same AS are linked to each other via area border routers (ABRs). An ABR is a router that belongs to, and passes reachability information between, more than one OSPF area. An ABR maintains a separate topological database for each area it is connected to.

Routing in the AS takes place on two levels, depending on whether the source and destination of a packet reside in the same area (intra-area routing) or different areas (inter-area routing). In intra-area routing, the packet is routed solely on information obtained within the area; that is, routing updates are only passed within the area. In inter-area routing, routing updates are passed between areas.

External routes refer to routing updates passed from another routing protocol into the OSPF domain.

Routers that pass information between an OSPF routing domain and a non-OSPF network are called autonomous system boundary routers (ASBRs).

Backbone area

Every OSPF system requires a backbone area. The OSPF backbone area is uniquely identified as area 0 and uses the area ID 0.0.0.0. All other areas must be connected to the backbone area, either physically or logically. The backbone distributes routing information between areas. If it is not practical or possible to connect an area to the backbone (see area 0.0.0.5 in the following figure), the ABRs (routers Y and Z in the figure) must be connected via a virtual link. The two ABRs form a point-to-point-like adjacency across the transit area (area 0.0.0.4).

Figure 1. Backbone area

Super backbone area

Note: The super backbone is only supported under the VPRN OSPF context.

The 7705 SAR supports a version of the BGP/OSPF interaction procedures as defined in RFC 4577, OSPF as the Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Private Networks (VPNs) (support for basic OSPF at PE-CE links), to provide an MPLS VPN super backbone area. The BGP/OSPF interaction procedures that are supported as part of the super backbone include the following:

  • loop prevention

  • handling LSAs received from the CE

  • sham links

  • managing VPN-IPv4 routes received by BGP

The MPLS VPN super backbone functions like an additional layer of hierarchy in OSPF. The PE routers that connect the OSPF areas to the super backbone function as OSPF ABRs in the OSPF areas to which they are attached. In order to achieve full compatibility, the PE routers can also function as ASBRs in NSSAs.

VPRN routes can be distributed among PE routers by BGP. If a PE router uses OSPF to distribute routes to a CE router, the standard procedures governing BGP/OSPF interactions cause routes from one site to be delivered to another site in type 5 LSAs as AS-external routes.

The PE routers insert inter-area routes from other areas into the area where a CE router is present. The CE routers are not involved at any level, nor are they aware of the super backbone or of other OSPF areas present beyond the MPLS VPN super backbone.

The CE always assumes that the PE is an ABR:

  • If the CE is in the backbone, then the CE assumes that the PE is an ABR linking one or more areas to the backbone.

  • If the CE is not in the backbone, the CE assumes that the backbone is on the other side of the PE.

  • Therefore, the super backbone looks like another area to the CE.

Figure 2. PE routers connected to an MPLS VPN super backbone

In PE routers connected to an MPLS VPN super backbone, the PE routers are connected to the MPLS VPN super backbone. In order to be able to distinguish if two OSPF instances are the same and require type 3 LSAs to be generated or if they are two separate routing instances that require type 5 external LSAs to be generated, the concept of a domain ID is used.

The domain ID is carried with the MP-BGP update message and indicates the source OSPF domain. When the routes are being redistributed into the same OSPF domain, the concepts of a super backbone described previously are applied and type 3 LSAs are generated. If the OSPF domain does not match the domain ID, the route type will be external.

When configuring the super backbone, all destinations learned by PEs with matching domain IDs become inter-area routes.

When configuring sham links, the links become intra-area routes if they are in the same area.

Sham link

A sham link is a logical PE-to-PE unnumbered point-to-point interface that rides over the PE-to-PE transport tunnel. A sham link can be associated with any area and can appear as an intra-area link to CE routers attached to different PEs in a VPN.

Figure 3. Sham link

In Sham link, the link between CE routers CE-3 and CE-4 (shown in red) is a low-speed OC-3/STM-1 link. Because the link establishes an intra-area route connection (backdoor link) between the CE-3 and CE-4 routers, a potential high-speed connection between PE routers PE-1 and PE-2 will not be utilized because OSPF always prefers intra-area links over inter-area links. Even as part of a super backbone configuration, the link between the PE routers is regarded as an inter-area connection.

To prevent the backdoor link from always being the preferred path, a sham link (shown in green) is also constructed as an inter-area link between PE routers. A normal OSPF adjacency is formed and the link-state database is exchanged across the MPLS VPN. As a result, the desired intra-area connectivity is created, and the cost of the sham link and backdoor link can be managed so that the backdoor link becomes a standby link and is used only if the sham link fails.

Note: A sham link is only required with an MPLS VPN configuration if a backdoor link is present.
Implementing the OSPF super backbone

With the OSPF super backbone architecture, the continuity of OSPF routing is preserved:

  • The OSPF intra-area type 1 and type 2 LSAs advertised by the CE are inserted into the MPLS VPN super backbone by redistributing the OSPF route into MP-BGP by the PE adjacent to the CE.

  • The MP-BGP route is propagated to other PE routers and inserted as an OSPF route into other OSPF areas. Because the PEs across the super backbone always act as ABRs, they will generate inter-area route OSPF summary type 3 LSAs.

  • The inter-area route can now be propagated to other OSPF areas by other customer-owned ABRs within the customer site.

  • Customer area 0 (backbone) routes appear as type 3 LSAs when carried across the MPLS VRN using MP-BGP even if the customer area remains area 0.

A BGP extended community (OSPF domain ID) provides the source domain of the route. This domain ID is not carried by OSPF but is carried by MP-BGP as an extended community attribute.

If the configured extended community value matches the receiving OSPF domain, the OSPF super backbone is implemented.

From a BGP perspective, the cost is copied into the MED attribute. For information about the MED attribute, see MED attribute.

Loop avoidance

If a route sent from a PE router to a CE router is then be received by another PE router from one of its own CE routers, routing loops may occur. RFC 4577 specifies several methods of loop avoidance.

DN bit

When a type 3 LSA is sent from a PE router to a CE router, the DN bit in the LSA options field is set. This ensures that if any CE router sends the type 3 LSA to a PE router, the PE router does not redistribute it.

VPN route tag

If a particular VRF in a PE is associated with OSPF, then by default the VRF is configured with a special OSPF route tag value called the VPN route tag. This route tag is included in the type 5 LSAs that the PE originates and sends to any of the attached CEs. The configuration and inclusion of the VPN route tag is required for backward compatibility with implementations that do not set the DN bit in type 5 LSAs.

Area border router

Areas within the same AS are linked to each other via ABRs. An ABR is a router that belongs to, and passes reachability information between, more than one area. An ABR maintains a separate topological database for each area it is connected to.

A base router OSPF instance assumes an ABR role if it is actively attached to two or more different areas with at least one operationally up interface, and one of the attached areas is area 0.

If an ABR has an area 0 adjacency, it always calculates inter-area routes using only backbone summary LSAs. A router connected to multiple areas without an area 0 adjacency calculates inter-area routes using summary LSAs from all actively attached areas. This functionality helps to avoid packet loss in some inter-area scenarios.

Stub area

A stub area is a designated area that does not allow external route advertisements and cannot contain ASBRs. Virtual links cannot pass through stub areas.

To route to external destinations, the ABR of the stub area advertises a single default route into the stub area (0.0.0.0). A default route is the network route used by a router when no other known route exists for a given IP packet’s destination address. All packets for destinations not known by the router’s routing table are sent to the default route and out to the network.

This feature reduces the size of the router’s database and reduces OSPF protocol traffic, memory usage, and CPU route calculation time.

In Backbone area, areas 0.0.0.1, 0.0.0.2 and 0.0.0.5 could be configured as stub areas.

Not-so-stubby area

Another OSPF area type is called a not-so-stubby area (NSSA). NSSAs are similar to stub areas except that limited importing of external routes is allowed. Only routes within the AS are advertised. External routes learned by OSPF routers in the NSSA area are advertised as type 7 LSAs (external route advertisements only within the NSSA area) and are translated by ABRs into type 5 external route advertisements for distribution into other areas of the OSPF domain.

For information about LSA types, see Link-state advertisements.

An NSSA area cannot be designated as the transit area of a virtual link.

In Backbone area, area 0.0.0.3 could be configured as an NSSA area.

Virtual links

The backbone area in an OSPF AS must be contiguous and all other areas must be directly connected to the backbone area via an ABR. If it is not practical or possible to physically connect an area to the backbone, virtual links can be used to connect to the backbone through a non-backbone area.

A virtual link functions as a point-to-point link that passes through a transit area. Backbone area depicts routers Y and Z as the start and end points of the virtual link while area 0.0.0.4 is the transit area. In order to configure virtual links, the router must be an ABR. Virtual links are identified by the router ID of the other endpoint, which is another ABR.

These two endpoint routers must be attached to a common area, called the transit area. The area through which the virtual link passes must have full routing information.

Transit areas pass traffic from an area adjacent to the backbone or to another area. The traffic does not originate or terminate in the transit area. The transit area cannot be a stub area or an NSSA area.

Virtual links are part of the backbone and function as if they were unnumbered point-to-point networks between the two routers. A virtual link uses the intra-area routing of its transit area to forward packets. Virtual links are brought up and down through the building of the shortest-path trees for the transit area.

Neighbors and adjacencies

A router uses the OSPF Hello protocol to discover neighbors. Neighbors are routers that interface to a common network. In a broadcast-supported topology, one router sends Hello packets to a multicast address and receives Hello packets in return. Unicast Hello packets are used in non-broadcast topologies.

The neighbors then attempt to form adjacencies by exchanging link-state information with the goal of having identical link-state databases. When the link-state databases of two neighbors are synchronized, they are considered to be adjacent.

Designated routers and backup designated routers

In multi-access broadcast networks, such as Ethernet networks, with at least two attached routers, a designated router and a backup designated router can be elected. The concept of a designated router was developed in order to avoid the formation of adjacencies between all attached routers. Without a designated router, the area would be flooded with LSAs – a router would send LSAs to all its adjacent neighbors, and each in turn would send LSAs to all their neighbors, and so on. This would create multiple copies of the same LSA on the same link.

The designated router reduces the number of adjacencies required because each router forms an adjacency only with the designated router and backup designated router. Only the designated router sends LSAs in multicast format to the rest of the network, reducing the amount of routing protocol traffic and the size of the link-state database. If the designated router fails, the backup designated router becomes active.

The designated router is automatically elected based on priority – the router with the highest priority becomes the designated router and the router with the second-highest priority becomes the backup. If two routers have the same priority, the one with the highest router ID wins.

A router with a priority set to 0 can never become a designated router.

After a designated router is elected, it begins sending Hello packets to all other attached routers in order to form adjacencies.

Note:

  • In point-to-point networks, where a single pair of routers are connected, no designated or backup designated router is elected. An adjacency must be formed with the neighbor router.

  • To significantly improve adjacency forming and network convergence, a network should be configured as point-to-point if only two routers are connected, even if the network is a broadcast media such as Ethernet.

Link-state advertisements

Link-state advertisements (LSAs) describe the state of a router or network, including router interfaces and adjacency states. Each LSA is flooded throughout an area. The collection of LSAs from all routers and networks form the protocol’s link-state (or topological) database.

The distribution of topology database updates takes place along adjacencies. A router sends LSAs to advertise its state according to the configured interval and when the router’s state changes. These packets include information about the router's adjacencies, which allows detection of non-operational routes.

When a router discovers a routing table change or detects a change in the network, link-state information is advertised to other routers to maintain identical routing tables. Router adjacencies are reflected in the contents of its link-state advertisements. The relationship between adjacencies and the link states allow the protocol to detect non-operating routers. Link-state advertisements flood the area. The flooding mechanism ensures that all routers in an area have the same topological database. The database consists of the collection of LSAs received from each router belonging to the area.

OSPF sends only the changed information, not the whole topology information or whole link-state database, when a change takes place. From the topological database, each router constructs a tree of shortest paths with itself as root (that is, runs the Dijkstra algorithm). OSPF distributes routing information between routers belonging to a single AS.

The following table lists the types of LSAs generated by routers.

Table 1. LSA types

LSA

Definition

Type 1 - Router

Router link advertisements generated by each internal router for each area it belongs to

LSAs are flooded only in the area in which they were originated

Router LSAs list all the router’s links and the state and cost of the links

Type 2 - Network

Network link advertisements generated by designated routers describing the set of routers attached to a particular network

LSAs are flooded only in the area of the router that originated them

Network LSAs list all attached routers, including the designated router

Type 3 - Network Summary

Summary link advertisements generated by ABRs describing inter-area routes (areas within the AS but outside the area they are sent into)

LSAs let internal routers know which destinations can be reached by the ABR

LSAs are sent in both directions – into a non-zero area and into the backbone area

Type 4 - ASBR Summary

Summary link advertisements generated by ABRs indicating the location of ASBRs

An ABR generates a type 4 LSA after receiving a type 5 LSA from an ASBR

Type 5 - AS External

Generated by an ASBR and describes destinations external to the AS or a default route external to the AS

LSAs are flooded to all areas except stub areas

Type 6 - Group membership

Group membership link entry generated by multicast OSPF routers

Not applicable in this release

Type 7 - NSSA External

NSSA external routes generated by an ASBR and used by the NSSA to import external routes into a stub area

LSAs are flooded only to the NSSA

The ABR converts type 7 LSAs into type 5 LSAs before flooding them into the backbone, where they are then flooded to all areas except stub areas

Metrics

In OSPF, all interfaces have a cost value or routing metric used in the OSPF link-state calculation. A metric value is configured based on hop count, bandwidth, or other parameters, to compare different paths through an AS. OSPF uses cost values to determine the best path to a particular destination – the lower the cost value, the more likely the interface will be used to forward data traffic.

Costs are also associated with externally derived routing data, such as those routes learned from an Exterior Gateway Protocol (EGP), for example, BGP, and are passed transparently throughout the AS. This data is kept separate from the OSPF protocol’s link-state data. Each external route can be tagged by the advertising router, enabling the passing of more information between routers on the boundaries of the AS.

Authentication

Protocol authentication protects against malicious attacks on the communications between routing protocol neighbors. These attacks could either disrupt communications or inject incorrect routing information into the system’s routing table. The use of authentication keys can help to protect routing protocols from these types of attacks.

All OSPF protocol exchanges can be authenticated. This guarantees that only trusted routers can participate in autonomous system routing.

Authentication must be explicitly configured and can be done using two separate mechanisms:

  • configuration of an explicit authentication key and algorithm using the authentication-key and authentication-type commands

  • configuration of an authentication keychain using the auth-keychain command

Either the authentication-key command or the auth-keychain command can be used by OSPF, but both cannot be supported at the same time. If both commands are configured, the auth-keychain configuration will be applied and the authentication-key command will be ignored.

By default, authentication is not enabled on an interface.

Authentication key

For explicit authentication keys, OSPF supports plaintext (simple password) and Message Digest 5 (MD5) authentication.

When authentication is enabled on a link, a text string password must be configured. Neighbor OSPF routers must supply the password in all OSPF packets they send to an interface.

Plaintext authentication includes the password in each OSPF packet sent on a link.

MD5 authentication is more secure than plaintext authentication. MD5 authentication uses the password as an encryption key. Routers in the same routing domain must be configured with the same key. When the MD5 hashing algorithm is used for authentication, MD5 is used to verify data integrity by creating a 128-bit message digest from the data input that is included in each packet. The packet is transmitted to the router neighbor and can only be decrypted if the neighbor has the correct password.

The following authentication commands can be configured at the interface level and the virtual link level:

  • authentication-key – configures the password used by the OSPF interface or virtual link to verify OSPF protocol packets

  • authentication-type – enables authentication and specifies the type of authentication to be used on the interface or virtual link, either password or message digest

  • message-digest-key – used when the message-digest keyword is selected in the authentication-type command

Authentication keychains

The keychain mechanism allows for the creation of keys used to authenticate OSPF communications. Each keychain entry defines the authentication attributes to be used in authenticating OSPF messages from remote peers or neighbors; the entry must include at least one key entry to be valid. The keychain mechanism also allows authentication keys to be changed without affecting the state of the OSPF adjacencies and supports stronger authentication algorithms than plaintext and MD5.

Keychains are configured in the config>system>security>keychain context. For more information about configuring keychains, see the 7705 SAR System Management Guide, ‟TCP Enhanced Authentication and Keychain Authentication”.

The keychain is then associated with an OSPF interface or virtual link with the auth-keychain command.

For a key entry to be valid, it must include a valid key, the current system clock value must be within the begin and end time of the key entry, and the algorithm specified must be supported by OSPF.

OSPF supports the following authentication algorithms:

  • clear text password

  • MD5

  • HMAC-SHA-1-96

  • HMAC-SHA-1

  • HMAC-SHA-256

Keychain errors are handled as follows:

  • If a keychain exists but there are no active key entries with an authentication type that matches the type supported by OSPF, inbound OSPF packets will not be authenticated and will be discarded and no outbound OSPF packets will be sent.

  • If a keychain exists but the last key entry has expired, a log entry will be raised indicating that all keychain entries have expired.

    OSPF requires that the protocol continue to authenticate inbound and outbound traffic using the last valid authentication key.

Route redistribution and summarization

Route redistribution is the taking of routes from one protocol and sending them to another protocol. The 7705 SAR supports the redistribution of static routes into OSPF. These routes are advertised as type 5 or type 7 LSAs (external routes) and are included in each router’s link-state database.

Route redistribution involves the use of routing policies. For information about routing policies, see the 7705 SAR Router Configuration Guide, ‟Route Policies”.

Route summarization allows an ABR or ASBR to summarize routes with the same prefix into a single route and distribute it to other areas. Routes redistributed into OSPF from static routes can also be summarized.

Route summarization reduces the amount of routing information across areas and the size of routing tables on the routers, thus improving the calculation speed of the routers.

OSPF-TE extensions

OSPF traffic engineering (TE) extensions enable the 7705 SAR to include traffic engineering information in the algorithm in order to calculate the best route to a destination. The traffic information includes:

  • maximum reservable bandwidth

  • unreserved bandwidth

  • available bandwidth

Unnumbered interfaces

OSPF supports unnumbered point-to-point interfaces with both Ethernet and PPP encapsulations.

Unnumbered interfaces borrow the address from other interfaces such as system, loopback, or another numbered interface, and use it as the source IP address for packets originated from the interface.

This feature supports both dynamic and static ARP for unnumbered interfaces to allow interworking with unnumbered interfaces that may not support dynamic ARP.

An unnumbered interface has IPv4 capability and is used only in cases where IPv4 is active (IPv4-only and mixed IPv4/IPv6 environments). When configuring an unnumbered interface, the interface specified for the unnumbered interface (system or other) must have an IPv4 address. As well, the interface type for the unnumbered interface will automatically be point-to-point.

The unnumbered option can be used in IES and VPRN access interfaces, as well as in a network interface with MPLS support.

IP subnets

OSPF enables the flexible configuration of IP subnets. Each distributed OSPF route has a destination and mask. A network mask is a 32-bit number that indicates the range of IP addresses residing on a single IP network/subnet. This specification displays network masks as hexadecimal numbers; for example, the network mask for a class C IP network is displayed as 0xffffff00. This mask is often displayed as 255.255.255.0.

Two different subnets with the same IP network number might have different masks, called variable-length subnets. A packet is routed to the longest or most specific match. Host routes are considered to be subnets whose masks are all ones (0xffffffff).

For example, for a packet destined for IP address 10.1.1.1, 10.1.1.0/24 is a longer (better) match than 10.1.1.0/16. If both entries are in the routing table, the route designated by 10.1.1.0/24 will be used.

OSPF instances

A routing instance is a routing entity for a router. The 7705 SAR supports the default routing instance only; it does not support multiple instances. The default routing instance is associated with the global routing table.

Multi-area adjacencies

By default, an IP interface can belong to one OSPF area only. However, there may be situations in which the user wants to configure an interface to belong to more than one area. This configuration allows the corresponding link to be considered an intra-area link in multiple areas and to be preferred over other higher-cost intra-area links.

For example, as shown in the following figure, a high-speed backbone link (in area 0) is established between two ABRs (R1 and R2). The user wants traffic between R1 and R2 in area 1 to use that high-speed link as well. Because intra-area paths are preferred over inter-area paths, by default, R1 will always use the lower-speed links in area 1 to route the traffic. To enable area 1 to use the high-speed link, the user can configure the high-speed interface to belong to both area 0 and area 1.

Figure 4. Multi-area adjacency

The 7705 SAR supports the use of a single IP interface in multiple areas as defined in RFC 5185, OSPF Multi-Area Adjacency. With multi-area adjacency, OSPF routers establish multiple adjacencies for different areas over a single logical interface. Each multi-area adjacency is announced as an unnumbered point-to-point link in the configured area by the routers connected to the link. For each area, one logical interface is treated as the primary interface and the other interfaces configured for the area are designated as secondary interfaces.

A logical interface can be configured as the primary interface for one area only. For any other area for which that interface is configured, the interface must be specified as secondary with the command config>router>ospf (ospf3)>area>interface ip-int-name secondary. It is recommended that area 0 (backbone area) be used for the primary interface association.

Multi-area adjacency is supported for OSPF and OSPFv3. It is also supported under the VPRN context.

OSPF import policies

By default, OSPF imports all the routes advertised via LSAs. Import policies allow routes that match a certain criteria, such as neighbor IP addresses, to be rejected. Users must use caution when applying import policies, since not using certain routes may result in network stability issues.

Import policies are supported within the base router context and the VPRN context. Import policies are not supported on OSPFv3.

Bidirectional forwarding detection (BFD) for OSPF

BFD is a simple protocol for detecting failures in a network. BFD uses a ‟hello” mechanism that sends control messages periodically to the far end and receives periodic control messages from the far end. BFD can detect device, link, and protocol failures.

BFD can be enabled using OSPFv2 (for IPv4) or OSPFv3 (for IPv6). Additionally, a network can be configured to use both OSPFv2 and OSPFv3.

When BFD is enabled on an OSPF interface, the state of the interface is tied to the state of the BFD session between the local node and remote (far-end) node. BFD is implemented in asynchronous mode only, meaning that neither end responds to control messages; rather, the messages are sent in the time period configured at each end.

If the configured number of consecutive BFD missed messages is reached, the link is declared down and OSPF takes the appropriate action (for example, generates an LSA update against the failed link or reroutes around the failed link).

Due to the lightweight nature of BFD, it can detect failures faster than other detection protocols, making it ideal for use in applications such as mobile transport.

Graceful restart helper

Graceful restart and non-stop routing (NSR) both provide mechanisms that allow neighbor routers to handle a service interruption due to a CSM switchover. Data packets continue to be forwarded along known routes while the OSPF information is being restored or refreshed following the switchover.

With graceful restart, a router undergoing a switchover informs its adjacent neighbors and requests a grace period whereby traffic is still forwarded based on the last known good FIB while the router restarts. The neighbor must cooperate with the requesting router in order for the traffic to be forwarded. After the switchover, the neighbor relationships must be re-established.

With NSR (or high-availability service), routing neighbors are unaware of any event on the router performing a switchover. All activity switches to the inactive CSM, which maintains up-to-date routing information, so that routing topology and reachability are not affected. NSR is a more reliable and robust way of handling service interruptions than graceful restart.

The 7705 SAR supports NSR; therefore, graceful restart is not implemented on the router. However, to support neighbor routers that do not have high-availability service, the 7705 SAR supports graceful restart helper. In graceful restart helper mode, the 7705 SAR never requests graceful restart support. However, if a grace LSA is received from an OSPF neighbor, the 7705 SAR keeps the link toward that neighbor up and operational until the specified grace period in the grace LSA expires or the graceful restart is successful, whichever comes first.

LFA protection using segment routing backup node SID

One of the challenges in MPLS deployments across multiple IGP areas or domains, such as in seamless MPLS design, is the provisioning of FRR local protection in access and metro domains that make use of a ring, a square, or a partial mesh topology. In order to implement IP, LDP, or SR FRR in these topologies, the remote LFA feature must be implemented. Remote LFA provides a Segment Routing (SR) tunneled LFA next hop for an IP prefix, an LDP tunnel, or an SR tunnel. For prefixes outside of the area or domain, the access or aggregation router must push four labels: service label, BGP label for the destination PE, LDP/RSVP/SR label to reach the exit ABR/ASBR, and one label for the remote LFA next hop. Small routers deployed in these parts of the network have limited MPLS label stack size support.

The following figure illustrates the label stack required for the primary next-hop and the remote LFA next hop computed by aggregation node AGN2 for the inter-area prefix of a remote PE. For an inter-area BGP labeled unicast route prefix for which ABR1 is the primary exit ABR, AGN2 resolves the prefix to the transport tunnel of ABR1 and therefore, uses the remote LFA next hop of ABR1 for protection. The primary next hop uses two transport labels plus a service label. The remote LFA next hop for ABR1 uses PQ node AGN5 and pushes three transport labels plus a service label.

Seamless MPLS with fast restoration requires up to four labels to be pushed by AGN2, as shown in the figure.

Figure 5. Label stack for remote LFA in ring topology

The objective of LFA protection with a backup node segment ID (SID) is to reduce the label stack pushed by AGN2 for BGP labeled unicast inter-area prefixes. When link AGN2-AGN1 fails, packets are directed away from the failure and forwarded toward ABR2, which acts as the backup for ABR1 (and vice versa when ABR2 is the primary exit ABR for the BGP labeled unicast inter-area prefix). This requires that ABR2 advertise a special label for the loopback of ABR1 that will attract packets normally destined for ABR1. These packets will be forwarded by ABR2 to ABR1 via the inter-ABR link.

As a result, AGN2 will push the label advertised by ABR2 to back up ABR1 on top of the BGP label for the remote PE and the service label. This keeps the label stack the same size for the LFA next hop to be the same size as that of the primary next-hop. It is also the same size as the remote LFA next hop for the local prefix within the ring.

Configuring LFA using backup node SID

LFA using a backup node SID is enabled by configuring a backup node SID at an ABR/ASBR that acts as a backup to the primary exit ABR/ASBR of inter-area/inter-as routes learned as BGP labeled routes.

CLI syntax:
config>router>ospf>segment-routing$
    backup-node-sid ip-prefix/prefix-length index 0..4294967295
    backup-node-sid ip-prefix/prefix-length label 1..4294967295

The user can enter either a label or an index for the backup node SID.

Note: This feature only allows the configuration of a single backup node SID per IGP instance and per ABR/ASBR. In other words, only a pair of ABR/ASBR nodes can back up each other in an IGP domain. Each time the user invokes the above command within the same IGP instance, it overrides any previous configuration of the backup node SID. The same ABR/ASBR can, however, participate in multiple IGP instances and provide backup support within each instance.

Detailed operation of LFA protection using backup node SID

As shown in the following figure, LFA for seamless MPLS supports environments where the boundary routers are either:

  • ABR nodes that connect with IBGP multiple domains, each using a different area of the same IGP instance

  • ASBR nodes that connect domains running different IGP instances and use IBGP within a domain and EBGP to the other domains

Figure 6. Backup ABR node SID

The following steps describe the configuration and behavior of LFA protection using backup node SID:

  1. The user configures node SID 100 in ABR1 for its loopback prefix 1.1.1.1/32. This is the regular node SID. ABR1 advertises the prefix SID sub-TLV for this node SID in the IGP and installs the ILM using a unique label.

  2. Each router receiving the prefix sub-TLV for node SID 100 resolves it as described in Segment routing in shortest path forwarding. Changes to the programming of the backup NHLFE of node SID 100 based on receiving the backup node SID for prefix 1.1.1.1/32 are defined in Duplicate SID handling.

  3. The user configures a backup node SID 200 in ABR2 for the loopback 1.1.1.1/32 of ABR1. The SID value must be different from that assigned by ABR1 for the same prefix. ABR2 installs the ILM, which performs a swap operation from the label of SID 200 to that of SID 100. The ILM must point to a direct link and next hop to reach 1.1.1.1/32 of ABR1 as its primary next hop. The IGP examines all adjacencies established in the same area as that of prefix 1.1.1.1/32 and determines which ones have ABR1 as a direct neighbor and with the best cost. If more than one adjacency has the best cost, the IGP selects the one with the lowest interface index. If there is no adjacency to reach ABR2, the prefix SID for the backup node is flushed and is not resolved. This is to prevent any other non-direct path being used to reach ABR1. As a result, any received traffic on the ILM of SID 200 traffic will be blackholed.

  4. If resolved, ABR2 advertises the prefix SID sub-TLV for this backup node SID 200 and indicates in the SR Algorithm field that a modified SPF algorithm, referred to as ‟Backup-constrained-SPF”, is required to resolve this node SID.

  5. Each router receiving the prefix sub-TLV for the backup node SID 200 performs the following steps.

    The following resolution steps do not require a CLI command to be enabled.

    1. The router determines which router is being backed up. This is achieved by checking the router ID owner of the prefix sub-TLV that was advertised with the same prefix but without the backup flag and which is used as the best route for the prefix. In this case, it should be ABR1. Then the router runs a modified SPF by removing node ABR1 from the topology to resolve the backup node SID 200. The primary next hop should point to the path to ABR2 in the counter clockwise direction of the ring.

      The router will not compute an LFA or a remote LFA for node SID 200 because the main SPF used a modified topology.

    2. The router installs the ILM and primary NHLFE for the backup node SID.

      Only a swap label operation is configured by all routers for the backup node SID. There is no push operation, and no tunnel for the backup node SID is added into the TTM.

    3. The router programs the backup node SID as the LFA backup for the SR tunnel to node SID of 1.1.1.1/32 of ABR1. In other words, each router overrides the remote LFA backup for prefix 1.1.1.1/32, which is normally PQ node AGN5.

    4. If the router is adjacent to ABR1, for example AGN1, it also programs the backup node SID as the LFA backup for the protection of any adjacency SID to ABR1.

  6. When node AGN2 resolves a BGP label route for an inter-area prefix for which the primary ABR exit router is ABR1, it will use the backup node SID of ABR1 as the remote LFA backup instead of the SID to the PQ node (AGN5 in this example) to save on the pushed label stack.

    AGN2 continues to resolve the prefix SID for any remote PE prefix that is summarized into the local area of AGN2 as usual. AGN2 programs a primary next hop and a remote LFA next hop. Remote LFA will use AGN5 as the PQ node and will push two labels, as it would for an intra-area prefix SID. There is no need to use the backup node SID for this prefix SID and force its backup path to go to ABR1. The backup path may exit from ABR2 if the cost from ABR2 to the destination prefix is shorter.

  7. If the user excludes a link from LFA in the IGP instance (config>router>ospf>area>interface>loopfree-alternate-exclude or config>router>isis>interface>loopfree-alternate-exclude), a backup node SID that resolves to that interface will not be used as a remote LFA backup in the same way as regular LFA or PQ remote LFA next-hop behavior.

  8. If the OSPF neighbor of a router is put into overload or if the metric of an OSPF interface to that neighbor is set to LSInfinity (0xFFFF), a backup node SID that resolves to that neighbor will not be used as a remote LFA backup in the same way as regular LFA or PQ remote LFA next hop behavior.

  9. If the IS-IS neighbor of a router is put into overload or if the metric of an IS-IS interface to that neighbor is set to overload max-metric (0xfffffe), a backup node SID that resolves to that neighbor will be used as a remote LFA backup in the same way as regular LFA or PQ remote LFA next hop behavior.

    Note: Other routers in the network will not forward transit traffic to the router in overload.

  10. If the IS-IS interface to a neighbor is set to maximum link metric (0xffffff), a backup node SID that resolves to that neighbor will not be used as a remote LFA backup in the same way as regular LFA or PQ remote LFA next hop behavior.

  11. LFA policy is supported for IP next hops only. It is not supported with tunnel next hops such as IGP shortcuts or remote LFA tunnels. A backup node SID is also a tunnel next hop and therefore a user-configured LFA policy will not be applied to check constraints such as admin-groups and SRLG against the outgoing interface of the selected backup node SID.

Duplicate SID handling

When the IGP issues or receives an LSA/LSP containing a prefix SID sub-TLV for a node SID or a backup node SID with a SID value that is a duplicate of an existing SID or backup node SID, the resolution in the following table is followed.

Table 2. Handling of duplicate SIDs 

Old LSA/LSP

New LSA/LSP

Backup node SID

Local backup node SID

Node SID

Local node SID

Backup Node SID

Old

New

New

New

Local Backup Node SID

Old

Equal

New

New

Node SID

Old

Old

Equal/Old1

Equal/New2

Local Node SID

Old

Old

Equal/Old1

Equal/Old1

Notes:

  1. Equal/Old means the following:

    • If the prefix is duplicate, it is equal and no change is needed. Keep the old LSA/LSP.

    • If the prefix is not duplicate, still keep the old LSA/LSP.

  2. Equal/New means the following:

    • If the prefix is duplicate, it is equal and no change is needed. Keep the old LSA/LSP.

    • If the prefix is not duplicate, pick a new prefix and use the new LSA/LSP.

OSPF control plane extensions

All routers supporting OSPF control plane extensions must advertise support of the new algorithm ‟Backup-constrained-SPF” of value 2 in the SR-Algorithm TLV, which is advertised in the Router Information Opaque LSA. This is in addition to the default supported algorithm ‟IGP-metric-based-SPF” of value 0. The following shows the encoding of the prefix SID sub-TLV to indicate a node SID of type backup and to indicate the modified SPF algorithm in the SR Algorithm field. The values used in the Flags field and in the Algorithm field are SR OS proprietary.

The new Algorithm (0x2) field and values are used by this feature.

0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Type             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flags     |   Reserved    |      MT-ID    |Algorithm (0x2)|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     SID/Index/Label (variable)                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The following table lists OSPF control plane extension field values.

Table 3. OSPF control plane extension fields 

Field

Value

Type

2

Length

variable

Flags

1 octet field

The following flags are defined; the ‟B” flag is new:

     0  1  2  3  4  5  6  7
   +--+--+--+--+--+--+--+--+
   |  |NP|M |E |V |L | B|  |
   +--+--+--+--+--+--+--+--+

The following table lists OSPF control plane extension flag values.

Table 4. OSPF control plane extension flags 

Flag

Description

NP-Flag

No-PHP flag

If set, the penultimate hop must not pop the prefix SID before delivering the packet to the node that advertised the prefix SID

M-Flag

Mapping Server Flag

If set, the SID is advertised from the Segment Routing Mapping Server functionality as described in I-D.filsfils-spring-segment-routing-ldp-interop

E-Flag

Explicit-Null Flag

If set, any upstream neighbor of the prefix SID originator must replace the prefix SID with a prefix SID having an Explicit-NULL value (0 for IPv4) before forwarding the packet.

V-Flag

Value/Index Flag

If set, the prefix SID carries an absolute value. If not set, the prefix SID carries an index.

L-Flag

Local/Global Flag

If set, the value/index carried by the prefix SID has local significance. If not set, the value/index carried by this sub-TLV has global significance.

B-Flag

This flag is used by the Protection using backup node SID feature. If set, the SID is a backup SID for the prefix. This value is SR OS proprietary.

Other bits

Reserved

These must be zero when sent and are ignored when received.

MT-ID

Multi-Topology ID, as defined in RFC 4915

Algorithm

One octet identifying the algorithm the prefix SID is associated with. A value of (0x2) indicates the modified SPF algorithm, which removes from the topology the node that is backed up by the backup node SID. This value is SR OS proprietary.

SID/Index/Label

Based on the V and L flags, it contains either:

  • a 32-bit index defining the offset in the SID/Label space advertised by this router

  • a 24-bit label where the 20 rightmost bits are used for encoding the label value

Topology-independent LFA for OSPF

OSPFv2 supports topology-independent LFA (TI-LFA), which improves the protection coverage of a network topology by computing and automatically instantiating a repair tunnel to a Q node that is not in the shortest path from the computing node. The 7705 SAR supports TI-LFA for both link protection and node protection. See Topology-independent LFA and Node protection support in remote LFA and TI-LFA for more information. The information in these sections refers to IS-IS but also applies to OSPF.

LDP and IP fast reroute (FRR) for OSPF prefixes

LDP fast reroute (FRR) provides local protection for an LDP FEC by precalculating and downloading a primary and a backup NHLFE for the FEC to the LDP FIB. The primary NHLFE corresponds to the label of the FEC received from the primary next hop as per the standard LDP resolution of the FEC prefix in the RTM. The backup NHLFE corresponds to the label received for the same FEC from a loop-free alternate (LFA) next hop.

LDP FRR improves convergence in case of a local link or node failure in the network, by using the label-FEC binding received from the LFA next hop to forward traffic for a given prefix as soon as the primary next hop is not available. This means that a router resumes forwarding LDP packets to a destination prefix using the backup path without waiting for the routing convergence.

IP fast reroute (FRR) protects against link or node failures in an IP network by precalculating a backup route to use when the primary next hop is not available. Both routes are populated in the RTM. IP FRR uses an LFA backup next hop to forward in-transit IP packets as soon as the primary next hop failure is detected and the backup is invoked. This means that a node resumes forwarding IP packets to a destination prefix without waiting for the routing convergence.

See RFC 5286, Basic Specification for IP Fast Reroute: Loop-Free Alternates, for more information about LFAs.

See the 7705 SAR MPLS Guide ‟LDP Fast Reroute (FRR)” for more information about LDP FRR and the 7705 SAR Router Configuration Guide, ‟IP Fast Reroute (FRR)” for more information about IP FRR.

LFAs are supported on IPv4 and IPv6 OSPF prefixes, VPN IPv4 OSPF prefixes, and on inter-area OSPF prefixes. LFAs are also supported on IPv4 IS-IS prefixes and on inter-level IS-IS prefixes. For information about LFA support for IS-IS prefixes, see LDP and IP fast reroute (FRR) for IS-IS prefixes.

IP FRR also provides an LFA backup next hop for the destination prefix of a GRE tunnel used in an SDP or in VPRN autobind.

LFA calculations

In addition to performing the shortest path first (SPF) calculation of the primary next hop, OSPF must calculate a backup next hop for all prefixes used by LDP to resolve FECs and for all prefixes used by IP to forward packets. The backup next hops are calculated to provide single link or node protection and to guarantee that when a failure occurs, forwarding traffic through the backup next hop will not result in a loop. These backup next hops are called Loop-Free Alternates (LFAs).

The 7705 SAR supports remote LFA for both link protection and node protection. For detailed information about the remote LFA algorithm, see Remote LFA with segment routing.

In general, in order to calculate LFAs for a specific destination (D), a router must know the following information:

  • the shortest-path distance from the calculating router (source) to the destination (SP(S,D))

  • the shortest-path distance from the router’s OSPF neighbors to the destination (SP(N,D))

  • the shortest-path distance from the router’s OSPF neighbors to itself (SP(N,S))

A neighbor (N) can provide an LFA only if:

SP(N,D) < SP(N,S) + SP(S,D)

This is known as loop-free criterion.

The following figure shows an example of a backup route resulting in a microloop. In the example, PE-1 uses PE-2 as its next hop to reach PE-3. The total cost to reach PE-3 via PE-2 is 9. If the link between PE-1 and PE-2 fails, PE-1 can try to use PE-4 as its next hop to reach PE-3. However, the metric between PE-4 and PE-3 is 30. From the perspective of PE-4, forwarding traffic via the PE-1 and PE-2 path to PE-3 is more viable, as the cost is 17 (8 + 5 + 4) versus the direct link cost of 30. Therefore, if PE-1 forwards the traffic to PE-4 in order to reach PE-3, PE-4 forwards it back to PE-1, creating a microloop, until the routing protocols converge and declare the link between PE-1 and PE-2 to be down. PE-4 would then be forced to take the direct PE-3 link to reach PE-3 as there is no other alternative. Because PE-4 does not meet the loop-free criterion, it cannot be used as a valid LFA.

Figure 7. Backup routes resulting in microloops

The following figure shows an example of an LFA backup route. In this example, PE-1 again uses PE-2 as its next hop to reach PE-3. The total cost to reach PE-3 via PE-2 is 9. If the link between PE-1 and PE-2 fails, PE-1 can use PE-4 to reach PE-3. From the perspective of PE-4, the direct route to PE-3 is a viable route, as the cost is 3 versus the cost of forwarding traffic via PE-1 (17). Using the direct route does not cause microloops and meets the loop-free criterion; therefore, PE-4 can be used as a valid LFA.

Figure 8. LFA backup route

Selection algorithm

For a point-to-point interface, if SPF finds multiple LFA next hops for a given primary next hop, the selection algorithm is as follows:

  1. SPF will pick the node-protect type over the link-protect type.

  2. If there is more than one LFA next hop within the selected type, it will pick one based on the least cost.

  3. If there is more than one LFA next hop with the same cost, SPF will select the first one. This is not a deterministic selection and will vary for each SPF calculation.

For a broadcast interface, a node-protect LFA is not necessarily a link-protect LFA if the path to the LFA next hop goes over the same pseudonode as the primary next hop. Similarly, a link-protect LFA may not guarantee link protection if it goes over the same pseudonode as the primary next hop.

When SPF finds multiple LFA next hops for a given primary next hop, the selection algorithm is as follows:

  1. The algorithm splits the LFA next hops into two sets:

    • the first set consists of LFA next hops that do not go over the pseudonode used by the primary next hop

    • the second set consists of LFA next hops that do go over the pseudonode used by the primary next hop

  2. If there is more than one LFA next hop in the first set, it will pick the node-protect type over the link-protect type.

  3. If there is more than one LFA next hop within the selected type, it will pick one based on the least cost.

  4. If there is more than one LFA next hop with the same cost, SPF will select the first one from the remaining set. This is not a deterministic selection and will vary for each SPF calculation.

  5. If no LFA next hop results from step 4, SPF will rerun steps 2 to 4 using the second set.

Note: A node-protect LFA that does not guarantee link protection can still be selected as a last resort; as well, a link-protect LFA that does not guarantee node protection can still be selected as a last resort.

Both the calculated primary next hop and LFA next hop for a given prefix are programmed into the RTM.

LFA configuration

To enable LFA for OSPF prefixes, use the following command:

  config>router>ospf>loopfree-alternates

or

 config>router>ospf3>loopfree-alternates

Next, enable FRR for LDP and/or IP by entering the following commands:

  config>router>ldp>fast-reroute

  config>router>ip-fast-reroute

These commands instruct the OSPF SPF algorithm to precalculate a primary next hop and LFA next hop for every learned prefix, in order to provide FRR to LDP FEC packets and/or IP packets.

To exclude all interfaces within a specific OSPF area or to exclude a specific IP interface from being included in the LFA SPF calculation, enter the following commands:

 config>router>ospf>area>loopfree-alternate-exclude

or

  config>router>ospf3>area>loopfree-alternate-exclude

  config>router>ospf>area>interface>loopfree-alternate-exclude

or

  config>router>ospf3>area>interface>loopfree-alternate-exclude

If IGP shortcuts are also enabled, any LSPs with a destination address in that OSPF area are not included in the LFA SPF calculation.

If an interface is excluded from the LFA SPF, it is excluded in all areas. However, the loopfree-alternate-exclude command can only be executed under the area in which the specified interface is primary. When the command is executed, the interface is excluded in that area and in all other areas where the interface is secondary. If the user attempts to execute the command under an area where the interface is secondary, the command will fail.

Note: The loopfree-alternates and loopfree-alternate-exclude commands are also supported for OSPF and OSPFv3 within a VPRN service.

IGP shortcuts (RSVP-TE tunnels)

Microloops, especially in ring topologies, are typically unavoidable. As the number of nodes in a ring increases, the chance of microloops occurring also increases. In cases where a valid directly connected next hop cannot be ensured, remote LFAs can be used. Remote LFAs are non-directly connected LFA next hops that are reached via IGP shortcuts.

IGP shortcuts are an MPLS functionality where LSPs are treated like physical links within IGPs; that is, LSPs can be used for next hop reachability. If an RSVP-TE LSP is used as a shortcut by OSPF or IS-IS, it is included in the SPF calculation as a point-to-point link for both primary and LFA next hops. It can also be advertised to neighbors so that the neighboring nodes can also use the links to reach a destination via the advertised next hop.

IGP shortcuts can be used to simplify remote LFA support and simplify the number of LSPs required in a ring topology.

IGP shortcut functionality provides two options:

  • LFA-protect option

    This option allows an LSP to be included in both the main SPF and the loop-free alternate (LFA) SPF algorithm. For a specific prefix, the LSP can be used either as a primary next hop or as an LFA next hop, but not both.

    If the main SPF calculation selects a tunneled primary next hop for a prefix, the LFA SPF calculation will not select an LFA next hop for this prefix and the protection of this prefix will rely on the RSVP LSP FRR protection.

    If the main SPF calculation selects a direct primary next hop, the LFA SPF calculation will select an LFA next hop for this prefix but will prefer a direct LFA next hop over a tunneled LFA next hop.

  • LFA-only option

    This option allows an LSP to be included in the LFA SPF algorithm only, which means that the introduction of IGP shortcuts does not affect the main SPF decision. For a specific prefix, the main SPF calculation always selects a direct primary next hop. The LFA SPF calculation will select an LFA next hop for this prefix but will prefer a direct LFA next hop over a tunneled LFA next hop.

Selection algorithm

If there are multiple LFA next hops for a primary next hop, the selection algorithm is as follows:

  1. The algorithm splits the LFA next hops into two sets:

    • the first set consists of direct LFA next hops

    • the second set consists of tunneled LFA next hops after excluding the LSPs that use the same outgoing interface as the primary next hop

  2. The algorithm continues with the first set if it is not empty; otherwise, it continues with the second set.

  3. If the second set is used, the algorithm selects the tunneled LFA next hop whose endpoint corresponds to the node advertising the prefix:

    • if more than one tunneled next hop exists, it selects the one with the lowest LSP metric

    • if more than one tunneled next hop still exists, it selects the one with the lowest tunnel ID

    • if none is available, it continues with rest of the tunneled LFAs in the second set

  4. Within the selected set, the algorithm splits the LFA next hops into two sets:

    • the first set consists of LFA next hops that do not go over the pseudonode used by the primary next hop

    • the second set consists of LFA next hops that go over the pseudonode used by the primary next hop

  5. If there is more than one LFA next hop in the selected set, it will pick the node-protect type over the link-protect type.

  6. If there is more than one LFA next hop within the selected type, it will pick one based on the least total cost for the prefix. For a tunneled next hop, that means the LSP metric plus the cost of the LSP endpoint to the destination of the prefix.

  7. If there is more than one LFA next hop within the selected type in the first set (ECMP is configured), it will select the first direct next hop from the remaining set. This is not a deterministic selection and will vary for each SPF calculation.

  8. If there is more than one LFA next hop within the selected type in the second set (ECMP is configured), it will pick the tunneled next hop with the lowest cost from the endpoint of the LSP to the destination prefix. If there remains more than one next hop, it will pick the tunneled next hop with the lowest tunnel ID.

Forwarding adjacency

The forwarding adjacency feature allows OSPF to advertise an RSVP-TE LSP as a link so that other routers in the network can include it in the SPF calculations. The RSVP-TE is advertised as an unnumbered point-to-point link and the link-state advertisement (LSA) has no traffic engineering opaque sub-TLVs as per RFC 3906, Calculating Interior Gateway Protocol (IGP) Routes Over Traffic Engineering Tunnels.

The forwarding adjacency feature can be enabled independently from the IGP shortcut feature. If both features are enabled for OSPF, forwarding adjacency takes precedence.

When forwarding adjacency is enabled, each node advertises a point-to-point unnumbered link for each best-metric tunnel to the router ID of any endpoint node. The node does not include the tunnels as IGP shortcuts in the SPF calculation directly. Instead, when the LSA advertising the corresponding point-to-point unnumbered link is installed in the local routing database, the node performs an SPF calculation using the link like any other link LSA. The link bidirectional check requires that a regular link or tunnel link exist in the reverse direction for the tunnel to be used in SPF calculations.

IGP shortcut configuration

To enable the use of IGP shortcuts by OSPF, enter the following command:

  config>router>ospf>rsvp-shortcut

To enable forwarding adjacency in OSPF, enter the following command:

  config>router>ospf>advertise-tunnel-link

To enable the use of an RSVP-TE LSP by OSPF as a shortcut or as a forwarding adjacency for resolving IGP routes, enter the following command:

  config>router>mpls>lsp>igp-shortcut

When the rsvp-shortcut or advertise-tunnel-link option is enabled in OSPF, all RSVP-TE LSPs originating on this node are eligible by default as long as the destination address of the LSP, as configured with the config>router> mpls>lsp>to command, corresponds to a router ID of a remote node. A specific LSP can be excluded from being used as a shortcut or forwarding adjacency with the no form of the igp-shortcut command.

LFA SPF policies

An LFA SPF policy allows the user to apply specific criteria to the selection of a LFA backup next hop for a subset of prefixes that resolve to a specific primary next hop. The 7705 SAR supports the following LFA SPF policy constraints:

  • admin group

  • shared risk link group (SRLG)

  • protection type

  • next hop type

A route next hop policy template must first be created under the global router context. The template contains criteria for the policies in the preceding list.

The template is then applied to prefixes protected by LFA. Each instance of OSPF can apply the same policy template to one or more prefixes and interfaces. If a template is modified, OSPF re-evaluates it for any changes and, if necessary, schedules a new LFA SPF to recalculate the LFA next hop for any prefixes associated with the template.

As a related feature, prefixes that match a prefix entry in a prefix policy can be excluded from the LFA SPF calculation. If a prefix is excluded, it is not included in the LFA SPF calculation, regardless of its priority. Prefix policies are created with the config>router>policy-options>prefix-list command (for information about prefix lists, see the 7705 SAR Router Configuration Guide, ‟Route Policies”.

LFA SPF policy configuration

To create a route next hop policy template, enter the following command:

  config>router>route-next-hop-policy template

Configure the template with policy constraints for the items in the preceding list.

Note: To configure constraints for admin groups and SRLG groups, these groups must already be created in the config>router>if-attribute>admin-group and config>router>if-attribute>srlg-group contexts.

Next, apply the template to OSPF interfaces by entering the following command:

  config>router>ospf>area>interface>lfa-policy-map>route-nh-template

or

  config>router>ospf3>area>interface>lfa-policy-map>route-nh-template

The template is applied to all prefixes using the specified interface name.

When a route next hop policy template is applied to an interface, it is applied in all areas. However, the route-nh-template command can only be executed under the area in which the specified interface is primary. When the command is executed, the template is applied in that area and in all other areas where the interface is secondary. If the user attempts to execute the command under an area where the interface is secondary, the command will fail.

Optionally, exclude prefixes in a prefix policy from the LFA SPF calculation by entering the following command:

  config>router>ospf>loopfree-alternates>exclude>prefix-policy

or

  config>router>ospf3>loopfree-alternates>exclude>prefix-policy

Note: The lfa-policy-map and loopfree-alternate-exclude commands are also supported for OSPF within a VPRN service.

Preconfiguration requirements

The router ID must be available before OSPF can be configured. The router ID is a 32-bit IP address assigned to each router running OSPF. This number uniquely identifies the router within an AS. OSPF routers use the router IDs of the neighbor routers to establish adjacencies. Neighbor IDs are learned when Hello packets are received from the neighbor.

Before configuring OSPF parameters, ensure that the router ID is derived by one of the following methods:

  • define the value using the config>router>router-id ip-address command

  • define the system interface using the config>router>interface ip-int-name command (used if the router ID is not specified with the config>router>router-id ip-address command)

    A system interface must have an IP address with a 32-bit subnet mask. The system interface is assigned during the primary router configuration process when the interface is created in the logical IP interface context.

  • if you do not specify a router ID, the last 4 bytes of the MAC address are used

OSPF configuration process overview

The following figure displays the process to provision basic OSPF parameters.

Figure 9. OSPF configuration process

Configuration notes

  • Before OSPF can be configured, the router ID must be configured.

  • The basic OSPF configuration includes at least one area and an associated interface.

  • All default and command parameters can be modified.

  • By default, a router has no configured areas.

  • The base OSPF instance is created in the administratively enabled state.

OSPF configuration guidelines

Configuration planning is essential to organize routers, backbone, non-backbone, stub, NSSA areas, and transit links. OSPF provides essential defaults for basic protocol operability. You can configure or modify most commands and parameters.

The minimal OSPF parameters that are necessary to deploy OSPF are:

  • router ID

    Each router running OSPF must be configured with a unique router ID. The router ID is used by the OSPF routing protocol to establish adjacencies.

    If a new router ID is defined, the OSPF protocol is not automatically restarted with the new ID. The router must be shut down and restarted in order to initialize the new router ID.

  • area

    At least one OSPF area must be created. An interface must be assigned to each OSPF area.

  • interfaces

    An interface is the connection between a router and one of its attached networks. An interface has state information associated with it, which is obtained from the underlying lower-level protocols and the routing protocol. An interface to a network has associated with it a single IP address and mask (unless the network is an unnumbered point-to-point network). An interface is sometimes also referred to as a link.

All configuration applies to both OSPF and OSPFv3 unless specifically noted in the OSPF command reference.

Basic OSPF configuration

This section provides information to configure OSPF as well as configuration examples of common configuration tasks.

The minimal OSPF parameters that need to be configured are:

  • a router ID

  • one or more areas

  • interfaces (interface ‟system”)

The following is an example of a basic OSPF configuration:

ALU-A>config>router>ospf# info
----------------------------------------------
            area 0.0.0.0
                interface "system"
                exit
            exit
            area 0.0.0.20
                nssa
                exit
                interface "to-104"
                    priority 10
                exit
            exit
            area 0.0.1.1
            exit
----------------------------------------------
ALU-A>config>router>ospf#

Configuring the router ID

The router ID uniquely identifies the router within an AS. In OSPF, routing information is exchanged between autonomous systems, which are groups of networks that share routing information. The router ID can be set to be the same as the system interface address (loopback address). This is the default setting.

The router ID is derived by one of the following methods:

  • defining the value using the config>router>router-id ip-address command

  • defining the system interface using the config>router>interface ip-int-name command (used if the router ID is not specified with the config>router>router-id ip-address command)

  • inheriting the last 4 bytes of the MAC address

When configuring a new router ID, protocols are not automatically restarted with the new router ID. The next time a protocol is initialized, the new router ID is used. To force the new router ID, issue the shutdown and no shutdown commands for OSPF or restart the entire router.

Use the following CLI syntax to configure a router ID (in the config>router context):

CLI syntax:
router-id ip-address

The following displays a router ID configuration example:

A:ALU-B>config>router# info
#------------------------------------------
# IP Configuration
#------------------------------------------
        interface "system"
            address 10.10.10.104/8
        exit
        interface "to-103"
            address 10.0.0.104/8
            port 1/1/1
        exit
        router-id 10.10.10.104
...
#------------------------------------------
A:ALU-B>config>router# 

Configuring an OSPF area

An OSPF area consists of routers configured with the same area ID. To include a router in a specific area, the common area ID must be assigned and an interface identified.

If your network consists of multiple areas, you must also configure a backbone area (0.0.0.0) on at least one router. The backbone contains the area border routers and other routers not included in other areas. The backbone distributes routing information between areas. To maintain backbone connectivity, there must be at least one interface in the backbone area or a virtual link must be configured to another router in the backbone area.

The minimal configuration must include an area ID and an interface. Modifying other command parameters is optional.

Use the following CLI syntax to configure an OSPF area (in the config>router context):

CLI syntax:
area area-id
    area-range ip-prefix/mask [advertise | not-advertise]
    blackhole-aggregate

The following displays an OSPF area configuration example:

A:ALU-A>config>router>ospf# info
----------------------------------------------
            area 0.0.0.0
            exit
            area 0.0.0.20
            exit
----------------------------------------------
ALU-A>config>router>ospf#

Configuring an interface

In OSPF, an interface can be configured to act as a connection between a router and one of its attached networks. An interface includes state information that was obtained from underlying lower-level protocols and from the routing protocol itself. An interface to a network is associated with a single IP address and mask (unless the network is an unnumbered point-to-point network). If the address is removed from an interface, all OSPF data for the interface is also removed. If the address is merely changed, the OSPF configuration is preserved.

The passive command enables the passive property to and from the OSPF interface where passive interfaces are advertised as OSPF interfaces but do not run the OSPF protocol. By default, only interface addresses that are configured for OSPF are advertised as OSPF interfaces. The passive parameter allows an interface to be advertised as an OSPF interface without running the OSPF protocol. When enabled, the interface will ignore ingress OSPF protocol packets and not transmit any OSPF protocol packets.

An interface can be associated with more than one area, as specified in RFC 5185. To enable an interface to be associated with multiple areas, include the secondary keyword when creating the interface.

Use the following CLI syntax to configure an OSPF interface in the config>router context:

CLI syntax:
ospf 
    area area-id
        interface ip-int-name [secondary]
            advertise-subnet
            auth-keychain name
            authentication-key {authentication-key|hash-key} [hash|hash2]
            authentication-type [password | message-digest]
            bfd-enable [remain-down-on-failure]
            dead-interval seconds
            hello-interval seconds
            interface-type {broadcast|point-to-point}
            message-digest-key key-id md5 [key|hash-key] [hash|hash2]
            metric metric
            mtu bytes
            passive
            priority number
            retransmit-interval seconds
            no shutdown
            transit-delay seconds

The following displays an interface configuration example:

A:ALU-49>config>router>ospf# info
----------------------------------------------
            asbr
            overload
            overload-on-boot timeout 60
            traffic-engineering
            export "OSPF-Export"
            exit
            area 0.0.0.0
                virtual-link 10.2.3.4 transit-area 1.2.3.4
                    hello-interval 9
                    dead-interval 40
                exit
                interface "system"
                exit
            exit
            area 0.0.0.20
                interface "to-103" secondary
                exit
            exit
            area 0.0.0.25
                nssa
                exit
            exit
            area 1.2.3.4
            exit
----------------------------------------------
A:ALU-49>config>router>ospf#

Configuring other OSPF components

The following sections show the CLI syntax for:

Configuring a stub area

Configure stub areas to control external advertisement flooding and to minimize the size of the topological databases on an area’s routers. A stub area cannot also be configured as an NSSA. The area ID cannot be 0.0.0.0 – this address is reserved for the backbone area.

By default, summary route advertisements (type 3 LSAs) are sent into stub areas. The no form of the summary command disables sending summary route advertisements, and only the default route is advertised by the ABR.

Stub areas cannot be used as transit areas. If the area was originally configured as a transit area for a virtual link, existing virtual links are removed when its designation is changed to NSSA or stub.

Use the following CLI syntax to configure a stub area:

CLI syntax:
ospf
    area area-id
        stub
            default-metric metric
            summaries

The following displays a stub configuration example:

ALU-A>config>router>ospf>area># info
----------------------------------------------
...
            area 0.0.0.0
            exit
            area 0.0.0.20
                stub
                exit
            exit

Configuring a not-so-stubby area

NSSAs are similar to stub areas in that no external routes are imported into the area from other OSPF areas. The major difference between a stub area and an NSSA is that an NSSA can flood external routes that it learns throughout its area and from an area border router to the entire OSPF domain. An area cannot be both a stub area and an NSSA. The area ID cannot be 0.0.0.0 – this address is reserved for the backbone area.

NSSAs cannot be used as transit areas. If the area was originally configured as a transit area for a virtual link, existing virtual links are removed when its designation is changed to NSSA or stub.

Use the following CLI syntax to configure NSSAs:

CLI syntax:
ospf 
    area area-id
        nssa
            area-range ip-prefix/mask [advertise | not-advertise]
            originate-default-route [type-7][no-adjacency-check]
            redistribute-external
            summaries

The following displays an NSSA configuration example:

A:ALU-49>config>router>ospf# info
----------------------------------------------          
...
            area 0.0.0.25
                nssa
                exit
            exit
----------------------------------------------
A:ALU-49>config>router>ospf#

Configuring a virtual link

The backbone area (area 0.0.0.0) must be contiguous and all other areas must be connected to the backbone area. If it is not possible or practical to connect an area to the backbone, the area border routers must be connected via a virtual link. Two area border routers will form a point-to-point-like adjacency across the transit area. A virtual link can only be configured while in the context of area 0.0.0.0. The transit area cannot be a stub area or an NSSA.

The router-id parameter specified in the virtual-link command must be associated with the virtual neighbor; that is, the router ID of the far-end router must be specified, not the local router ID.

Use the following CLI syntax to configure a virtual link:

CLI syntax:
ospf
    area area-id
        virtual-link router-id transit-area area-id
            auth-keychain name
            authentication-key {authentication-key | hash-key} [hash | hash2] 
            authentication-type [password | message-digest]
            dead-interval seconds
            hello-interval seconds
            message-digest-key key-id md5 [key | hash-key] [hash | hash2]
            retransmit-interval seconds
            transit-delay
            no shutdown

The following displays a virtual link configuration example:

A:ALU-49>config>router>ospf# info
----------------------------------------------
...
            area 0.0.0.0
                virtual-link 10.2.3.4 transit-area 1.2.3.4
                    hello-interval 9
                    dead-interval 40
                exit
            exit
            area 0.0.0.20
                stub
                exit
            exit
            area 0.0.0.25
                nssa
                exit
            exit
            area 1.2.3.4
            exit

Configuring authentication

Authentication must be explicitly configured and can be done using two separate mechanisms:

  • configuration of an explicit authentication key and algorithm using the authentication-key and authentication-type commands at the interface level or the virtual link level

  • configuration of an authentication keychain using the auth-keychain command in the config>system>security>keychain context and associating the keychain with the interface or virtual link

Either the authentication-key command or the auth-keychain command can be used by OSPF, but both cannot be supported at the same time. If both commands are configured, the auth-keychain configuration will be applied and the authentication-key command will be ignored.

Use the following CLI syntax to configure authentication:

CLI syntax:
ospf 
    area area-id
        interface ip-int-name
            authentication-key {authentication-key | hash-key} [hash | hash2]
            authentication-type [password | message-digest]
            message-digest-key key-id md5 [key | hash-key] [hash | hash2]
        virtual-link router-id transit-area area-id
            authentication-key {authentication-key | hash-key} [hash|hash2]
            authentication-type [password | message-digest]
            message-digest-key key-id md5 [key | hash-key] [hash | hash2]

The following displays authentication configuration examples:

A:ALU-49>config>router>ospf# info
----------------------------------------------
...
            
            area 0.0.0.40
                interface "test1"
                    authentication-type password
                    authentication-key "3WErEDozxyQ" hash
                exit
            exit
            area 1.2.3.4
            exit
----------------------------------------------
A:ALU-49>config>router>ospf#


A:ALU-49>config>router>ospf# info
----------------------------------------------
...
            
            area 0.0.0.0
                virtual-link 10.0.0.1 transit-area 0.0.0.1
                    authentication-type message-digest
                    message-digest-key 2 md5 "Mi6BQAFi3MI" hash
                exit
                virtual-link 10.2.3.4 transit-area 1.2.3.4
                    hello-interval 9
                    dead-interval 40
                exit
                interface "system"
                exit
            exit
----------------------------------------------
A:ALU-49>config>router>ospf#

Use the following CLI syntax to associate an interface or virtual link with an authentication keychain. The keychain must already be defined in the system>security>keychain context.

CLI syntax:
ospf 
    area area-id
        interface ip-int-name
            auth-keychain name
        virtual-link router-id transit-area area-id
            auth-keychain name

Assigning a designated router

The designated router is responsible for flooding network link advertisements on a broadcast network to describe the routers attached to the network. A router uses Hello packets to advertise its priority. The router with the highest-priority interface becomes the designated router. If routers have the same priority, the designated router is elected based on the highest router ID. A router with priority 0 is not eligible to be a designated router or a backup designated router. At least one router on each logical IP network or subnet must be eligible to be the designated router. By default, routers have a priority value of 1.

When a router starts up, it checks for a current designated router. If a designated router is present, the router accepts that designated router, regardless of its own priority designation. If the designated and backup designated routers fail, new designated and backup routers are elected according to their priority numbers or router IDs (in case of a priority tie).

Designated routers are used only in multi-access (broadcast) networks.

Use the following CLI syntax to configure the designated router:

CLI syntax:
ospf 
    area area-id
        interface ip-int-name
            priority number

The following displays a priority designation example:

A:ALU-49>config>router>ospf# info
----------------------------------------------
...
            
            area 0.0.0.25
                nssa
                exit
                interface "if2"
                    priority 100
                exit
            exit
----------------------------------------------
A:ALU-49>config>router>ospf#

Configuring route summaries

ABRs send summary advertisements (type 3 LSAs) into a stub area or NSSA to describe the routes to other areas. This command is particularly useful in order to reduce the size of the link-state database within the stub or NSSA.

By default, summary route advertisements are sent into the stub area or NSSA. The no form of the summaries command disables sending summary route advertisements and, in stub areas, the default route is advertised by the area border router.

Use the following CLI syntax to configure a route summary:

CLI syntax:
ospf
    area area-id
        stub
            summaries
        nssa
            summaries

The following displays a stub route summary configuration example:

A:ALU-49>config>router>ospf# info
----------------------------------------------
...
            area 0.0.0.20
                stub
                    summaries
                exit
                interface "to-103"
                exit
            exit
----------------------------------------------
A:ALU-49>config>router>ospf# 

Configuring route preferences

A router can learn routes from different protocols and distribute them into OSPF, in which case, the costs are not comparable. When this occurs, the preference value is used to decide which route is installed in the forwarding table and used as the path to the destination. The route with the lowest preference value is selected.

The 7705 SAR supports the redistribution of static routes and routes from directly attached and aggregated networks into OSPF.

Different protocols should not be configured with the same preference. If this occurs, the tiebreaker is based on the default preferences as defined in Route preference defaults by route type.

If multiple routes are learned with an identical preference using the same protocol, the lowest-cost route is used. If multiple routes are learned with an identical preference using the same protocol and the costs (metrics) are equal, the decision of what route to use is determined by the configuration of ECMP in the config>router context. See the 7705 SAR Router Configuration Guide for information about ECMP.

Table 5. Route preference defaults by route type

Route type

Preference

Configurable

Direct attached

0

No

Static routes

5

Yes

OSPF internal

10

Yes

IS-IS level 1 internal

15

Yes

IS-IS level 2 internal

18

Yes

OSPF external

150

Yes

IS-IS level 1 external

160

Yes

IS-IS level 2 external

165

Yes
Note: To configure a preference for static routes, use the config>router>static-route-entry context. See the 7705 SAR Router Configuration Guide, ‟IP Router Command Reference”, for information.

Use the following CLI syntax to configure a route preference for OSPF internal and external routes:

CLI syntax:
ospf
    preference preference
    external-preference preference

The following displays a route preference configuration example:

A:ALU-49>config>router>ospf# info
----------------------------------------------
            asbr
            overload
            overload-on-boot timeout 60
            traffic-engineering
            preference 9
            external-preference 140
            exit
----------------------------------------------
A:ALU-49>config>router>ospf#

OSPF configuration management tasks

This section discusses the following OSPF configuration management tasks:

Modifying a router ID

Because the router ID is defined in the config>router context, not in the OSPF configuration context, the protocol instance is not aware of changes to the ID value. Changing the router ID on a device could cause configuration inconsistencies if associated values are not also modified.

After you have changed a router ID, manually shut down and restart the protocol using the shutdown and no shutdown commands in order for the changes to be incorporated.

Use the following CLI syntax to change a router ID number:

CLI syntax:
config>router# router-id ip-address

The following displays an NSSA router ID modification example:

A:ALU-49>config>router# info
------------------------------------------
IP Configuration
------------------------------------------
        interface "system"
            address 10.10.10.104/8
        exit
        interface "to-103"
            address 10.0.0.103/8
            port 1/1/1
        exit
        router-id 10.10.10.104
------------------------------------------
A:ALU-49>config>router#

Deleting a router ID

You can modify a router ID, but you cannot delete the parameter. If the no router router-id command is issued, the router ID reverts to the default value, the system interface address (which is also the loopback address). If a system interface address is not configured, the last 4 bytes of the chassis MAC address are used as the router ID.

Modifying OSPF parameters

You can change or remove existing OSPF parameters in the CLI. The changes are applied immediately.

The following example displays an OSPF modification in which an interface is removed and another interface added.

Example:
config>router# ospf 
config>router>ospf# area 0.0.0.20
config>router>ospf>area# no interface "to-103"
config>router>ospf>area# interface "to-HQ"
config>router>ospf>area>if$ priority 50
config>router>ospf>area>if# exit
config>router>ospf>area# exit

The following example displays the OSPF configuration with the modifications entered in the previous example:

A:ALU-49>config>router>ospf# info
----------------------------------------------
            asbr
            external-preference 140
            export "OSPF-Export"
            overload
            overload-on-boot timeout 60
            preference 9
            traffic-engineering
            exit
            area 0.0.0.0
                virtual-link 10.0.0.1 transit-area 0.0.0.1
                    authentication-type message-digest
                    message-digest-key 2 md5 "Mi6BQAFi3MI" hash
                exit
                virtual-link 10.2.3.4 transit-area 1.2.3.4
                    hello-interval 9
                    dead-interval 40
                exit
                interface "system"
                exit
            exit
            area 0.0.0.1
            exit
            area 0.0.0.20
                stub
                exit
                interface "to-HQ"
                    priority 50
                exit
            exit
----------------------------------------------
A:ALU-49>config>router>ospf#

OSPF command reference

Command hierarchies

Configuration commands

config
    - router
        - [no] ospf 
            - advertise-router-capability {link | area | as}
            - no advertise-router-capability
            - [no] advertise-tunnel-link
            - [no] area area-id
                - [no] advertise-router-capability
                - area-range ip-prefix/mask [advertise | not-advertise]
                - no area-range ip-prefix/mask
                - [no] blackhole-aggregate
                - interface ip-int-name [secondary]
                - no interface ip-int-name
                    - adjacency-sid label value
                    - no adjacency-sid 
                    - [no] advertise-router-capability
                    - [no] advertise-subnet
                    - auth-keychain name
                    - no auth-keychain
                    - authentication-key {authentication-key | hash-key} [hash | hash2]
                    - no authentication-key
                    - authentication-type {password | message-digest}
                    - no authentication-type
                    - bfd-enable [remain-down-on-failure]
                    - no bfd-enable
                    - dead-interval seconds
                    - no dead-interval
                    - hello-interval seconds
                    - no hello-interval
                    - interface-type {broadcast | point-to-point}
                    - no interface-type
                    - lfa-policy-map route-nh-template template-name
                    - no lfa-policy-map
                    - [no] loopfree-alternate-exclude
                    - message-digest-key key-id md5 {key | hash-key} [hash | hash2]
                    - no message-digest-key key-id
                    - metric metric
                    - no metric
                    - mtu bytes
                    - no mtu
                    - node-sid index index-value 
                    - node-sid label label-value 
                    - no node-sid
                    - [no] passive
                    - priority number
                    - no priority
                    - retransmit-interval seconds
                    - no retransmit-interval
                    - [no] shutdown
                    - [no] sid-protection
                    - transit-delay seconds
                    - no transit-delay
                - [no] loopfree-alternate-exclude
                - [no] nssa 
                    - area-range ip-prefix/mask [advertise | not-advertise]
                    - no area-range ip-prefix/mask
                    - originate-default-route [type-7] [no-adjacency-check]
                    - no originate-default-route 
                    - [no] redistribute-external
                    - [no] summaries
                - [no] stub
                    - default-metric metric
                    - no default-metric
                    - [no] summaries
                - [no] virtual-link router-id transit-area area-id
                    - auth-keychain name
                    - no auth-keychain
                    - authentication-key {authentication-key | hash-key} [hash | hash2]
                    - no authentication-key
                    - authentication-type {password | message-digest}
                    - no authentication-type
                    - dead-interval seconds
                    - no dead-interval
                    - hello-interval seconds
                    - no hello-interval
                    - message-digest-key key-id md5 {key | hash-key} [hash | hash2]
                    - no message-digest-key key-id
                    - retransmit-interval seconds
                    - no retransmit-interval
                    - [no] shutdown
                    - transit-delay seconds
                    - no transit-delay
            - [no] asbr [trace-path domain-id]
            - database-export [identifier id] [bgp-ls-identifier bgp-ls-id]
            - no database-export
            - [no] disable-ldp-sync
            - entropy-label
                - [no] override-tunnel-elc
            - export policy-name [policy-name...(up to 5 max)] 
            - no export
            - external-db-overflow limit seconds 
            - no external-db-overflow
            - external-preference preference
            - no external-preference
            - [no] graceful-restart
                - [no] helper-disable
            - import policy-name [policy-name...(up to 5 max)]
            - no import
            - [no] loopfree-alternates
                - exclude
                    - prefix-policy prefix-policy [prefix-policy...(up to 5 max)] 
                    - no prefix-policy 
                - remote-lfa [max-pq-cost value]
                - no remote-lfa 
                    -  node-protect [max-pq-nodes value]
                    -  no node-protect 
                - ti-lfa [max-sr-frr-labels value]
                - no ti-lfa 
                    -  [no] node-protect 
            - overload [timeout seconds]
            - no overload
            - [no] overload-include-stub
            - overload-on-boot [timeout seconds]
            - no overload-on-boot
            - preference preference
            - no preference
            - reference-bandwidth bandwidth-in-kbps
            - reference-bandwidth [tbps Tera-bps] [gbps Giga-bps] [mbps Mega-bps] [kbps Kilo-bps]
            - no reference-bandwidth
            - router-id ip-address
            - no router-id
            - [no] rsvp-shortcut
            - [no] segment-routing
                - adj-sid-hold seconds
                - no adj-sid-hold
                - backup-node-sid ip-prefix/prefix-length index [0..4294967295]
                - backup-node-sid ip-prefix/prefix-length label [1..4294967295]
                - no backup-node-sid 
                - entropy-label {force-disable | enable}
                - no entropy-label 
                - prefix-sid-range global 
                - prefix-sid-range start-label label-value max-index index-value 
                - no prefix-sid-range
                - [no] shutdown
                - srlb reserved-label-block-name
                - no srlb 
                - tunnel-mtu bytes
                - no tunnel-mtu
                - tunnel-table-pref preference 
                - no tunnel-table-pref
            - [no] shutdown
            - timers
                - lsa-arrival lsa-arrival-time
                - no lsa-arrival
                - lsa-generate max-lsa-wait [lsa-initial-wait [lsa-second-wait]]
                - no lsa-generate
                - spf-wait max-spf-wait [spf-initial-wait spf-initial-wait] [spf-second-wait spf-second-wait]
                - no spf-wait
            - [no] traffic-engineering
            - [no] unicast-import-disable
config
    - router
        - [no] ospf3
            - advertise-router-capability {link | area | as}
            - no advertise-router-capability
            - [no] area area-id
                - [no] advertise-router-capability
                - area-range ipv6-prefix/prefix-length [advertise | not-advertise]
                - no area-range ipv6-prefix/prefix-length
                - [no] blackhole-aggregate
                - interface ip-int-name [secondary]
                - no interface ip-int-name
                    - [no] advertise-router-capability
                    - authentication bidirectional sa-name
                    - authentication inbound sa-name outbound sa-name
                    - no authentication 
                    - bfd-enable [remain-down-on-failure]
                    - no bfd-enable
                    - dead-interval seconds
                    - no dead-interval
                    - hello-interval seconds
                    - no hello-interval
                    - interface-type {broadcast | point-to-point}
                    - no interface-type
                    - lfa-policy-map route-nh-template template-name
                    - no lfa-policy-map
                    - [no] loopfree-alternate-exclude
                    - metric metric
                    - no metric
                    - mtu bytes
                    - no mtu
                    - [no] passive
                    - priority number
                    - no priority
                    - retransmit-interval seconds
                    - no retransmit-interval
                    - [no] shutdown
                    - transit-delay seconds
                    - no transit-delay
                - key-rollover-interval seconds
                - no key-rollover-interval 
                - [no] loopfree-alternate-exclude
                - [no] nssa
                    - area-range ipv6-prefix/prefix-length [advertise | not-advertise]
                    - no area-range ipv6-prefix/prefix-length
                    - originate-default-route [type-nssa] [no-adjacency-check]
                    - no originate-default-route 
                    - [no] redistribute-external
                    - [no] summaries
                - [no] stub
                    - default-metric metric
                    - no default-metric
                    - [no] summaries
                - [no] virtual-link router-id transit-area area-id
                    - authentication bidirectional sa-name
                    - authentication inbound sa-name outbound sa-name
                    - no authentication 
                    - dead-interval seconds
                    - no dead-interval
                    - hello-interval seconds
                    - no hello-interval
                    - retransmit-interval seconds
                    - no retransmit-interval
                    - [no] shutdown
                    - transit-delay seconds
                    - no transit-delay
            - [no] asbr 
            - export policy-name [policy-name...(up to 5 max)]
            - no export
            - external-db-overflow limit seconds 
            - no external-db-overflow
            - external-preference preference
            - no external-preference
            - [no] loopfree-alternates
                - exclude
                    - prefix-policy prefix-policy [prefix-policy...(up to 5 max)] 
                    - no prefix-policy 
            - [no] multicast-import 
            - overload [timeout seconds]
            - no overload
            - [no] overload-include-stub
            - overload-on-boot [timeout seconds]
            - no overload-on-boot
            - preference preference
            - no preference
            - reference-bandwidth bandwidth-in-kbps
            - reference-bandwidth [tbps Tera-bps] [gbps Giga-bps] [mbps Mega-bps] [kbps Kilo-bps]
            - no reference-bandwidth
            - router-id ip-address
            - no router-id
            - [no] shutdown
            - timers
                - lsa-arrival lsa-arrival-time
                - no lsa-arrival
                - lsa-generate max-lsa-wait [lsa-initial-wait [lsa-second-wait]]
                - no lsa-generate
                - spf-wait max-spf-wait [spf-initial-wait spf-initial-wait] [spf-second-wait spf-second-wait] 
                - no spf-wait
            - [no] unicast-import-disable

Show commands

show
    - router [router-instance]
    - router service-name [service-name]
        - ospf [all]
            - area [area-id] [detail] [lfa]
            - capabilities [router-id] 
            - database [type {router | network | summary | asbr-summary | external | nssa | all} [area area-id] [adv-router router-id] [link-state-id] [detail] [filtered] 
            - interface [area area-id] [detail]
            - interface [ip-int-name | ip-address] [detail]
            - interface [ip-int-name | ip-address] database [detail]
            - lfa-coverage
            - neighbor [ip-int-name | ip-address] [detail]
            - neighbor overview
            - neighbor [remote ip-address] [detail]
            - opaque-database [area area-id | as] [adv-router router-id] [ls-id] [detail]
            - prefix-sids [ip-prefix[/prefix-length]] [sid sid] [adv-router router-id]
            - range [area-id]
            - routes [ip-prefix[/prefix-length]] [type] [detail] [alternative] [summary] [exclude-shortcut]
            - sham-link [interface-name] [detail]
            - sham-link interface-name remote ip-address [detail]
            - sham-link-neighbor [detail]
            - sham-link-neighbor interface-name remote ip-address [detail]
            - spf [lfa]
            - statistics
            - status
            - virtual-link database [detail]
            - virtual-link [detail]
            - virtual-neighbor [remote ip-address] [detail]
        - ospf3 [all]
            - area [area-id] [detail] [lfa]
            - capabilities [router-id] 
            - database [type database-type] [area area-id] [adv-router router-id] [link-state-id] [detail] [filtered] 
            - interface [area area-id] [detail]
            - interface [ip-int-name | ip-address | ipv6-address] [detail]
            - interface [ip-int-name | ip-address | ipv6-address] database [detail]
            - lfa-coverage
            - neighbor [ip-int-name] [router-id] [detail]
            - neighbor overview
            - range [area-id]
            - routes [ip-prefix[/pfx-len]] [type] [detail] [alternative] [summary] 
            - spf [lfa]
            - statistics
            - status
            - virtual-link [detail]
            - virtual-neighbor [remote ipv6-address] [detail]

Monitor commands

monitor
    - router
        - ospf
            - interface interface [interface...(up to 5 max)] [interval seconds] [repeat repeat] [absolute | rate]
            - neighbor ip-address [ip-address...(up to 5 max)] [interval seconds] [repeat repeat] [absolute | rate]
            - virtual-link nbr-rtr-id area area-id [interval seconds] [repeat repeat] [absolute | rate]
            - virtual-neighbor nbr-rtr-id area area-id [interval seconds] [repeat repeat] [absolute | rate]
        - ospf3
            - interface interface [interface...(up to 5 max)] [interval seconds] [repeat repeat] [absolute | rate]
            - neighbor router-id ip-int-name [interval seconds] [repeat repeat] [absolute | rate] area area-id
            - virtual-link nbr-rtr-id area area-id [interval seconds] [repeat repeat] [absolute | rate]
            - virtual-neighbor nbr-rtr-id transit-area transit-area [interval seconds] [repeat repeat] [absolute | rate]

Debug commands

debug
    - router
        - ospf
            - area [area-id]
            - no area
            - area-range [ip-address]
            - no area-range
            - cspf [ip-address]
            - no cspf
            - interface [ip-int-name | ip-address]
            - no interface
            - leak [ip-address]
            - no leak
            - lsdb [type] [ls-id] [adv-rtr-id] [area area-id]
            - no lsdb
            - [no] misc
            - neighbor [ip-int-name | router-id]
            - no neighbor
            - nssa-range [ip-address]
            - no nssa-range
            - packet [packet-type] [ip-address]
            - no packet
            - rsvp-shortcut [ip-address]
            - no rsvp-shortcut
            - rtm [ip-address]
            - no rtm
            - sham-neighbor [ip-address]
            - no sham-neighbor
            - spf [type] [dest-addr]
            - no spf
            - virtual-neighbor [ip-address]
            - no virtual-neighbor
        - ospf3
            - area [area-id]
            - no area
            - area-range [ip-address]
            - no area-range
            - interface [ip-int-name | ip-address]
            - no interface
            - leak [ip-address]
            - no leak
            - lsdb [type] [ls-id] [adv-rtr-id] [area area-id]
            - no lsdb
            - [no] misc
            - neighbor [ip-int-name | router-id]
            - no neighbor
            - nssa-range [ip-address]
            - no nssa-range
            - packet [packet-type] [ip-address]
            - no packet
            - rsvp-shortcut [ip-address]
            - no rsvp-shortcut
            - spf [type] [dest-addr]
            - no spf
            - virtual-neighbor [ip-address]
            - no virtual-neighbor

Command descriptions

Configuration commands

Generic commands
shutdown
Syntax

[no] shutdown

Context

config>router>ospf

config>router>ospf>area>interface

config>router>ospf>area>segment-routing

config>router>ospf>area>virtual-link

config>router>ospf3

config>router>ospf3>area>interface

config>router>ospf3>area>virtual-link

Description

This command administratively disables the entity. When disabled, an entity does not change, reset, or remove any configuration settings or statistics. Many entities must be explicitly enabled using the no shutdown command.

The operational state of the entity is disabled as well as the operational state of any entities contained within. Many objects must be shut down before they can be deleted.

Unlike other commands and parameters where the default state is not indicated in the configuration file, shutdown and no shutdown are always indicated in system-generated configuration files.

The no form of the command puts an entity into the administratively enabled state.

Default

OSPF protocol – the OSPF protocol is created in the no shutdown state

OSPF interface – when an IP interface is configured as an OSPF interface, OSPF on the interface is in the no shutdown state by default

Global commands
ospf
Syntax

[no] ospf

Context

config>router

Description

This command activates OSPF on the router and enables access to the context to define OSPF parameters.

Before OSPF can be activated on the router, the router ID must be configured.

The router ID uniquely identifies the router within an AS. In OSPF, routing information is exchanged between autonomous systems, which are groups of networks that share routing information. The router ID can be set to be the same as the system interface address (loopback address).

The router ID is derived by one of the following methods:

  • defining the value using the config>router>router-id ip-address command

  • defining the system interface using the config>router>interface ip-int-name command (used if the router ID is not specified with the config>router>router-id ip-address command)

  • inheriting the last 4 bytes of the MAC address

When configuring a new router ID, protocols are not automatically restarted with the new router ID. The next time a protocol is initialized, the new router ID is used. To force the new router ID, issue the shutdown and no shutdown commands for OSPF or restart the entire router.

The no form of the command reverts to the default value.

Default

no ospf

ospf3
Syntax

[no] ospf3

Context

config>router

Description

This command activates OSPFv3 on the router and enables access to the context to define OSPFv3 parameters.

Before OSPFv3 can be activated on the router, the router ID must be configured.

The router ID uniquely identifies the router within an AS. In OSPFv3, routing information is exchanged between autonomous systems, which are groups of networks that share routing information. The router ID can be set to be the same as the system interface address (loopback address).

The router ID is derived by one of the following methods:

  • defining the value using the config>router>router-id ip-address command

  • defining the system interface using the config>router>interface ip-int-name command (used if the router ID is not specified with the config>router>router-id ip-address command)

  • inheriting the last 4 bytes of the MAC address

When configuring a new router ID, protocols are not automatically restarted with the new router ID. The next time a protocol is initialized, the new router ID is used. To force the new router ID, issue the shutdown and no shutdown commands for OSPFv3 or restart the entire router.

The no form of the command reverts to the default value.

Default

no ospf3

advertise-router-capability
Syntax

advertise-router-capability {link | area | as}

no advertise-router-capability

Context

config>router>ospf

config>router>ospf3

Description

This command enables advertisement of a router's capabilities to its neighbors for informational and troubleshooting purposes. A Router Information (RI) LSA as defined in RFC 4970 advertises the following capabilities:

  • OSPF graceful restart capable: no

  • OSPF graceful restart helper: yes, when enabled

  • OSPF stub router support: yes

  • OSPF traffic engineering support: yes, when enabled

  • OSPF point-to-point over LAN: yes

  • OSPF experimental TE: no

The parameters (link, area and as) control the scope of the capability advertisements.

The no form of this command disables this capability.

Default

no advertise-router-capability

Parameters
link

capabilities are only advertised over local links and not flooded beyond

area

capabilities are only advertised within the area of origin

as

capabilities are advertised throughout the entire autonomous system

advertise-tunnel-link
Syntax

[no] advertise-tunnel-link

Context

config>router>ospf

Description

This command enables the forwarding adjacency feature. With this feature, OSPF advertises an RSVP-TE LSP as a link so that other routers in the network can include it in their SPF calculations. The RSVP-TE LSP is advertised as an unnumbered point-to-point link and the link-state advertisement (LSA) has no traffic engineering opaque sub-TLVs as per RFC 3906.

The forwarding adjacency feature can be enabled independently from the IGP shortcut feature (rsvp-shortcut). If both features are enabled in OSPF, the forwarding adjacency feature takes precedence.

When this feature is enabled, each node advertises a point-to-point unnumbered link for each best-metric tunnel to the router ID of any endpoint node. The node does not include the tunnels as IGP shortcuts in the SPF calculation directly. Instead, when the LSA advertising the corresponding point-to-point unnumbered link is installed in the local routing database, the node performs an SPF calculation using the link like any other link LSA.

The link bidirectional check requires that a regular link or tunnel link exists in the reverse direction for the tunnel to be used in the SPF calculation.

An RSVP-TE LSP can be excluded from being used as a forwarding adjacency with the config>router>mpls>lsp>no igp-shortcut command.

The no form of this command disables forwarding adjacency and therefore disables the advertisement of RSVP-TE LSPs into OSPF.

Default

no advertise-tunnel-link

asbr
Syntax

[no] asbr [trace-path domain-id]

Context

config>router>ospf

config>router>ospf3

Description

This command configures the router as an autonomous system boundary router (ASBR) if the router is to be used to distribute external routes into the OSPF domain. When a router is configured as an ASBR, the export policies into the OSPF domain take effect. If no policies are configured, no external routes are redistributed into the OSPF domain.

The no form of the command removes the ASBR status and withdraws the routes redistributed from the routing table into OSPF from the link-state database.

Only the base OSPF instance is supported; therefore, the domain ID may not need to be configured. However, in order to prevent routing loops (where routes learned from one domain are redistributed back into the domain), the domain ID can be used to tag external LSAs – indicating which domain or network they have learned the route from.

Default

no asbr – the router is not an ASBR

Parameters
domain-id

specifies the domain ID

Values

1 to 31

Default

0x0

database-export
Syntax

database-export [identifier id] [bgp-ls-identifier bgp-ls-id]

no database-export

Context

config>router>ospf

Description

This command enables the population of the extended TE database (TE-DB) with the link-state information from OSPF.

The extended TE-DB is used as a central point for importing all link-state, link, node, and prefix information from IGP instances on the router and exporting the information to BGP-LS on the router. This information includes the IGP, TE, SID sub-TLV, and adjacency SID sub-TLV.

The no form of this command disables database exportation.

Default

no database-export

Parameters
identifier

uniquely identifies the IGP instance in the BGP-LS NLRI when a router has interfaces participating in multiple IGP instances. This parameter defaults to the IGP instance ID assigned by the 7705 SAR. However, because the concept of instance ID defined in IS-IS (RFC 6822) is unique within a routing domain while the one specified for OSPF is significant for the local subnet only (RFC 6549), the user can remove any overlap by configuring the new identifier value to be unique within a particular IGP domain when this router sends the IGP link-state information using BGP-LS.

id

specifies an entry ID to export

Values

0 to 18446744073709551615

bgp-ls-identifier

used with the autonomous system number (ASN) to correlate the BGP-LS NLRI advertisements of multiple BGP-LS speakers in the same IGP domain. If an NRC-P network domain has multiple IGP domains, BGP-LS speakers in each IGP domain must be configured with the same unique tuple {bgp-ls-identifier, asn}.

The BGP-LS identifier is optional and is only sent in a BGP-LS NLRI if configured in the IGP instance of an IGP domain.

If this IGP instance participates in traffic engineering with RSVP-TE or SR-TE, the traffic-engineering option is not strictly required because enabling the extended TE-DB populates this information automatically. However, it is recommended that the enable traffic engineering to make the configuration consistent with other routers in the network that do not require enabling of the extended TE-DB.

bgp-ls-id

specifies a BGP LS ID to export

Values

0 to 4294967295

disable-ldp-sync
Syntax

[no] disable-ldp-sync

Context

config>router>ospf

Description

This command disables the IGP-LDP synchronization feature on all interfaces participating in the OSPF or IS-IS routing protocol. When this command is executed, IGP immediately advertises the actual value of the link cost for all interfaces that have the IGP-LDP synchronization enabled if the currently advertised cost is different. IGP-LDP synchronization will then be disabled for all interfaces. This command does not delete the interface configuration.

The no form of this command restores the default settings and re-enables IGP-LDP synchronization on all interfaces participating in the OSPF or IS-IS routing protocol and for which the ldp-sync-timer is configured (see the 7705 SAR Router Configuration Guide for information about configuring the ldp-sync-timer).

Default

no disable-ldp-sync

entropy-label
Syntax

entropy-label

Context

config>router>ospf

Description

This command enables the context for the configuration of entropy label capabilities for the routing protocol.

override-tunnel-elc
Syntax

[no] override-tunnel-elc

Context

config>router>ospf>entropy-label

Description

This command configures the ability to override any received entropy label capability advertisements. When enabled, the system assumes that all nodes for an IGP domain are capable of receiving and processing the entropy label on segment routed tunnels. This command can only be configured if entropy-label is enabled via the config>router>ospf>segment-routing>entropy-label command.

The no version of this command disables the override. The system assumes entropy label capability for other nodes in the IGP instance if capability advertisements are received.

Default

no override-tunnel-elc

export
Syntax

export policy-name [policy-name…(up to 5 max)]

no export

Context

config>router>ospf

config>router>ospf3

Description

This command specifies export route policies to determine which routes are exported from the routing table manager to OSPF. Export policies are only in effect if OSPF is configured as an ASBR.

If no export policy is specified, non-OSPF routes are not exported from the routing table manager to OSPF.

If multiple policy names are specified, the policies are evaluated in the order they are specified. The first policy that matches is applied. If multiple export commands are issued, the last command entered will override the previous command. A maximum of five policy names can be specified.

The no form of the command removes all policies from the configuration.

See the 7705 SAR Router Configuration Guide for information about defining route policies.

Default

no export

Parameters
policy-name

the export route policy name. Allowed values are any string up to 32 characters long composed of printable, 7-bit ASCII characters. If the string contains special characters (such as #, $, or spaces), the entire string must be enclosed within double quotes.

The specified names must already be defined.

external-db-overflow
Syntax

external-db-overflow limit seconds

no external-db-overflow

Context

config>router>ospf

config>router>ospf3

Description

This command enables limits on the number of non-default, AS-external LSA entries that can be stored in the link-state database (LSDB) and specifies a wait timer before processing these entries after the limit is exceeded.

The limit value specifies the maximum number of entries that can be stored in the LSDB. Placing a limit on these LSAs in the LSDB protects the router from receiving an excessive number of external routes that consume excessive memory or CPU resources. If the number of routes reaches or exceeds the limit, the table is in an overflow state. When in an overflow state, the router will not originate any new AS-external LSAs and will withdraw all the self-originated non-default external LSAs.

The seconds value specifies the time to wait after an overflow state before regenerating and processing non-default, AS-external LSAs. The waiting period acts like a dampening period, preventing the router from continuously running shortest path first (SPF) calculations caused by the excessive number of non-default, AS-external LSAs.

The external-db-overflow must be set identically on all routers attached to any regular OSPF area. OSPF stub areas and not-so-stubby areas (NSSAs) are excluded.

The noform of the command disables limiting the number of non-default, AS-external LSA entries.

Default

no external-db-overflow

Parameters
limit

the maximum number of non-default, AS-external LSA entries that can be stored in the LSDB before going into an overflow state, expressed as a decimal integer

Values

0 to 2147483674

seconds

the number of seconds after entering an overflow state before attempting to process non-default, AS-external LSAs, expressed as a decimal integer

Values

0 to 2147483674

external-preference
Syntax

external-preference preference

no external-preference

Context

config>router>ospf

config>router>ospf3

Description

This command configures the preference for OSPF external routes. The preference for internal routes is set with the preference command.

A route can be learned by the router from different protocols, in which case, the costs are not comparable. When this occurs, the preference is used to decide which route will be used.

Different protocols should not be configured with the same preference. If this occurs, the tiebreaker is based on the default preferences as defined in the following table.

Table 6. Route preference defaults by route type

Route type

Preference

Configurable

Direct attached

0

No

Static routes

5

Yes

OSPF internal

10

Yes

IS-IS level 1 internal

15

Yes

IS-IS level 2 internal

18

Yes

OSPF external

150

Yes

IS-IS level 1 external

160

Yes

IS-IS level 2 external

165

Yes

If multiple routes are learned with the same preference using the same protocol, the lowest-cost route is used. If multiple routes are learned with the same preference using the same protocol and the costs (metrics) are equal, the decision of which route to use is determined by the configuration of ECMP in the config>router context. See the 7705 SAR Router Configuration Guide for information about ECMP.

Note: To configure a preference for static routes, use the config>router>static-route-entry context. See the 7705 SAR Router Configuration Guide for information.

The no form of the command reverts to the default value.

Default

external-preference 150 – OSPF external routes have a default preference of 150

Parameters
preference

the preference for external routes, expressed as a decimal integer

Values

1 to 255

graceful-restart
Syntax

[no] graceful-restart

Context

config>router>ospf

Description

This command enables or disables graceful restart for OSPF. Graceful restart is not fully implemented on the 7705 SAR, meaning that the router will never request graceful restart support from its neighbors. However, graceful restart must be enabled before the 7705 SAR can be configured for graceful restart helper mode.

The no form of the command disables graceful restart and removes all graceful restart configurations in OSPF.

Default

no graceful-restart

helper-disable
Syntax

[no] helper-disable

Context

config>router>ospf>graceful-restart

Description

This command enables or disables graceful restart helper mode for OSPF. In helper mode, if a grace LSA is received from an OSPF neighbor, the 7705 SAR keeps the link toward that neighbor up and operational until the specified grace period in the grace LSA expires or the graceful restart is successful, whichever comes first.

The no form of the command enables graceful restart helper mode and is the default when graceful-restart is enabled.

Default

no helper-disable

import
Syntax

import policy-name [policy-name...(up to 5 max)]

no import

Context

config>router>ospf

Description

This command configures up to five import route policies that determine which routes are imported into the routing table.

When a prefix received in an OSPF LSA is accepted by an entry in an OSPF import policy, it is installed in the routing table if it is the most preferred route to the destination. When a prefix received in an OSPF LSA is rejected by an entry in an OSPF import policy, it is not installed in the routing table, even if it has the lowest preference value among all the routes to that destination.

The flooding of LSAs is not affected by OSPF import policy actions.

The no form of this command removes all import policies from the configuration. The default behavior then applies, that is, if an OSPF route has the lowest preference value among all routes to the destination, it is installed in the routing table.

Default

no import

Parameters
policy-name

specifies the import route policy name. Allowed values are any string up to 32 characters long composed of printable, 7-bit ASCII characters. If the string contains special characters (such as #, $, or spaces), the entire string must be enclosed within double quotes.

The route policy names must already be defined.

loopfree-alternates
Syntax

[no] loopfree-alternates

Context

config>router>ospf

config>router>ospf3

Description

This command enables loop-free alternate (LFA) computation by SPF under the OSPFv2 or OSPFv3 routing protocol context.

When this command is enabled, it instructs the IGP SPF to attempt to precalculate both a primary next hop and an LFA backup next hop for every learned prefix. When found, the LFA next hop is populated in the routing table along with the primary next hop for the prefix.

The no form of this command disables LFA computation by the IGP SPF.

Default

no loopfree-alternates

exclude
Syntax

exclude

Context

config>router>ospf>loopfree-alternates

config>router>ospf3>loopfree-alternates

Description

This command enables the context for identifying prefix policies to be excluded from the LFA calculation by OSPF.

prefix-policy
Syntax

prefix-policy prefix-policy [prefix-policy…(up to 5 max)]

no prefix-policy

Context

config>router>ospf>loopfree-alternates>exclude

config>router>ospf3>loopfree-alternates>exclude

Description

This command excludes from the LFA SPF calculation any prefixes that match a prefix entry in a prefix policy. If a prefix is excluded, it is not included in the LFA SPF calculation, regardless of its priority.

Prefix policies are created with the config>router>policy-options>prefix-list command. For information about prefix lists, see the 7705 SAR Router Configuration Guide, ‟Route Policies”.

The default action of the loopfree-alternates>exclude>prefix-policy command, when not explicitly specified in the prefix policy, is to ‟reject”. Therefore, even if the default-action reject statement was not explicitly stated for the prefix policy, a prefix that does not match any entry in the policy will be used in the LFA SPF calculation

The no form of this command removes the excluded prefix policy.

Default

no prefix-policy

Parameters
prefix-policy

the name of the prefix policy to be excluded from the LFA SPF calculation for OSPF. Up to five prefixes can be specified. The specified prefix policy must already be defined.

remote-lfa
Syntax

remote-lfa [max-pq-cost value]

no remote-lfa

Context

config>router>ospf>loopfree-alternates

Description

This command enables the use of the remote LFA algorithm in the LFA SPF calculation in OSPF.

When this command is enabled, SPF performs the additional remote LFA computation that follows the regular LFA next-hop calculation when the latter calculation results in no protection for one or more prefixes that are resolved to a particular interface.

Remote LFA extends the protection coverage of LFA-FRR to any topology by automatically computing and establishing or tearing down shortcut tunnels, also referred to as repair tunnels, to a remote LFA node that puts the packets back into the shortest path without looping them back to the node that forwarded them over the repair tunnel. The remote LFA node is referred to as a PQ node. A repair tunnel can, in theory, be an RSVP-TE LSP, an LDP-in-LDP tunnel, or a segment routing (SR) tunnel. The remote-lfa command is restricted to using an SR repair tunnel to the remote LFA node.

The remote LFA algorithm is a per-link LFA SPF calculation and not a per-prefix calculation like the regular LFA algorithm. The remote LFA algorithm provides protection for all destination prefixes that share the protected link by using the neighbor on the other side of the protected link as a proxy for all the destinations.

The no form of this command disables the use of the remote LFA algorithm in the LFA SPF calculation in OSPF.

Default

no remote-lfa

Parameters
value

specifies the integer used to limit the search for candidate P and Q nodes in the remote LFA algorithm by setting the maximum IGP cost from the router performing the remote LFA calculation to the candidate P or Q node

Values

0 to 4294967295

Default

4261412864

node-protect
Syntax

node-protect [max-pq-nodes value]

no node-protect

Context

config>router>ospf>loopfree-alternates>remote-lfa

config>router>ospf>loopfree-alternates>ti-lfa

Description

This command administratively enables the use of the node-protect calculation in the remote LFA algorithm or topology-independent LFA (TI-LFA) algorithm in SPF computations. When node protection is enabled, the router prefers a node-protect repair tunnel over a link-protect repair tunnel for a particular prefix if both tunnels are found in the remote LFA or TI-LFA SPF computation. However, the SPF computations may only find a link-protect repair tunnel for prefixes owned by the protected node.

The max-pq-nodes parameter controls the maximum number of candidate PQ nodes found in the LFA SPFs for which the node protection check is performed. The node-protect condition means that the router must run the original link-protect remote LFA algorithm plus one extra forward SPF on behalf of each PQ node found, potentially after applying the max-pq-cost parameter, to verify that the path from the PQ node to the destination does not traverse the protected node. Setting the max-pq-nodes parameter to a lower value means that the LFA SPFs use less computation time and resources; however, this may result in not finding a node-protect repair tunnel.

Note: The optional max-pq-nodes parameter is available only in the config>router> ospf>loopfree-alternates>remote-lfa context.

The no form of the command disables the node-protect calculation.

Default

no node-protect

Parameters
value

specifies the maximum number of PQ nodes found in the LFA SPFs for which the node protection check is performed

Values

1 to 32

Default

16

ti-lfa
Syntax

ti-lfa [max-sr-frr-labels value]

no ti-lfa

Context

config>router>ospf>loopfree-alternates

Description

This command enables the use of the topology-independent LFA (TI-LFA) algorithm in the LFA SPF calculation in OSPF.

The TI-LFA algorithm improves the protection coverage of a network topology by computing and automatically instantiating a repair tunnel to a Q node that is not in the shortest path from the computing node. The repair tunnel uses the shortest path to the P node and a source-routed path from the P node to the Q node.

The TI-LFA repair tunnel can have a maximum of three labels pushed in addition to the label of the destination node or prefix. The user can set a lower maximum value for the additional FRR labels by configuring the max-sr-frr-labels option.

The no form of this command disables the use of the TI-LFA algorithm in the LFA SPF calculation in OSPF.

Default

no ti-lfa

Parameters
value

specifies the maximum number of labels that the TI-LFA backup next hop can use. The TI-LFA algorithm uses this value to limit the search for the Q node from the P node on the post-convergence path.

Values

0 to 3

Default

2

multicast-import
Syntax

[no] multicast-import

Context

config>router>ospf

config>router>ospf3

Description

This command administratively enables the submission of routes into the multicast RTM by OSPF.

The no form of the command disables the submission of routes into the multicast RTM.

Default

no multicast-import

overload
Syntax

overload [timeout seconds]

no overload

Context

config>router>ospf

config>router>ospf3

Description

This command changes the overload state of the local router so that it appears to be overloaded. When overload is enabled, the router can participate in OSPF routing, but is not used for transit traffic. Traffic destined for directly attached interfaces continues to reach the router.

To put the IGP in an overload state, enter a timeout value. The IGP will enter the overload state until the timeout timer expires or a no overload command is executed.

If no timeout is specified, the overload state is maintained indefinitely.

If the overload command is encountered during the execution of an overload-on-boot command, the overload command takes precedence. This situation could occur as a result of a saved configuration file where both parameters are saved. When the file is saved by the system, the overload-on-boot command is saved after the overload command.

Use the no form of this command to return to the default. When the no overload command is executed, the overload state is terminated regardless of the reason the protocol entered the overload state.

Default

no overload

Parameters
seconds

the number of seconds to reset overloading

Values

1 to 1800

overload-include-stub
Syntax

[no] overload-include-stub

Context

config>router>ospf

config>router>ospf3

Description

This command is used to determine if the OSPF stub networks should be advertised with a maximum metric value when the system goes into an overload state for any reason. When enabled, the system uses the maximum metric value. When this command is enabled and the router is in overload, all stub interfaces, including loopback and system interfaces, will be advertised at the maximum metric.

Default

no overload-include-stub

overload-on-boot
Syntax

overload-on-boot [timeout seconds]

no overload-on-boot

Context

config>router>ospf

config>router>ospf3

Description

When the router is in an overload state, the router is used only if there is no other router to reach the destination. This command configures OSPF upon boot-up in the overload state until one of the following events occurs:

  • the timeout timer expires (if a timeout has been specified)

  • a manual override of the current overload state is entered with the no overload command

If no timeout is specified, the overload state is maintained indefinitely.

The no overload command does not affect the overload-on-boot function.

The no form of the command removes the overload-on-boot functionality from the configuration.

Default

no overload-on-boot

Parameters
seconds

the number of seconds to reset overloading

Values

1 to 1800

preference
Syntax

preference preference

no preference

Context

config>router>ospf

config>router>ospf3

Description

This command configures the preference for OSPF internal routes.

A route can be learned by the router from different protocols, in which case, the costs are not comparable. When this occurs, the preference is used to decide which route will be used.

Different protocols should not be configured with the same preference. If this occurs, the tiebreaker is based on the default preferences as defined in Route preference defaults by route type . If multiple routes are learned with the same preference using the same protocol and the costs (metrics) are equal, the decision of which route to use is determined by the configuration of ECMP in the config>router context. See the 7705 SAR Router Configuration Guide for information about ECMP.

The no form of the command reverts to the default value.

Default

preference 10 – OSPF internal routes have a preference of 10

Parameters
preference

the preference for internal routes, expressed as a decimal integer

Values

1 to 255

reference-bandwidth
Syntax

reference-bandwidth bandwidth-in-kbps

reference-bandwidth [tbps Tera-bps] [gbps Giga-bps] [mbps Mega-bps] [kbps Kilo-bps]

no reference-bandwidth

Context

config>router>ospf

config>router>ospf3

Description

This command configures the reference bandwidth used to calculate the default costs of interfaces based on their underlying link speed.

The default interface cost is calculated as follows:

cost = reference bandwidth/bandwidth

The default reference bandwidth is 100 000 000 kb/s or 100 Gb/s; therefore, the default auto-cost metrics for various link speeds are as follows:

  • 10 Mb/s link: default cost of 10000

  • 100 Mb/s link: default cost of 1000

  • 1 Gb/s link: default cost of 100

  • 10 Gb/s link: default cost of 10

The reference-bandwidth command assigns a default cost to the interface based on the interface speed. To override this default cost on a particular interface, use the metric metric command in the config>router>ospf>area>interface ip-int-name or config>router> ospf3>area>interface ip-int-name context.

The no form of the command resets the reference bandwidth to the default value.

Default

reference-bandwidth 100000000

Parameters
bandwidth-in-kbps

the reference bandwidth in kilobits per second, expressed as a decimal integer

Values

1 to 4000000000

Tera-bps

the reference bandwidth in terabits per second, expressed as a decimal integer

Values

1 to 4

Giga-bps

the reference bandwidth in gigabits per second, expressed as a decimal integer

Values

1 to 999

Mega-bps

the reference bandwidth in megabits per second, expressed as a decimal integer

Values

1 to 999

Kilo-bps

the reference bandwidth in kilobits per second, expressed as a decimal integer

Values

1 to 999

router-id
Syntax

router-id ip-address

no router-id

Context

config>router>ospf

config>router>ospf3

Description

This command configures the router ID to be used under the global routing table context (GRT). The 7705 SAR supports a single OSPF instance in the GRT context; therefore, changing the router ID has a global implication.

When configuring the router ID in the base instance of OSPF, the value overrides the router ID configured in the config>router context.

The default value for the base instance is inherited from the configuration in the config>router context. If the router ID in the config>router context is not configured, the following applies:

  • the system uses the system interface address (which is also the loopback address)

  • if a system interface address is not configured, the last 4 bytes of the chassis MAC address are used

When configuring a new router ID, the instance is not automatically restarted with the new router ID. The next time the instance is initialized, the new router ID is used.

To force the new router ID to be used, issue the shutdown and no shutdown commands for the instance, or reboot the entire router.

The no form of the command reverts to the default value.

Default

0.0.0.0 (base OSPF)

Parameters
ip-address

a 32-bit, unsigned integer uniquely identifying the router in the autonomous system

rsvp-shortcut
Syntax

[no] rsvp-shortcut

Context

config>router>ospf

Description

This command enables the use of an RSVP-TE shortcut for resolving OSPF routes. When the command is enabled, OSPF includes RSVP-TE LSPs originating on this node and terminating on the router ID of a remote node as direct links with a metric equal to the operational metric provided by MPLS.

The SPF algorithm will always use the IGP metric to build the SPF tree, and the LSP metric value does not update the SPF tree calculation. During the IP reach to determine the reachability of nodes and prefixes, LSPs are overlaid and the LSP metric is used to determine the subset of paths that are of an equal lowest cost to reach a node or a prefix. If the relative-metric option for this LSP is enabled (in the config>router>mpls>lsp>igp-shortcut context), OSPF will apply the shortest cost between the endpoints of the LSP plus the value of the offset, instead of the LSP operational metric, when calculating the cost of a prefix that is resolved to the LSP.

When a prefix is resolved to a tunnel next hop, the packet is sent labeled with the label stack corresponding to the NHLFE of the RSVP-TE LSP. Any network event that causes an RSVP-TE LSP to go down will trigger a full SPF calculation, which may result in a new route being installed over another RSVP-TE LSP shortcut as a tunnel next hop or over a regular IP next hop.

When the rsvp-shortcut command is enabled, all RSVP-TE LSPs originating on this node are eligible by default as long as the destination address of the LSP, as configured with the config>router>mpls> lsp>to command, corresponds to a router ID of a remote node. A specific LSP can be excluded from being used as a shortcut with the config>router>mpls>lsp>no igp-shortcut command.

If ECMP is enabled on the system and multiple equal-cost paths exist for the route over a set of tunnel next hops (based on the hashing routine supported for IPv4 packets), there are two possibilities:

  • if the destination is the tunnel endpoint, the system selects the tunnel with the lowest tunnel ID (the IP next hop is never used)

  • if the destination is different from the tunnel endpoint, the system:

    • selects tunnel endpoints where the LSP metric is lower than the IGP cost

    • prefers tunnel endpoints over IP next hops

ECMP is not performed across both the IP and tunnel next hops.

OSPF can populate the multicast RTM with the prefix IP next hop when both rsvp-shortcut and node-protect are enabled. The unicast RTM can still use the tunnel next hop for the same prefix.

The forwarding adjacency feature (advertise-tunnel-link) can be enabled independently from the shortcuts feature. If both features are enabled in OSPF, the forwarding adjacency feature takes precedence.

The no form of this command disables the resolution of IGP routes using RSVP shortcuts.

Default

no rsvp-shortcut

segment-routing
Syntax

[no] segment-routing

Context

config>router>ospf

Description

This command enables the context to configure segment routing parameters within an IGP instance.

Segment routing adds to IS-IS and OSPF routing protocols the ability to perform shortest path routing and source routing using the concept of abstract segment. An abstract segment can represent a local prefix of a node, a specific adjacency of the node (interface or next hop), a service context, or a specific explicit path over the network. For each segment, the IGP advertises an identifier referred to as a segment ID (SID).

Note: Segment routing is supported only in OSPFv2 for IPv4.

When segment routing is used together with the MPLS data plane, the SID is a standard MPLS label. A router forwarding a packet using segment routing will push one or more MPLS labels.

Segment routing using MPLS labels can be used in both shortest path routing applications and traffic engineering applications. On the 7705 SAR, segment routing implements the shortest path forwarding application.

After segment routing is successfully enabled in the IS-IS instance or in OSPF, the router will perform the following operations:

  • advertise the Segment Routing Capability sub-TLV to routers in all areas or levels of the IGP instance. However, only neighbors with which the IGP instance established an adjacency will interpret the SID and label range information and use it for calculating the label to swap to or push for a particular resolved prefix SID.

  • advertise the assigned index for each configured node SID in the new prefix SID sub-TLV with the N-flag (node SID flag) set. The segment routing module then programs the incoming label map (ILM) with a pop operation for each local node SID in the data path.

  • automatically assign and advertise an adjacency SID label for each formed adjacency over a network IP interface in the new adjacency SID sub-TLV. The segment routing module programs the incoming label map (ILM) with a pop operation, in effect with a swap to an implicit null label operation, for each advertised adjacency SID.

  • resolve received prefixes, and if a prefix SID sub-TLV exists, the segment routing module programs the ILM with a swap operation and programs an LSP ID to NHLFE (LTN) with a push operation, both pointing to the primary/LFA NHLFE. An SR tunnel is also added to the TTM.

When the user enables segment routing in an IGP instance, the main SPF and LFA SPF are computed normally and the primary next hop and LFA backup next hop for a received prefix are added to the RTM without the label information advertised in the prefix SID sub-TLV.

adj-sid-hold
Syntax

adj-sid-hold seconds

no adj-sid-hold

Context

config>router>ospf>segment-routing

Description

This command configures a timer to hold the ILM or LTN of an adjacency SID following a failure of the adjacency.

When an adjacency to a neighbor fails, the IGP will withdraw the advertisement of the link TLV information as well as its adjacency SID sub-TLV. However, the LTN or ILM record of the adjacency SID must be kept in the data path to maintain forwarding using the LFA or remote LFA backup for sufficient length of time to allow the ingress LER and other routers that use this adjacency SID to activate a new path after the IGP converges.

If the adjacency is restored before the timer expires, the timer is aborted as soon as the new ILM or LTN records are updated with the new primary and backup NHLFE information.

The no form of the command removes the adjacency SID hold time.

Default

adj-sid-hold 15

Parameters
seconds

the adjacency SID hold time, in seconds

Values

1 to 300

backup-node-sid
Syntax

backup-node-sid ip-prefix/prefix-length index [0..4294967295]

backup-node-sid ip-prefix/prefix-length label [1..4294967295]

no backup-node-sid

Context

config>router>ospf>segment-routing

Description

This command enables LFA protection using a segment routing backup node SID.

The objective of this feature is to reduce the label stack pushed in an LFA tunnel next hop of inter-area and inter-domain prefixes. This is applicable in MPLS deployments across multiple IGP areas or domains such as in seamless MPLS design.

The user enables the feature by configuring a backup node SID at an ABR/ASBR that is acting as a backup to the primary exit ABR/ASBR of inter-area or inter-as routes learned as BGP labeled routes. The user can enter either a label or an index for the backup node SID.

When a node in an IGP domain resolves a BGP label route for an inter-area or inter-domain prefix via the primary ABR exit router, the node will use the backup node SID of the primary ABR exit router, which is advertised by the backup ABR/ASBR, as the LFA backup—instead of the SID to the remote LFA PQ node—to save on the pushed label stack.

This feature only allows the configuration of a single backup node SID per IGP instance and per ABR/ASBR. In other words, only a pair of ABR/ASBR nodes can back up each other in an IGP domain. Each time the user invokes the backup-node-sid command within the same IGP instance, it overrides any previous configuration of the backup node SID. The same ABR/ASBR can, however, participate in multiple IGP instances and provide backup support within each instance.

Default

no backup-node-sid

Parameters
ip-prefix/ip-prefix-length

the IPv4 or IPv6 address prefix

index

specifies the index for this backup node SID

Values

0 to 4294967295

label

specifies the SID value for this backup node SID

Values

1 to 4294967295

entropy-label
Syntax

entropy-label {force-disable | enable}

no entropy-label

Context

config>router>ospf>segment-routing

Description

This command, when used with the force-disable keyword, instructs the system to ignore any received IGP advertisements of entropy label capability relating to remote nodes in the network. The command also prevents a user from configuring override-tunnel-elc for the IGP instance.

The no version of this command enables the processing of any received IGP advertisements of entropy label capability. Using the enable keyword has the same effect.

Default

entropy-label enable

Parameters
force-disable

forces the system to ignore any received advertisements of entropy label capability signaled in the IGP

enable

enables the system to process any received advertisements of entropy label capability signaled in the IGP

prefix-sid-range
Syntax

prefix-sid-range global

prefix-sid-range start-label label-value max-index index-value

no prefix-sid-range

Context

config>router>ospf>segment-routing

Description

This command configures the prefix SID index range and offset label value for an IGP instance.

The key parameter is the configuration of the prefix SID index range and the offset label value that this IGP instance will use. Because each prefix SID represents a network global IP address, the SID index for a prefix must be unique network-wide. Therefore, all routers in the network are expected to configure and advertise the same prefix SID index range for an IGP instance. However, the label value used by each router to represent this prefix, that is, the label programmed in the ILM, can be local to that router by the use of an offset label, referred to as a start label:

Local Label (Prefix SID) = start-label + {SID index}

The label operation in the network is very similar to LDP when operating in independent label distribution mode (RFC 5036, LDP Specification), with the difference being that the label value used to forward a packet to each downstream router is computed by the upstream router based on the advertised prefix SID index using the above formula.

There are two mutually exclusive modes of operation for the prefix SID range on the router: global mode and per-instance mode.

In global mode, the user configures the global keyword and the IGP instance assumes that the start label value is the lowest label value in the SRGB and the prefix SID index range size is equal to the range size of the SRGB. When one IGP instance selects the global option for the prefix SID range, all IGP instances on the system must do the same. The user must shut down the segment routing context and disable the prefix-sid-range command in all IGP instances in order to change the SRGB. When the SRGB is changed, the user must re-enable the prefix-sid-range command. The SRGB range change will fail if an already allocated SID index/label goes out of range.

In per-instance mode, the user partitions the SRGB into non-overlapping sub-ranges among the IGP instances. The user configures a subset of the SRGB by specifying the start label value and the prefix SID index range size. All resulting net label values (start-label + index) must be within the SRGB or the configuration will fail. The 7705 SAR checks for overlaps of the resulting net label value range across IGP instances and will strictly enforce no overlapping of these ranges. The user must shut down the segment routing context of an IGP instance in order to change the SID index/label range of that IGP instance using the prefix-sid-range command. A range change will fail if an already allocated SID index/label goes out of range. The user can change the SRGB without shutting down the segment routing context as long as it does not reduce the current per-IGP instance SID index/label range defined with the prefix-sid-range command. Otherwise, shut down the segment routing context of the IGP instance, and disable and re-enable the prefix-sid-range command.

Default

no prefix-sid-range

Parameters
label-value

specifies the label offset for the SR label range of this IGP instance

Values

0 to 524287

index-value

specifies the maximum value of the prefix SID index range for this IGP instance

Values

1 to 524287

srlb
Syntax

srlb reserved-label-block-name

no srlb

Context

config>router>ospf>segment-routing

Description

This command specifies the reserved label block to use for the segment routing local block (SRLB) for this OSPF instance. The reserved label block must first be configured in the config>router>mpls-labels context.

The no form of the command removes the SRLB.

Default

no srlb

Parameters
reserved-label-block-name

the name of the reserved label block

tunnel-mtu
Syntax

tunnel-mtu bytes

no tunnel-mtu

Context

config>router>ospf>segment-routing

Description

This command configures the MTU of all SR tunnels within each IGP instance.

The MTU of an SR tunnel populated into the TTM is determined in the same way as the MTU of an IGP tunnel (for example, for an LDP LSP), based on the outgoing interface MTU minus the label stack size. Remote LFA can add, at most, one more label to the tunnel for a total of two labels. There is no default value for this command. If the user does not configure an SR tunnel MTU, the MTU, in bytes, is determined by IGP as explained below.

SR_Tunnel_MTU = MIN {Cfg_SR_MTU, IGP_Tunnel_MTU- (1 + frr-overhead)*4}

where:

  • Cfg_SR_MTU is the MTU configured by the user for all SR tunnels within an IGP instance using the above CLI. If no value was configured by the user, the SR tunnel MTU will be fully determined by the IGP interface calculation explained next.

  • IGP_Tunnel_MTU is the minimum of the IS-IS or OSPF interface MTU among all the ECMP paths or among the primary and LFA backup paths of this SR tunnel.

  • frr-overhead is set to 1 if segment-routing and remote-lfa options are enabled in the IGMP instance. Otherwise, it is set to 0.

The SR tunnel MTU is dynamically updated anytime any of the above parameters used in its calculation changes. This includes when the set of the tunnel next hops changes or the user changes the configured SR MTU or interface MTU value.

Default

no tunnel-mtu

Parameters
bytes

specifies the size of the MTU in bytes

Values

512 to 9198

Default

none

tunnel-table-pref
Syntax

tunnel-table-pref preference

no tunnel-table-pref

Context

config>router>ospf>segment-routing

Description

This command configures the TTM preference of shortest path SR tunnels created by the IGP instance. This is used for BGP shortcuts, VPRN autobind, or BGP transport tunnel when the tunnel binding commands are configured to the any value, which parses the TTM for tunnels in the protocol preference order. The user can choose to either accept the global TTM preference or explicitly list the tunnel types they want to use. If the user lists the tunnel types explicitly, the TTM preference is still used to select one type over the other. In both cases, a fallback to the next preferred tunnel type is performed if the selected type fails. A reversion to a more preferred tunnel type is performed as soon as one is available.

The segment routing module adds to the TTM an SR tunnel entry for each resolved remote node SID prefix and programs the data path having the corresponding LTN with the push operation pointing to the primary and LFA backup NHLFEs.

The default preference for shortest path SR tunnels in the TTM is set lower than LDP tunnels but higher than BGP tunnels to allow controlled migration of customers without disrupting their current deployment when they enable segment routing. The following is the value of the default preference for the various tunnel types. This includes the preference of SR tunnels based on shortest path (referred to as SR-ISIS and SR-OSPF).

Note: The preference of SR-TE LSP is not configurable and is the second most preferred tunnel type after RSVP-TE. This is independent if the SR-TE LSP was resolved in IS-IS or OSPF.
The global default TTM preference for the tunnel types is as follows:

ROUTE_PREF_RSVP

 7

ROUTE_PREF_SR_TE

 8

ROUTE_PREF_LDP

 9

ROUTE_PREF_SR_OSPF_TTM

 10

ROUTE_PREF_SR_ISIS_TTM

 11

ROUTE_PREF_BGP_TTM

 12

ROUTE_PREF_GRE

 255

The default value for SR-ISIS is the same regardless of whether one or more IS-IS instances programmed a tunnel for the same prefix. The selection of an SR tunnel in this case is based on the lowest IGP instance ID.

Default

tunnel-table-pref 10

Parameters
preference

specifies the integer value to represent the preference of OSPF SR tunnels in the TTM

Values

1 to 255

timers
Syntax

timers

Context

config>router>ospf

config>router>ospf3

Description

This command enables the context that allows for the configuration of OSPF timers. Timers control the delay between receipt of a link-state advertisement (LSA) requiring an SPF calculation and the minimum time between successive SPF calculations.

Changing the timers affects CPU usage and network reconvergence times. Lower values reduce reconvergence time but increase CPU usage. Higher values reduce CPU usage but increase reconvergence time.

Default

n/a

lsa-arrival
Syntax

lsa-arrival lsa-arrival-time

no lsa-arrival

Context

config>router>ospf>timers

config>router>ospf3>timers

Description

This command defines the minimum delay that must pass between receipt of the same link-state advertisements (LSAs) arriving from neighbors.

It is recommended that the configured lsa-generate lsa-second-wait interval for the neighbors be equal to or greater than the lsa-arrival-time.

Note: The OSPF timer granularity is 10 ms if the value is less than 500 ms, and 100 ms if the value is equal to 500 ms. Timer values are rounded down to the nearest granularity; for example, a configured value of 550 ms is internally rounded down to 500 ms.

Use the no form of this command to return to the default.

Default

no lsa-arrival

Parameters
lsa-arrival-time

the timer in milliseconds. Values entered that do not match this requirement will be rejected.

Values

0 to 600000

lsa-generate
Syntax

lsa-generate max-lsa-wait [lsa-initial-wait [lsa-second-wait]]

no lsa-generate

Context

config>router>ospf>timers

config>router>ospf3>timers

Description

This command customizes the throttling of OSPF LSA generation. Timers that determine when to generate the first, second, and subsequent LSAs can be controlled with this command. Subsequent LSAs are generated at increasing intervals of the lsa-second-wait timer until a maximum value is reached.

It is recommended that the lsa-arrival-time be equal to or less than the lsa-second-wait interval.

Note: The OSPF timer granularity is 10 ms if the value is less than 500 ms, and 100 ms if the value is equal to 500 ms. Timer values are rounded down to the nearest granularity; for example, a configured value of 550 ms is internally rounded down to 500 ms.

Use the no form of this command to return to the default.

Default

no lsa-generate

Parameters
max-lsa-wait

the maximum interval, in milliseconds, between two consecutive occurrences of an LSA being generated

Values

10 to 600000

Default

5000

lsa-initial-wait

the first waiting period between LSAs generated, in milliseconds. When the LSA exceeds the lsa-initial-wait timer value and the topology changes, there is no wait period and the LSA is immediately generated.

When an LSA is generated, the initial wait period commences. If, within the specified lsa-initial-wait period, another topology change occurs, the lsa-initial-wait timer applies.

Values

10 to 600000

Default

5000

lsa-second-wait

the hold time, in milliseconds, between the first and second LSA generation. The next topology change is subject to this second wait period. With each subsequent topology change, the wait time doubles (that is, two times the previous wait time). This assumes that each failure occurs within the relevant wait period.

Values

10 to 600000

Default

5000

spf-wait
Syntax

spf-wait max-spf-wait [spf-initial-wait spf-initial-wait] [spf-second-wait spf-second-wait]

no spf-wait

Context

config>router>ospf>timers

config>router>ospf3>timers

Description

This command defines the maximum interval between two consecutive SPF calculations in milliseconds. Timers that determine when to initiate the first, second, and subsequent SPF calculations after a topology change occurs can be controlled with this command. Subsequent SPF runs (if required) will occur at exponentially increasing intervals of the spf-second-wait interval. For example, if the spf-second-wait interval is 1000, the next SPF will run after 2000 ms, and the next SPF will run after 4000 ms, and so on, until it reaches the spf-wait value. The SPF interval will stay at the spf-wait value until there are no more SPF runs scheduled in that interval. After a full interval without any SPF runs, the SPF interval will drop back to spf-initial-wait.

Note: The OSPF timer granularity is 10 ms if the value is less than 500 ms, and 100 ms if the value is equal to 500 ms. Timer values are rounded down to the nearest granularity; for example, a configured value of 550 ms is internally rounded down to 500 ms.

Use the no form of this command to return to the default.

Default

no spf-wait

Parameters
max-spf-wait

the maximum interval, in milliseconds, between two consecutive SPF calculations

Values

10 to 120000

Default

1000

spf-initial-wait

the initial SPF calculation delay, in milliseconds, after a topology change

Values

10 to 100000

Default

1000

spf-second-wait

the hold time, in milliseconds, between the first and second SPF calculation

Values

10 to 100000

Default

1000

traffic-engineering
Syntax

[no] traffic-engineering

Context

config>router>ospf

Description

This command enables traffic engineering route calculations constrained by nodes or links.

Traffic engineering enables the router to perform route calculations constrained by nodes or links. The traffic engineering capabilities of this router are limited to calculations based on link and nodal constraints.

The no form of the command disables traffic engineered route calculations.

Default

no traffic-engineering

unicast-import-disable
Syntax

[no] unicast-import-disable

Context

config>router>ospf

config>router>ospf3

Description

This command allows one IGP to import its routes into the multicast RTM (also known as the RPF RTM [Reverse Path Forwarding - Route Table Manager]) while another IGP imports routes only into the unicast RTM. Import policies can redistribute routes from an IGP protocol into the RPF RTM. By default, the IGP routes will not be imported into the RPF RTM, since such an import policy must be explicitly configured.

The no form of the command enables importing IGP routes into the RPF RTM.

Default

disabled (unicast-import-disable)

Area commands
area
Syntax

[no] area area-id

Context

config>router>ospf

config>router>ospf3

Description

This command enables the context to configure an OSPF area. An area is a collection of network segments within an AS that have been administratively grouped together. The area ID can be specified in dotted-decimal notation or as a 32-bit decimal integer.

The no form of the command deletes the specified area from the configuration. Deleting the area also removes the OSPF configuration of all the interfaces, virtual links, address ranges, and so on, that are currently assigned to this area.

The 7705 SAR supports a maximum of four areas.

Default

no area – no OSPF areas are defined

Parameters
area-id

the OSPF area ID expressed in dotted-decimal notation or as a 32-bit decimal integer

Values

0.0.0.0 to 255.255.255.255 (dotted-decimal) 0 to 4294967295 (decimal integer)

advertise-router-capability
Syntax

[no] advertise-router-capability

Context

config>router>ospf>area

config>router>ospf>area>interface

config>router>ospf3>area

config>router>ospf3>area>interface

Description

This command enables advertisement of a router’s capabilities to its neighbors for informational and troubleshooting purposes. A Router Information (RI) LSA as defined in RFC 4970 advertises the following capabilities:

  • OSPF graceful restart capable: no

  • OSPF graceful restart helper: yes, when enabled

  • OSPF stub router support: yes

  • OSPF traffic engineering support: yes, when enabled

  • OSPF point-to-point over LAN: yes

  • OSPF experimental TE: no

The no form of this command disables this capability.

Default

advertise-router-capability

area-range
Syntax

area-range ip-prefix/mask [advertise | not-advertise]

no area-range ip-prefix/mask

area-range ipv6-prefix/prefix-length [advertise | not-advertise]

no area-range ipv6-prefix/prefix-length

Context

config>router>ospf>area

config>router>ospf>area>nssa

config>router>ospf3>area

config>router>ospf3>area>nssa

Description

This command creates ranges of addresses on an Area Border Router (ABR) for the purpose of route summarization or suppression. When a range is created, the range is configured to be advertised or not advertised to other areas. Multiple range commands can be used to summarize or hide different ranges. In the case of overlapping ranges, the most specific range command applies.

ABRs send summary link advertisements to describe routes to other areas. To minimize the number of advertisements that are flooded, you can summarize a range of IP addresses and send reachability information about these addresses in an LSA.

The ip-prefix/mask parameter applies in the ospf context. The ipv6-prefix/prefix-length parameter applies in the ospf3 context.

The no form of the command deletes the range advertisement or non-advertisement.

Default

no area-range – no range of addresses is defined

Special cases
NSSA context

in the NSSA context, the option specifies that the range applies to external routes (via type 7 LSAs) learned within the NSSA when the routes are advertised to other areas as type 5 LSAs

Area context

if this command is not entered under the NSSA context, the range applies to summary LSAs even if the area is an NSSA

Parameters
ip-prefix/mask

the IPv4 prefix for the range in dotted-decimal notation and the subnet mask for the range, expressed as a decimal integer

ipv6-prefix/prefix-length

the IPv6 prefix for the range in hexadecimal notation

advertise | not-advertise

specifies whether to advertise the summarized range of addresses to other areas

Default

advertise

blackhole-aggregate
Syntax

[no] blackhole-aggregate

Context

config>router>ospf>area

config>router>ospf3>area

Description

This command installs a low-priority blackhole route for the entire aggregate. Existing routes that make up the aggregate will have a higher priority and only the components of the range for which no route exists will be blackholed.

When performing area aggregation, addresses may be included in the range for which no actual route exists. This can cause routing loops. To avoid this problem, configure the blackhole aggregate option.

The no form of this command removes this option.

Default

blackhole-aggregate

key-rollover-interval
Syntax

key-rollover-interval seconds

no key-rollover-interval

Context

config>router>ospf3>area

Description

This command configures the key rollover interval. The no form of the command resets the configured interval to the default setting.

Default

10

Parameters
key-rollover-interval

specifies the time, in seconds, after which a key rollover will start

Values

10 to 300

loopfree-alternate-exclude
Syntax

[no] loopfree-alternate-exclude

Context

config>router>ospf>area

config>router>ospf3>area

config>router>ospf>area>interface

config>router>ospf3>area>interface

Description

This command instructs OSPF to exclude a specific interface or all interfaces participating in a specific OSPF area from the LFA SPF calculation. The LFA SPF calculation can therefore be run only where it is needed.

If an interface is excluded from the LFA SPF calculation, it is excluded in all areas. However, this command can only be executed under the area in which the specified interface is primary. When the command is executed, the interface is excluded in that area and in all other areas where the interface is secondary. If the user attempts to execute the command under an area where the interface is secondary, the command will fail.

Default

no loopfree-alternate-exclude

nssa
Syntax

[no] nssa

Context

config>router>ospf>area

config>router>ospf3>area

Description

This command enables the context to configure an OSPF Not So Stubby Area (NSSA) and adds or removes the NSSA designation from the area.

NSSAs are similar to stub areas in that no external routes are imported into the area from other OSPF areas. The major difference between a stub area and an NSSA is that an NSSA has the capability to flood external routes that it learns throughout its area and via an ABR to the entire OSPF domain.

Existing virtual links of a stub area or NSSA are removed when the designation is changed to NSSA or stub.

An area can be designated as stub or NSSA but never both at the same time.

By default, an area is not configured as an NSSA area.

The no form of the command removes the NSSA designation and configuration context from the area.

Default

no nssa

originate-default-route
Syntax

originate-default-route [type-7] [no-adjacency-check]

originate-default-route [type-nssa] [no-adjacency-check]

no originate-default-route

Context

config>router>ospf>area>nssa

config>router>ospf3>area>nssa

Description

This command enables the generation of a default route and its LSA type into an NSSA by an NSSA ABR or ASBR.

The functionality of the type-7 parameter and the type-nssa parameter is the same. The type-7 parameter is available in the ospf context; the type-nssa parameter is available in the ospf3 context. Include the type-7 or type-nssa parameter to inject a type 7 LSA default route instead of the type 3 LSA into the NSSA configured with no summaries.

To revert to a type 3 LSA, enter the originate-default-route command without the type-7 or type-nssa parameter.

When configuring an NSSA with no summaries, the ABR will inject a type 3 LSA default route into the NSSA area. Some older implementations expect a type 7 LSA default route.

The no form of the command disables origination of a default route.

Default

no originate-default-route

Parameters
type-7 | type-nssa

specifies that a type 7 LSA should be used for the default route

no-adjacency-check

specifies whether adjacency checks are performed before originating a default route. If this parameter is configured, no area 0 adjacency is required for the ABR to advertise the default route.

redistribute-external
Syntax

[no] redistribute-external

Context

config>router>ospf>area>nssa

config>router>ospf3>area>nssa

Description

This command enables the redistribution of external routes into the Not So Stubby Area (NSSA) on an NSSA area border router (ABR) that is exporting the routes into non-NSSA areas.

NSSAs are similar to stub areas in that no external routes are imported into the area from other OSPF areas. The major difference between a stub area and an NSSA is that the NSSA has the capability to flood external routes that it learns (providing it is an ASBR) throughout its area and via an ABR to the entire OSPF domain.

The no form of the command disables the default behavior to automatically redistribute external routes into the NSSA area from the NSSA ABR.

Default

redistribute-external

summaries
Syntax

[no] summaries

Context

config>router>ospf>area>nssa

config>router>ospf>area>stub

config>router>ospf3>area>nssa

config>router>ospf3>area>stub

Description

This command enables sending summary (type 3) advertisements into a stub area or NSSA on an ABR.

This parameter is particularly useful to reduce the size of the routing and link-state database (LSDB) tables within the stub or NSSA area.

By default, summary route advertisements are sent into the stub area or NSSA.

The no form of the command disables sending summary route advertisements and, for stub areas, only the default route is advertised by the ABR.

Default

summaries

stub
Syntax

[no] stub

Context

config>router>ospf>area

config>router>ospf3>area

Description

This command enables access to the context to configure an OSPF stub area and adds or removes the stub designation from the area.

External routing information is not flooded into stub areas. All routers in the stub area must be configured with the stub command.

Existing virtual links of a stub area or NSSA are removed when its designation is changed to NSSA or stub.

An OSPF area cannot be both an NSSA and a stub area at the same time.

By default, an area is not a stub area.

The no form of the command removes the stub designation and configuration context from the area.

Default

no stub

default-metric
Syntax

default-metric metric

no default-metric

Context

config>router>ospf>area>stub

config>router>ospf3>area>stub

Description

This command configures the metric used by the ABR for the default route into a stub area.

The default metric should only be configured on an ABR of a stub area.

An ABR generates a default route if the area is a stub area.

The no form of the command reverts to the default value.

Default

default-metric 1

Parameters
metric

the metric, expressed as a decimal integer, for the default route cost to be advertised into the stub area

Values

  1 to 65535

Interface/virtual link commands
interface
Syntax

interface ip-int-name [secondary]

no interface ip-int-name

Context

config>router>ospf>area

config>router>ospf3>area

Description

This command creates a context to configure an OSPF interface.

By default, interfaces are not activated in any interior gateway protocol, such as OSPF, unless explicitly configured.

The no form of the command deletes the OSPF interface configuration for this interface. The shutdown command in the config>router>ospf>area>interface context can be used to disable an interface without removing the configuration for the interface.

Default

no interface

Parameters
ip-int-name

the IP interface name. Interface names must be unique within the group of defined IP interfaces for the config>router>interface command. An interface name cannot be in the form of an IP address. Interface names can be any string up to 32 characters long composed of printable, 7-bit ASCII characters. If the string contains special characters (such as #, $, or spaces), the entire string must be enclosed within double quotes.

If the IP interface exists in a different area, the configuration will be rejected with an error message unless the keyword secondary is specified.

secondary

enables multiple secondary adjacencies to be established over this IP interface

adjacency-sid
Syntax

adjacency-sid label value

no adjacency-sid

Context

config>router>ospf>area>interface

Description

This command assigns a static value to an adjacency SID in OSPF segment routing.

The no form of the command removes the adjacency SID.

Default

no adjacency-sid

Parameters
value

the static value of the adjacency SID

Values

1 to 1048575, within the segment routing local block (SRLB) range

advertise-subnet
Syntax

[no] advertise-subnet

Context

config>router>ospf>area>interface

Description

This command enables advertising point-to-point interfaces as subnet routes (network number and mask). When disabled, point-to-point interfaces are advertised as host routes.

The no form of the command disables advertising point-to-point interfaces as subnet routes, meaning they are advertised as host routes.

Default

advertise-subnet

auth-keychain
Syntax

auth-keychain name

no auth-keychain

Context

config>router>ospf>area>interface

config>router>ospf>area>virtual-link

Description

This command associates an authentication key chain with the OSPF interface or virtual link. The keychain is a collection of keys used to authenticate OSPF messages from remote peers. The key chain allows the rollover of authentication keys during the lifetime of a session and also supports stronger authentication algorithms than clear text and MD5.

The key chain must already be defined in the config>system>security>keychain context.

Either the authentication-key command or the auth-keychain command can be used by OSPF, but both cannot be supported at the same time. If both commands are configured, the auth-keychain configuration will be applied and the authentication-key command will be ignored.

By default, authentication is not enabled.

Default

no auth-keychain

Parameters
name

the name of an existing key chain, up to 32 characters

authentication
Syntax

authentication bidirectional sa-name

authentication inbound sa-name outbound sa-name

no authentication

Context

config>router>ospf3>area>interface

config>router>ospf3>area>virtual-link

Description

This command configures an interface with a static security association (SA) used to authenticate OSPFv3 packets.

The no form of the command removes the SA name from the configuration.

Parameters
bidirectional sa-name

specifies the IPSec SA name used for transmitting and receiving OSPFv3 packets

inbound sa-name

specifies the IPSec SA name used for receiving OSPFv3 packets

outbound sa-name

specifies the IPSec SA name used for transmitting OSPFv3 packets

authentication-key
Syntax

authentication-key {authentication-key | hash-key} [hash | hash2]

no authentication-key

Context

config>router>ospf>area>interface

config>router>ospf>area>virtual-link

Description

This command configures the password used by the OSPF interface or virtual link to send and receive OSPF protocol packets on the interface when simple password authentication is configured.

All neighboring routers must use the same type of authentication and password for correct protocol communication. If the authentication-type is configured as password, the authentication key must be configured.

Either the authentication-key command or the auth-keychain command can be used by OSPF, but both cannot be supported at the same time. If both commands are configured, the auth-keychain configuration will be applied and the authentication-key command will be ignored.

By default, no authentication key is configured.

The no form of the command removes the authentication key.

Default

no authentication-key

Parameters
authentication-key

the authentication key can be any combination of ASCII characters up to 8 characters in length (unencrypted). If spaces are used in the string, enclose the entire string in quotation marks (‟ ”).

hash-key

the hash key can be any combination of ASCII characters up to 22 characters in length (encrypted) or 121 characters in length (if the hash2 parameter is used). If spaces are used in the string, enclose the entire string in quotation marks (‟ ”).

This is useful when a user must configure the parameter, but, for security purposes, the actual unencrypted key value is not provided.

hash

specifies that the key is entered in an encrypted form. If the hash parameter is not used, the key is assumed to be in a non-encrypted, clear text form. For security, all keys are stored in encrypted form in the configuration file with the hash parameter specified.

hash2

specifies that the key is entered in a more complex encrypted form. If the hash2 parameter is not used, the less encrypted hash form is assumed.

authentication-type
Syntax

authentication-type {password | message-digest}

no authentication-type

Context

config>router>ospf>area>interface

config>router>ospf>area>virtual-link

Description

This command enables authentication and specifies the type of authentication to be used on the OSPF interface.

Both simple password and message-digest authentication are supported.

By default, authentication is not enabled on an interface.

The no form of the command disables authentication on the interface.

Default

no authentication-type

Parameters
password

enables simple password (plaintext) authentication. If authentication is enabled and no authentication type is specified in the command, simple password authentication is enabled.

message-digest

enables message digest MD5 authentication in accordance with RFC 1321. If this option is configured, at least one message-digest-key must be configured.

bfd-enable
Syntax

bfd-enable [remain-down-on-failure]

no bfd-enable

Context

config>router>ospf>area>interface

config>router>ospf3>area>interface

Description

This command enables the use of bidirectional forwarding (BFD) to control the state of the associated OSPF interface. By enabling BFD on an OSPF interface, the state of the interface is tied to the state of the BFD session between the local node and the remote node. The parameters used for BFD are set via the bfd command under the IP interface.

If the BFD session does not come back up within 10 s and the remain-down-on-failure parameter is enabled, OSPF will bring down the adjacency and wait for BFD to come up again. This behavior may cause OSPF neighbors to flap because OSPF will form the adjacency and then bring it down if the BFD session is still down. If this parameter is not configured, the OSPF adjacency will form even if the BFD session does not come back up after a failure.

The no form of this command removes BFD from the associated OSPF adjacency.

Default

no bfd-enable

Parameters
remain-down-on-failure

forces adjacency down on BFD failure

dead-interval
Syntax

dead-interval seconds

no dead-interval

Context

config>router>ospf>area>interface

config>router>ospf>area>virtual-link

config>router>ospf3>area>interface

config>router>ospf3>area>virtual-link

Description

This command configures the time, in seconds, that OSPF waits before declaring a neighbor router down. If no Hello packets are received from a neighbor for the duration of the dead interval, the router is assumed to be down. The minimum interval must be two times the hello interval.

The no form of the command reverts to the default value.

Default

40

Special cases
OSPF interface

if the dead-interval configured applies to an interface, all nodes on the subnet must have the same dead interval

Virtual link

if the dead-interval configured applies to a virtual link, the interval on both termination points of the virtual link must have the same dead interval

Parameters
seconds

the dead interval in seconds, expressed as a decimal integer

Values

1 to 65535

hello-interval
Syntax

hello-interval seconds

no hello-interval

Context

config>router>ospf>area>interface

config>router>ospf>area>virtual-link

config>router>ospf3>area>interface

config>router>ospf3>area>virtual-link

Description

This command configures the interval between OSPF hellos issued on the interface or virtual link.

The hello interval, in combination with the dead interval, is used to establish and maintain the adjacency. Use this parameter to edit the frequency that Hello packets are sent.

Reducing the interval, in combination with an appropriate reduction in the associated dead-interval allows for faster detection of link and/or router failures but results in higher processing costs.

The no form of this command reverts to the default value.

Default

10

Special cases
OSPF interface

if the hello-interval configured applies to an interface, all nodes on the subnet must have the same hello interval

Virtual link

if the hello-interval configured applies to a virtual link, the interval on both termination points of the virtual link must have the same hello interval

Parameters
seconds

the hello interval in seconds, expressed as a decimal integer

Values

1 to 65535

interface-type
Syntax

interface-type {broadcast | point-to-point}

no interface-type

Context

config>router>ospf>area>interface

config>router>ospf3>area>interface

Description

This command configures the interface type to be either broadcast or point-to-point.

Use this command to set the interface type of an Ethernet link to point-to-point to avoid having to carry the broadcast adjacency maintenance overhead of the link, provided that the link is used as a point-to-point link.

If the interface type is not known when the interface is added to OSPF, and the IP interface is subsequently bound (or moved) to a different interface type, this command must be entered manually.

The no form of the command reverts to the default value.

Default

broadcast – if the physical interface is Ethernet or unknown

point-to-point – if the physical interface is T1, E1, or SONET/SDH

Special cases
Virtual link

a virtual link is always regarded as a point-to-point interface and is not configurable

Parameters
broadcast

configures the interface to maintain this link as a broadcast network. To significantly improve adjacency forming and network convergence, a network should be configured as point-to-point if only two routers are connected, even if the network is a broadcast media such as Ethernet.

point-to-point

configures the interface to maintain this link as a point-to-point link

lfa-policy-map
Syntax

lfa-policy-map route-nh-template template-name

no lfa-policy-map

Context

config>router>ospf>area>interface

config>router>ospf3>area>interface

Description

This command applies a route next hop policy template to an OSPF interface.

When a route next hop policy template is applied to an interface, it is applied in all areas. However, this command can only be executed under the area in which the specified interface is primary. When the command is executed, the template is applied in that area and in all other areas where the interface is secondary. If the user attempts to execute the command under an area where the interface is secondary, the command will fail.

If the interface has been excluded from LFA with the loopfree-alternate-exclude command, the LFA policy has no effect on the interface.

If the route next hop policy template is applied to a loopback interface or to the system interface, the command will not be rejected, but the policy will have no effect on the interface.

The no form of the command deletes the mapping of a route next hop policy template to an OSPF interface.

Default

no lfa-policy-map

Parameters
template-name

the name of an existing template

message-digest-key
Syntax

message-digest-key key-id md5 {key | hash-key} [hash | hash2]

no message-digest-key key-id

Context

config>router>ospf>area>interface

config>router>ospf>area>virtual-link

Description

This command configures a message digest key when MD5 authentication is enabled on the interface. Multiple message digest keys can be configured.

The no form of the command removes the message digest key identified by the key-id.

Default

no message-digest-key

Parameters
key-id

the key-id is expressed as a decimal integer

Values

1 to 255

key

the MD5 key, any alphanumeric string up to 16 characters in length

hash-key

the MD5 hash key, any combination of ASCII characters up to 33 characters in length (encrypted) or 132 characters in length (if the hash2 parameter is used). If spaces are used in the string, enclose the entire string in quotation marks (‟ ”).

This is useful when a user must configure the parameter, but, for security purposes, the actual unencrypted key value is not provided.

hash

specifies that the key is entered in an encrypted form. If the hash parameter is not used, the key is assumed to be in a unencrypted, clear text form. For security, all keys are stored in encrypted form in the configuration file with the hash parameter specified.

hash2

specifies that the key is entered in a more complex encrypted form. If the hash2 parameter is not used, the less encrypted hash form is assumed.

metric
Syntax

metric metric

no metric

Context

config>router>ospf>area>interface

config>router>ospf3>area>interface

Description

This command configures an explicit route cost metric for the OSPF interface that overrides the metrics calculated based on the speed of the underlying link.

The no form of the command deletes the manually configured interface metric, so the interface uses the computed metric based on the reference-bandwidth command setting and the speed of the underlying link.

Default

no metric

Parameters
metric

the metric to be applied to the interface, expressed as a decimal integer

Values

1 to 65535

mtu
Syntax

mtu bytes

no mtu

Context

config>router>ospf>area>interface

config>router>ospf3>area>interface

Description

This command configures the OSPF or OSPFv3 interface MTU value used when negotiating an OSPF or OSPFv3 adjacency.

The operational OSPF MTU value is calculated as follows.

If this command is not configured:

  • the OSPF or OSPFv3 interface operational MTU derives the MTU value from the IP interface MTU (which is derived from the port MTU); for example, port MTU minus 14 bytes for a null-encapsulated Ethernet port

    • for OSPF (not OSPFv3), if the derived MTU value is less than 576 bytes, the OSPF interface operational MTU is set to 576 bytes. If a lower interface MTU is required, you must explicitly configure it using this command.

If this command is configured:

  • for OSPF (not OSPFv3):

    • if the OSPF interface MTU is less than 576 bytes, it becomes the operational OSPF MTU, regardless of the port MTU value

    • if the OSPF interface MTU is equal to or greater than 576 bytes, and the derived interface MTU is less than 576 bytes, the operational OSPF MTU is set to 576 bytes

    • if the OSPF interface MTU is equal to or greater than 576 bytes, and the derived interface MTU is greater than 576 bytes, the operational OSPF MTU is set to the lesser of the values configured with this command and the derived MTU

    The port MTU must be set to 512 bytes or higher, since OSPF cannot support port MTU values lower than 512 bytes.

  • for OSPFv3:

    • the operational OSPF MTU is set to the lesser of the values configured with this command and the derived MTU

    • this applies only when the port MTU is set to 1280 bytes or higher, since OSPFv3 cannot support port MTU values less than 1280 bytes

To determine the actual packet size, add 14 bytes for an Ethernet packet and 18 bytes for a tagged Ethernet packet to the size of the OSPF (IP) packet MTU configured with this command.

If the OSPF mtu command is configured to a value less than the interface or port MTU value, then the OSPF MTU value will be used to transmit OSPF packets.

Use the no form of this command to revert to the default.

Default

no mtu – uses the value derived from the port MTU

Parameters
bytes

the MTU to be used by OSPF or OSPFv3 for this logical interface in bytes

Values

OSPF: 512 to 9710 (9724 – 14) (depends on the physical media)

OSPFv3: 1280 to 9710 (9724 – 14) (depends on the physical media)

node-sid
Syntax

node-sid index index-value

node-sid label label-value

no node-sid

Context

config>router>ospf>area>interface

Description

This command assigns a node SID index or label value to the prefix representing the primary address of an IPv4 network interface of type loopback. Only a single node SID can be assigned to an interface. The secondary address of an IPv4 interface cannot be assigned a node SID index and does not inherit the SID of the primary IPv4 address.

This command fails if the network interface is not of type loopback or if the interface is defined in an IES or a VPRN context.

Assigning the same SID index or label value to the same interface in two different IGP instances is not allowed within the same node.

The value of the label or index SID is taken from the range configured for this IGP instance. When using the global mode of operation, the segment routing module checks that the same index or label value cannot be assigned to more than one loopback interface address. When using the per-instance mode of operation, this check is not required because the index, and therefore the label ranges, of IGP instances are not allowed to overlap.

Parameters
index-value

specifies the node SID index value

Values

0 to 4294967295

label-value

specifies the node SID label value

Values

0 to 4294967295

passive
Syntax

[no] passive

Context

config>router>ospf>area>interface

config>router>ospf3>area>interface

Description

This command adds the passive property to the OSPF interface where passive interfaces are advertised as OSPF interfaces but do not run the OSPF protocol.

By default, only interface addresses that are configured for OSPF will be advertised as OSPF interfaces. The passive parameter allows an interface to be advertised as an OSPF interface without running the OSPF protocol. While in passive mode, the interface will ignore ingress OSPF protocol packets and not transmit any OSPF protocol packets.

The no form of the command removes the passive property from the OSPF interface.

Default

no passive

priority
Syntax

priority number

no priority

Context

config>router>ospf>area>interface

config>router>ospf3>area>interface

Description

This command configures the priority of the OSPF interface that is used in an election of the designated router on the subnet.

This parameter is only used if the interface is of type broadcast. The router with the highest-priority interface becomes the designated router. A router with priority 0 is not eligible to be a designated router or backup designated router.

The no form of the command resets the interface priority to the default value.

Default

1

Parameters
number

the interface priority expressed as a decimal integer

Values

0 to 255

retransmit-interval
Syntax

retransmit-interval seconds

no retransmit-interval

Context

config>router>ospf>area>interface

config>router>ospf>area>virtual-link

config>router>ospf3>area>interface

Description

This command specifies the length of time, in seconds, that OSPF will wait before retransmitting an unacknowledged link-state advertisement (LSA) to an OSPF neighbor.

The value should be longer than the expected round-trip delay between any two routers on the attached network. If the retransmit interval expires and no acknowledgment has been received, the LSA will be retransmitted.

The no form of this command reverts to the default interval.

Default

5

Parameters
seconds

the retransmit interval in seconds, expressed as a decimal integer

Values

1 to 1800

sid-protection
Syntax

[no] sid-protection

Context

config>router>ospf>area>interface

Description

This command enables or disables adjacency SID protection by LFA and remote LFA.

LFA and remote LFA Fast-Reroute (FRR) protection is enabled for all node SIDs and local adjacency SIDs when the user enables the loopfree-alternate option in IS-IS or OSPF at the LER and LSR. However, there may be applications where the user never wants traffic to divert from the strict hop computed by CSPF for an SR-TE LSP. In this case, the user can disable protection for all adjacency SIDs formed over a particular network IP interface using this command.

The protection state of an adjacency SID is advertised in the B-flag of the IS-IS or OSPF Adjacency SID sub-TLV.

Default

sid-protection

transit-delay
Syntax

transit-delay seconds

no transit-delay

Context

config>router>ospf>area>interface

config>router>ospf>area>virtual-link

config>router>ospf3>area>interface

config>router>ospf3>area>virtual-link

Description

This command configures the estimated time, in seconds, that it takes to transmit a link-state advertisement (LSA) on the interface or virtual link.

The no form of this command reverts to the default delay time.

Default

1

Parameters
seconds

the transit delay in seconds, expressed as a decimal integer

Values

1 to 1800

virtual-link
Syntax

[no] virtual-link router-id transit-area area-id

Context

config>router>ospf>area

config>router>ospf3>area

Description

This command configures a virtual link to connect ABRs to the backbone.

The backbone area (area 0.0.0.0) must be contiguous and all other areas must be connected to the backbone area. If it is not practical or possible to connect an area to the backbone, the ABRs must be connected via a virtual link. The two ABRs form a point-to-point-like adjacency across the transit area. A virtual link can only be configured while in the area 0.0.0.0 context.

The router-id specified in this command must be associated with the virtual neighbor. The transit area cannot be a stub area or an NSSA.

The no form of the command deletes the virtual link.

Default

no virtual-link

Parameters
router-id

the router ID of the virtual neighbor in IP address dotted-decimal notation

area-id

 the area ID specified identifies the transit area that links the backbone area to the area that has no physical connection with the backbone, expressed in dotted-decimal notation or as a 32-bit decimal integer

Values

0.0.0.0 to 255.255.255.255 (dotted-decimal) 0 to 4294967295 (decimal integer)

Show commands

Note: The following command outputs are examples only; actual displays may differ depending on supported functionality and user configuration.
router
Syntax

router [router-instance]

router service-name service-name

Context

show

Description

The command displays router instance information.

Note: Using a service-id or a service-name for this command applies only to VPRN service.
Parameters
router-instance

specifies either the router name or service ID

Values

router-name:       Base, management

service-id:           1 to 2147483647

Default

Base

service-name

specifies the service name, 64 characters maximum

ospf
Syntax

ospf [all]

Context

show>router

Description

This command enables the context to display OSPF information.

Parameters
all

shows all configured OSPF instances

ospf3
Syntax

ospf3 [all]

Context

show>router

Description

This command enables the context to display OSPFv3 information.

Parameters
all

shows all configured OSPF3 instances

area
Syntax

area [area-id] [detail] [lfa]

Context

show>router>ospf

show>router>ospf3

Description

This command displays configuration information for all areas or the specified area. When detail is specified, operational and statistical information will be displayed.

Parameters
area-id

the OSPF area ID expressed in dotted-decimal notation or as a 32-bit decimal integer

detail

displays detailed information for the area

lfa

displays LFA next hop information

Output

The following outputs are examples of OSPF area information:

Output example 
*A:Sar18 Dut-B>show>router>ospf# area detail
===============================================================================
Rtr Base OSPFv2 Instance 0 Areas (detail)
===============================================================================
-------------------------------------------------------------------------------
Area Id: 0.0.0.1
-------------------------------------------------------------------------------
Area Id          : 0.0.0.1              Type             : Standard
LFA              : Include
Virtual Links    : 0                    Total Nbrs       : 0
Active IFs       : 0                    Total IFs        : 2
Area Bdr Rtrs    : 0                    AS Bdr Rtrs      : 0
SPF Runs         : 0                    Last SPF Run     : Never
Router LSAs      : 0                    Network LSAs     : 0
Summary LSAs     : 0                    Asbr-summ LSAs   : 0
Nssa ext LSAs    : 0                    Area opaque LSAs : 0
Total LSAs       : 0                    LSA Cksum Sum    : 0x0
Blackhole Range  : True                 Unknown LSAs     : 0
Export database  : False
Export Policies  : None
Export Fltrd LSAs: 0
Import Policies  : None
Import Fltrd LSAs: 0
===============================================================================
*A:Sar18 Dut-B>show>router>ospf#
Table 7. Area field descriptions

Label

Description

Area Id

A 32-bit integer uniquely identifying an area

Type

NSSA: this area is configured as an NSSA area

Standard: this area is configured as a standard area (not NSSA or stub)

Stub: this area is configured as a stub area

LFA

Indicates whether interfaces in this area are included in the LFA SPF calculation

Virtual Links

The number of virtual links configured through this transit area

Total Nbrs

The total number of neighbors in this area

Active IFs

The active number of interfaces configured in this area

Total IFs

The total number of interfaces configured in this area

Area Bdr Rtrs

The total number of ABRs reachable within this area

AS Bdr Rtrs

The total number of ASBRs reachable within this area

SPF Runs

The number of times that the intra-area route table has been calculated using this area’s link-state database

Last SPF Run

The time that the last intra-area SPF was run on this area

Router LSAs

The total number of router LSAs in this area

Network LSAs

The total number of network LSAs in this area

Summary LSAs

The summary of LSAs in this area

Asbr-summ LSAs

The summary of ASBR LSAs in this area

Nssa-ext LSAs

The total number of NSSA-EXT LSAs in this area

Area opaque LSAs

The total number of opaque LSAs in this area

Total LSAs

The sum of LSAs in this area excluding autonomous system external LSAs

LSA Cksum Sum

The 32-bit unsigned sum of the link-state database advertisements LS checksums contained in this area’s link-state database. This checksum excludes AS External LSAs (type 5).

LSA Count

The total number of link-state advertisements in this area’s link-state database, excluding AS External LSAs

Blackhole Range

False: no blackhole route is installed for aggregates configured in this area

True: a lowest-priority blackhole route is installed for aggregates configured in this area

Unknown LSAs

The total number of unknown LSAs in this area

Export database

n/a

Export Policies

n/a

Export Flitrd LSAs

n/a

Import Policies

n/a

Import Flitrd LSAs

n/a

No. of OSPF Areas

The number of areas configured on the router
Output example 
A:ALU-A# show router ospf 0 area 0.0.0.0 lfa detail
===============================================================================
Rtr Base OSPFv2 Instance 0 Path Table (detail)
===============================================================================
-------------------------------------------------------------------------------
OSPF Area : 0.0.0.0
-------------------------------------------------------------------------------
Node               : 10.20.1.1          Metric             : 10
Interface          : In-A1              Nexthop            : 10.20.1.1
LFA Interface      : In-C1              LFA Metric         : 20
LFA type           : linkProtection     LFA Nexthop        : 10.20.1.3
 
Node               : 10.20.1.3          Metric             : 10
Interface          : In-C1              Nexthop            : 10.20.1.3
LFA Interface      : In-A1              LFA Metric         : 20
LFA type           : linkProtection     LFA Nexthop        : 10.20.1.1
 
Node               : 10.20.1.4          Metric             : 10
Interface          : In-D1              Nexthop            : 10.20.1.4

Node               : 10.20.1.6          Metric             : 20
Interface          : In-D1              Nexthop            : 10.20.1.4
LFA Interface      : In-C1              LFA Metric         : 30
LFA type           : nodeProtection     LFA Nexthop        : 10.20.1.3
===============================================================================
Table 8. Area LFA field descriptions

Label

Description

Node

The IP address of the source node

Metric

The cost to the primary route next hop

Interface

The interface name of the primary next hop

Nexthop

The IP address of the primary next hop

LFA Interface

The interface name of the LFA backup next hop

LFA Metric

The cost to the LFA backup next hop

LFA type

The LFA protection type: link protection or node protection

LFA Nexthop

The IP address of the LFA backup next hop
capabilities
Syntax

capabilities [router-id]

Context

show>router>ospf

show>router>ospf3

Description

This command displays the entries in the Router Information (RI) LSAs.

Parameters
router-id

lists only the LSAs related to that router ID. If no router-id is specified, all database entries are listed.

Output

The following output is an example of OSPF capabilities information, and Router capabilities field descriptions describes the fields.

Output example 
*A:7705:Dut-A# show router ospf capabilities 
===============================================================================
Rtr Base OSPFv2 Instance 0 Capabilities
===============================================================================
scope     Router Id           Capabilities    
-------------------------------------------------------------------------------
Area      10.20.1.1           0x38000000: Stub TE P2P-VLAN 
                              SR Algorithm:
                                  Backup-constrained-SPF
                                  IGP-metric-based-SPF
                              SR Label Range: start label 20000 range 10001
Area      10.20.1.3           0x38000000: Stub TE P2P-VLAN 
                              SR Algorithm:
                                  Backup-constrained-SPF
                                  IGP-metric-based-SPF
                              SR Label Range: start label 20000 range 10001
Area      10.20.1.4           0x38000000: Stub TE P2P-VLAN 
                              SR Algorithm:
                                  Backup-constrained-SPF
                                  IGP-metric-based-SPF
                              SR Label Range: start label 20000 range 10001
Area      10.20.1.5           0x38000000: Stub TE P2P-VLAN 
                              SR Algorithm:
                                  Backup-constrained-SPF
                                  IGP-metric-based-SPF
                              SR Label Range: start label 20000 range 10001
Area      10.20.1.6           0x38000000: Stub TE P2P-VLAN 
                              SR Algorithm:
                                  Backup-constrained-SPF
                                  IGP-metric-based-SPF
                              SR Label Range: start label 20000 range 10001
Area      10.20.1.22          0x38000000: Stub TE P2P-VLAN 
                              SR Algorithm:
                                  Backup-constrained-SPF
                                  IGP-metric-based-SPF
                              SR Label Range: start label 20000 range 10001
-------------------------------------------------------------------------------
No. of LSAs: 6
===============================================================================
*A:7705:Dut-A# 
Table 9. Router capabilities field descriptions

Label

Description

Scope

The LSA type

Router ID

The OSPF area identifier

Capabilities

The link-state ID is an LSA type-specific field containing either a number to distinguish several LSAs from the same router, an interface ID, or a router ID; it identifies the piece of the routing domain being described by the advertisement
database
Syntax

database [type {router | network | summary | asbr-summary | external | nssa | all}] [area area-id] [adv-router router-id] [link-state-id] [detail] [filtered]

database [type {router | network | inter-area-pfx | inter-area-rtr | external | nssa | intra-area-pfx | rtr-info | all}] [area area-id] [adv-router router-id] [link-state-id] [detail] [filtered]

Context

show>router>ospf

show>router>ospf3

Description

This command displays information about the OSPF link-state database.

When no command line options are specified, the command displays a summary output for all database entries.

Parameters
type

specifies to filter the OSPF LSDB information based on the specified database type

router

displays only router (Type 1) LSAs in the LSDB

network

displays only network (Type 2) LSAs in the LSDB

summary

displays only summary (Type 3) LSAs in the LSDB

asbr-summary

displays only ASBR summary (Type 4) LSAs in the LSDB

external

displays only AS external (Type 5) LSAs in the LSDB. External LSAs are maintained globally and not per area. If the display of external links is requested, the area parameter, if present, is ignored.

nssa

displays only NSSA area-specific AS external (Type 7) LSAs in the LSDB

inter-area-pfx

displays inter-area prefix LSAs

inter-area-rtr

displays inter-area router LSAs

intra-area-pfx

displays intra-area prefix LSAs

rtr-info

displays router info LSAs

all

displays all LSAs in the LSDB. The all keyword is intended to be used with either the area area-id or the adv-router router-id [link-state-id] parameters.

area area-id

displays LSDB information associated with the specified OSPF area-id

Values

ip-address – a.b.c.d

area – 0 to 4294967295

adv-router router-id [link-state-id]

displays LSDB information associated with the specified advertising router. To further narrow the number of items displayed, the link-state-id can optionally be specified.

detail

displays detailed information about the LSDB entries

filtered

displays LSDB entries that were filtered by an area import or export policy

Output

The following output is an example of OSPF database information, and Database field descriptions describes the fields.

Output example 
A:ALU-A# show router ospf database
===============================================================================
Rtr Base OSPFv2 Instance 0 Link State Database (type : All)
===============================================================================
Type         Area ID    Link State Id   Adv Rtr Id      Age  Sequence   Cksum
-------------------------------------------------------------------------------
Router       0.0.0.0    10.0.0.2        10.0.0.2       1800 0x800000b6 0xf54
Router       0.0.0.0    10.0.0.5        10.0.0.5       1902 0x8000009d 0xcb7c
Router       0.0.0.0    10.0.0.8        10.0.0.8       1815 0x8000009a 0x529b
Router       0.0.0.0    10.0.0.9        10.0.0.9       1156 0x80000085 0xd00f
Router       0.0.0.0    10.0.0.10       10.0.0.10      533  0x8000009d 0x3f1f
Router       0.0.0.0    10.0.0.11       10.0.0.11      137  0x80000086 0xc58f
Router       0.0.0.0    10.0.0.12       10.0.0.12      918  0x8000009d 0x4cf3
Router       0.0.0.0    10.0.0.13       10.0.0.13      1401 0x800000a2 0x879c
Network      0.0.0.0    10.0.53.28      10.0.0.28      149  0x80000083 0xe5cd
Network      0.0.0.0    10.0.54.28      10.0.0.28      1259 0x80000083 0xdad7
Summary      0.0.0.0    10.0.0.15       10.0.0.10      378  0x80000084 0xeba1
Summary      0.0.0.0    10.0.0.15       10.0.0.12      73   0x80000084 0xdfab
Summary      0.0.0.0    10.0.0.18       10.0.0.10      1177 0x80000083 0xcfbb
Summary      0.0.0.1    10.100.25.4     10.0.0.12      208  0x80000091 0x3049
AS Summ      0.0.0.1    10.0.0.8        10.0.0.10      824  0x80000084 0x3d07
AS Summ      0.0.0.1    10.0.0.8        10.0.0.12      1183 0x80000095 0x4bdf
AS Summ      0.0.0.1    10.0.0.9        10.0.0.10      244  0x80000082 0x73cb
AS Ext       n/a        10.1.0.0        10.0.0.23      1312 0x80000083 0x45e7
AS Ext       n/a        10.2.0.0        10.0.0.23      997  0x80000082 0x45e6
AS Ext       n/a        10.20.0.0       10.0.0.23      238  0x80000081 0x2d81
...
-------------------------------------------------------------------------------
No. of LSAs: 339
===============================================================================

A:ALU-A#  show router ospf database detail
===============================================================================
Rtr Base OSPFv2 Instance 0 Link State Database (type : All) (detail)
-------------------------------------------------------------------------------
Router LSA for Area 0.0.0.0
-------------------------------------------------------------------------------
Area Id          : 0.0.0.0              Adv Router Id    : 10.0.0.2
Link State Id    : 10.0.0.2             LSA Type         : Router
Sequence No      : 0x800000b7           Checksum         : 0xd55
Age              : 155                  Length           : 192
Options          : E
Flags            : None                 Link Count       : 14
Link Type (1)    : Point To Point
Nbr Rtr Id (1)   : 10.0.0.13            I/F Address (1)  : 10.0.22.2
No of TOS (1)    : 0                    Metric-0 (1)     : 25
Link Type (2)    : Stub Network
Network (2)      : 10.0.22.0            Mask (2)         : 255.255.255.0
No of TOS (2)    : 0                    Metric-0 (2)     : 25
Link Type (3)    : Point To Point
Nbr Rtr Id (3)   : 10.0.0.12            I/F Address (3)  : 10.0.5.2
No of TOS (3)    : 0                    Metric-0 (3)     : 25
Link Type (4)    : Stub Network
Network (4)      : 10.0.5.0            Mask (4)         : 255.255.255.0
No of TOS (4)    : 0                    Metric-0 (4)     : 25
Link Type (5)    : Point To Point 
Nbr Rtr Id (5)   : 10.0.0.8             I/F Address (5)  : 10.0.13.2
No of TOS (5)    : 0                    Metric-0 (5)     : 6
Link Type (6)    : Stub Network
Network (6)      : 10.0.13.0            Mask (6)         : 255.255.255.0
No of TOS (6)    : 0                    Metric-0 (6)     : 6
Link Type (7)    : Point To Point
Nbr Rtr Id (7)   : 10.0.0.5             I/F Address (7)  : 10.0.14.2
No of TOS (7)    : 0                    Metric-0 (7)     : 6
Link Type (8)    : Stub Network
Network (8)      : 10.0.14.0            Mask (8)         : 255.255.255.0
No of TOS (8)    : 0                    Metric-0 (8)     : 6
Link Type (9)    : Point To Point
Nbr Rtr Id (9)   : 10.0.0.11            I/F Address (9)  : 10.0.17.2
No of TOS (9)    : 0                    Metric-0 (9)     : 25
Link Type (10)   : Stub Network
Network (10)     : 10.0.17.0            Mask (10)        : 255.255.255.0
No of TOS (10)   : 0                    Metric-0 (10)    : 25
Link Type (11)   : Stub Network
Network (11)     : 10.0.0.2             Mask (11)        : 255.255.255.255
No of TOS (11)   : 0                    Metric-0 (11)    : 1
Link Type (12)   : Stub Network
Network (12)     : 10.0.18.0            Mask (12)        : 255.255.255.0
No of TOS (12)   : 0                    Metric-0 (12)    : 24
Link Type (13)   : Point To Point
Nbr Rtr Id (13)  : 10.0.0.10            I/F Address (13) : 10.0.3.2
No of TOS (13)   : 0                    Metric-0 (13)    : 25
Link Type (14)   : Stub Network
Network (14)     : 10.0.3.0             Mask (14)        : 255.255.255.0
No of TOS (14)   : 0                    Metric-0 (14)    : 25
-------------------------------------------------------------------------------

AS Ext LSA for Network 10.0.0.14
-------------------------------------------------------------------------------
Area Id          : N/A                  Adv Router Id    : 10.0.0.10
Link State Id    : 10.0.0.14            LSA Type         : AS Ext
Sequence No      : 0x80000083           Checksum         : 0xa659
Age              : 2033                 Length           : 36
Options          : E
Network Mask     : 255.255.255.255      Fwding Address   : 10.1.6.15
Metric Type      : Type 2               Metric-0         : 4
Ext Route Tag    : 0
Table 10. Database field descriptions

Label

Description

Type/ LSA Type

The LSA type

Area ID

The OSPF area identifier

Link State ID

The link-state ID is an LSA type-specific field containing either a number to distinguish several LSAs from the same router, an interface ID, or a router ID; it identifies the piece of the routing domain being described by the advertisement

Adv Rtr Id/ Adv Router Id

The router identifier of the router advertising the LSA

Age

The age of the link-state advertisement in seconds

Sequence/ Sequence No

The signed 32-bit integer sequence number

Cksum/ Checksum

The 32-bit unsigned sum of the link-state advertisements' LS checksums

No. of LSAs

The number of LSAs displayed

Options

EA: external attribute LSA support

DC: demand circuit support

R: if clear, a node can participate in OSPF topology distribution without being used to forward transit traffic

N: type 7 LSA support

MC: multicast support (not applicable)

E: external routes support

V6: not applicable

Prefix Options

P: propagate NSSA LSA

MC: multicast support (not applicable)

LA: local address capability; if set, the prefix is an IPv6 interface address of the advertising router (not applicable)

NU: no unicast capability; if set, the prefix is excluded from IPv6 unicast calculations (not applicable)

Flags

None: no flags set

V: the router is an endpoint for one or more fully adjacent virtual links having the described area as the transit area

E: the router is an AS Boundary Router

B: the router is an Area Border Router

Link Count

The number of links advertised in the LSA

Link Type (n)

The link type of the nth link in the LSA

Network (n)

The network address of the nth link in the LSA

Metric-0 (n)

The cost metric of the nth link in the LSA
interface
Syntax

interface [area area-id] [detail]

interface [ip-int-name | ip-address] [detail]

interface [ip-int-name | ip-address] database [detail]

interface [ip-int-name | ip-address | ipv6-address] [detail]

interface [ip-int-name | ip-address | ipv6-address] database [detail]

Context

show>router>ospf

show>router>ospf3

Description

This command displays the details of the OSPF interface, which can be identified by IP address or IP interface name. If neither is specified, all in-service interfaces are displayed. The ipv6-address applies only in the ospf3 context.

The area option displays all interfaces configured in the specified area.

The detail option produces a great amount of data. It is recommended that this option be used only when requesting a specific interface.

Parameters
area-id

displays all interfaces configured in this area

ip-int-name

displays only the interface identified by this interface name

ip-address

displays only the interface identified by this IP address

ipv6-address

displays only the interface identified by this IPv6 address

database

displays detailed information about the database for this interface

detail

displays detailed information for the interface

Output

The following outputs are examples of OSPF interface information:

Output example 
A:ALU-A# show router ospf interface 
===============================================================================
Rtr Base OSPFv2 Instance 0 Interface  
===============================================================================
If Name               Area Id         Designated Rtr  Bkup Desig Rtr  Adm  Oper
-------------------------------------------------------------------------------
system                0.0.0.1         10.10.10.104    0.0.0.0         Up   DR
to-103                0.0.0.20        0.0.0.0         0.0.0.0         Up   Down
-------------------------------------------------------------------------------
No. of OSPF Interfaces: 2
===============================================================================
Table 11. Interface field descriptions

Label

Description

If Name

The interface name

Area Id

A 32-bit integer uniquely identifying the area to which this interface is connected; area ID 0.0.0.0 is used for the OSPF backbone

Designated rtr

The IP interface address of the router identified as the designated router for the network in which this interface is configured

Set to 0.0.0.0 if there is no designated router

Bkup Desig Rtr

The IP interface address of the router identified as the backup designated router for the network in which this interface is configured

Set to 0.0.0.0 if there is no backup designated router

Adm

Dn: OSPF on this interface is administratively shut down

Up: OSPF on this interface is administratively enabled

Oper

Down: the initial interface state. In this state, the lower-level protocols have indicated that the interface is unusable.

Wait: the router is trying to determine the identity of the (backup) designated router for the network

PToP: the interface is operational, and connects either to a physical point-to-point network or to a virtual link

DR: this router is the designated router for this network

BDR: this router is the backup designated router for this network

ODR: the interface is operational and part of a broadcast or NBMA network on which another router has been selected to be the designated router

No. of OSPF Interfaces

The number of interfaces listed
Output example 
*A:7705:Dut-C# show router 10 ospf interface "iftoA-1" detail

===============================================================================
Rtr vprn10 OSPFv2 Instance 0 Interface "iftoA-1" (detail)
===============================================================================
-------------------------------------------------------------------------------
Configuration
-------------------------------------------------------------------------------
IP Address       : 10.1.1.3
Area Id          : 0.0.0.0              Priority         : 1
Hello Intrvl     : 1 sec                Rtr Dead Intrvl  : 4 sec
Retrans Intrvl   : 5 sec                Poll Intrvl      : 120 sec
Cfg Metric       : 1000                 Advert Subnet    : True
Transit Delay    : 1                    Cfg IF Type      : Broadcast
Passive          : False                Cfg MTU          : 1500
LSA-filter-out   : None                 Adv Rtr Capab    : Yes
LFA              : Include              LFA NH Template  : 
Load Bal Weight  : 50                    
Auth Type        : None                 
-------------------------------------------------------------------------------
State
-------------------------------------------------------------------------------
Admin Status     : Enabled              Oper State       : Backup Desig Rtr
Designated Rtr   : 1.1.1.1              Backup Desig Rtr : 3.3.3.3
IF Type          : Broadcast            Network Type     : Transit
Oper MTU         : 1500                 Last Enabled     : 03/15/2022 12:37:41
Oper Metric      : 1000                 Bfd Enabled      : No
Te Metric        : 1000                 Te State         : Down
Admin Groups     : None
Ldp Sync         : outOfService         Ldp Sync Wait    : Disabled
Ldp Timer State  : Disabled             Ldp Tm Left      : 0
-------------------------------------------------------------------------------
Statistics
-------------------------------------------------------------------------------
Nbr Count        : 1                    If Events        : 4
Tot Rx Packets   : 2158                 Tot Tx Packets   : 2155
Rx Hellos        : 2127                 Tx Hellos        : 2128
Rx DBDs          : 3                    Tx DBDs          : 2
Rx LSRs          : 1                    Tx LSRs          : 1
Rx LSUs          : 22                   Tx LSUs          : 6
Rx LS Acks       : 5                    Tx LS Acks       : 18
Retransmits      : 0                    Discards         : 0
Bad Networks     : 0                    Bad Virt Links   : 0
Bad Areas        : 0                    Bad Dest Addrs   : 0
Bad Auth Types   : 0                    Auth Failures    : 0
Bad Neighbors    : 0                    Bad Pkt Types    : 0
Bad Lengths      : 0                    Bad Hello Int.   : 0
Bad Dead Int.    : 0                    Bad Options      : 0
Bad Versions     : 0                    Bad Checksums    : 0
LSA Count        : 0                    LSA Checksum     : 0x0
===============================================================================
*A:7705:Dut-C#
Table 12. Detailed interface field descriptions

Label

Description

IP Address

The IP address and mask of this OSPF interface

Area Id

A 32-bit integer uniquely identifying the area to which this interface is connected; area ID 0.0.0.0 is used for the OSPF backbone

Priority

The priority of this interface. Used in multi-access networks, this field is used in the designated router election algorithm.

Hello Intrvl

The length of time, in seconds, between the Hello packets that the router sends on the interface. This value must be the same for all routers attached to a common network.

Rtr Dead Intrvl

The number of seconds that a router's Hello packets have not been seen before its neighbors declare the router down. This should be some multiple of the Hello interval. This value must be the same for all routers attached to a common network.

Retrans Intrvl

The number of seconds between link-state advertisement retransmissions, for adjacencies belonging to this interface. This value is also used when retransmitting database description and link-state request packets.

Poll Intrvl

The larger time interval, in seconds, between the Hello packets sent to an inactive non-broadcast multi-access neighbor

Cfg Metric

The metric to be advertised for this interface

Advert Subnet

False: when a point-to-point interface is configured as false, then the subnet is not advertised and the endpoints are advertised as host routes

True: when a point-to-point interface is configured as true, then the subnet is advertised

Transit Delay

The estimated number of seconds it takes to transmit a link-state update packet over this interface

Cfg IF Type

The configured interface type

Passive

False: this interfaces operates as a normal OSPF interface with regard to adjacency forming and network and link behavior

True: no OSPF Hellos will be sent out on this interface and the router advertises this interface as a stub network or link in its router LSAs

Cfg MTU

The desired size of the largest packet that can be sent or received on this OSPF interface, specified in octets. This size does include the underlying IP header length, but not the underlying layer headers and trailers.

LFA

Indicates whether the interface is included in the LFA SPF calculation

LSA-filter-out

Indicates whether there is filtering of outgoing OSPF LSAs

Adv Rtr Capab

Indicates whether the router advertising the LSA is configured

LFA NH Template

Indicates whether an LFA next hop policy template is applied to this interface

Load Bal Weight

Indicates the load-balancing weight value

Auth Type

Identifies the authentication procedure to be used for the packet

None: routing exchanges over the network/subnet are not authenticated

Simple: a 64-bit field is configured on a per-network basis. All packets sent on a particular network must have this configured value in their OSPF header 64-bit authentication field. This essentially serves as a ‟clear” 64-bit password.

MD5: a shared secret key is configured on all routers attached to a common network or subnet. For each OSPF protocol packet, the key is used to generate and verify a ‟message digest” that is appended to the end of the OSPF packet.

Admin Status

Disabled: OSPF on this interface is administratively shut down

Enabled: OSPF on this interface is administratively enabled

Oper State

Down: the initial interface state. In this state, the lower-level protocols have indicated that the interface is unusable.

Waiting: the router is trying to determine the identity of the (backup) designated router for the network

Point To Point: the interface is operational and connects either to a physical point-to-point network or to a virtual link

Designated Rtr: this router is the designated router for this network

Other Desig Rtr: the interface is operational and part of a broadcast or NBMA network on which another router has been selected to be the designated router

Backup Desig Rtr: this router is the backup designated router for this network

Designated Rtr

The IP interface address of the router identified as the designated router for the network in which this interface is configured

Set to 0.0.0.0 if there is no designated router

Backup Desig Rtr

The IP interface address of the router identified as the backup designated router for the network in which this interface is configured

Set to 0.0.0.0 if there is no backup designated router

IF Type

Broadcast: LANs, such as Ethernet

NBMA: X.25, Frame Relay and similar technologies

Point-To-Point: links that are definitively point-to-point

Network Type

Stub: OSPF has not established a neighbor relationship with any other OSPF router on this network; therefore, only traffic sourced or destined for this network will be routed to this network

Transit: OSPF has established at least one neighbor relationship with another OSPF router on this network; therefore, traffic en route to other networks may be routed via this network

Oper MTU

The operational size of the largest packet that can be sent or received on this OSPF interface, specified in octets. This size includes the underlying IP header length, but not the underlying layer headers and trailers.

Last Enabled

The time that this interface was last enabled to run OSPF on this interface

Oper Metric

The size of the operational metric size configured for this interface

BFD Enabled

Specifies whether BFD is enabled or disabled the for this interface

Te Metric

The TE metric configured for this interface. This metric is flooded out in the TE metric sub-TLV in the OSPF TE LSAs. Depending on the configuration, either the TE metric value or the native OSPF metric value is used in CSPF computations.

Te State

The MPLS interface TE status from OSPF standpoint

Admin Groups

The bit-map inherited from the MPLS interface that identifies the admin groups to which this interface belongs

Ldp Sync

Specifies whether the IGP-LDP synchronization feature is enabled or disabled on all interfaces participating in the OSPF routing protocol

Ldp Sync Wait

The time to wait for the LDP adjacency to come up

Ldp Timer State

The state of the LDP sync time left on the OSPF interface

Ldp Tm Left

The time left before OSPF reverts back to advertising normal metrics for this interface

Nbr Count

The number of OSPF neighbors on the network for this interface

If Events

The number of times this OSPF interface has changed its state, or an error has occurred since this interface was last enabled

Tot Rx Packets

The total number of OSPF packets received on this interface since this interface was last enabled

Tot Tx Packets

The total number of OSPF packets transmitted on this interface since this interface was last enabled

Rx Hellos

The total number of OSPF Hello packets received on this interface since this interface was last enabled

Tx Hellos

The total number of OSPF Hello packets transmitted on this interface since this interface was last enabled

Rx DBDs

The total number of OSPF database description packets received on this interface since this interface was last enabled

Tx DBDs

The total number of OSPF database description packets transmitted on this interface since this interface was last enabled

Rx LSRs

The total number of Link-State Requests (LSRs) received on this interface since this interface was last enabled

Tx LSRs

The total number of Link-State Requests (LSRs) transmitted on this interface since this interface was last enabled

Rx LSUs

The total number of Link-State Updates (LSUs) received on this interface since this interface was last enabled

Tx LSUs

The total number of Link-State Updates (LSUs) transmitted on this interface since this interface was last enabled

Rx LS Acks

The total number of Link-State Acknowledgments received on this interface since this interface was last enabled

Tx LS Acks

The total number of Link-State Acknowledgments transmitted on this interface since this interface was last enabled

Retransmits

The total number of OSPF retransmits sent on this interface since this interface was last enabled

Discards

The total number of OSPF packets discarded on this interface since this interface was last enabled

Bad Networks

The total number of OSPF packets received with invalid network or mask since this interface was last enabled

Bad Virt Links

The total number of OSPF packets received on this interface that are destined for a virtual link that does not exist since this interface was last enabled

Bad Areas

The total number of OSPF packets received with an area mismatch since this interface was last enabled

Bad Dest Addrs

The total number of OSPF packets received with the incorrect IP destination address since this interface was last enabled

Bad Auth Types

The total number of OSPF packets received with an invalid authorization type since this interface was last enabled

Auth Failures

The total number of OSPF packets received with an invalid authorization key since this interface was last enabled

Bad Neighbors

The total number of OSPF packets received where the neighbor information does not match the information this router has for the neighbor since this interface was last enabled

Bad Pkt Types

The total number of OSPF packets received with an invalid OSPF packet type since this interface was last enabled

Bad Lengths

The total number of OSPF packets received on this interface with a total length not equal to the length given in the packet itself since this interface was last enabled

Bad Hello Int.

The total number of OSPF packets received where the hello interval given in the packet was not equal to that configured on this interface since this interface was last enabled

Bad Dead Int.

The total number of OSPF packets received where the dead interval given in the packet was not equal to that configured on this interface since this interface was last enabled

Bad Options

The total number of OSPF packets received with an option that does not match those configured for this interface or area since this interface was last enabled

Bad Versions

The total number of OSPF packets received with bad OSPF version numbers since this interface was last enabled

Bad Checksums

The total number of OSPF packets received with bad checksums since this interface was last enabled

LSA Count

The total number of link-state advertisements in this area’s link-state database, excluding AS External LSAs

LSA Checksum

The 32-bit unsigned sum of the link-state database advertisements’ LS checksums contained in this area’s link-state database. This checksum excludes AS External LSAs (type 5).
lfa-coverage
Syntax

lfa-coverage

Context

show>router>ospf

show>router>ospf3

Description

This command displays OSPF LFA coverage information.

Output

The following output is an example of LFA coverage information, and LFA coverage field descriptions describes the fields.

Output example 
A:ALU-A# show router ospf lfa-coverage
===============================================================================
Rtr Base OSPFv2 Instance 0 LFA Coverage
===============================================================================
Area                     Node                       Prefix
---------------------------------------------------------------------------
0.0.0.0                  4/4(100%)                  8/8(100%)
===============================================================================
A:ALU-A#
Table 13. LFA coverage field descriptions

Label

Description

Area

The OSPF area in which LFA is enabled

Node

The number of nodes in the area on which LFA is enabled

Prefix

The number of interfaces on the nodes on which LFA is enabled
neighbor
Syntax

neighbor [ip-int-name | ip-address] [detail]

neighbor overview

neighbor [remote ip-address] [detail]

neighbor [ip-int-name] [router-id] [detail]

Context

show>router>ospf

show>router>ospf3

Description

This command displays all neighbor information or all information about neighbors of a router identified by interface name or router ID.

The detail option produces a large amount of data. It is recommended that this option be used only when requesting a specific neighbor.

Parameters
ip-int-name

displays neighbor information only for neighbors of the interface identified by the interface name

ip-address

displays neighbor information for the neighbor identified by the specified IPv4 address

detail

displays detailed information for the interface

overview

displays overview information for the interface

remote ip-address

displays information for a far-end neighbor, identified by the IP address. This parameter applies only in the ospf context.

router-id

Displays information for the neighbor identified by the router ID. This parameter only applies in the ospf3 context.

Output

The following outputs are examples of OSPF neighbor information:

Output example 
A:ALU-A# show router ospf neighbor
===============================================================================
Rtr Base OSPFv2 Instance 0 Neighbors
===============================================================================
Interface-Name                   Rtr Id          State      Pri  RetxQ   TTL
-------------------------------------------------------------------------------
pc157-2/1                        10.13.8.158     Full       1    0       37
pc157-2/2                        10.13.7.165     Full       100  0       33
pc157-2/3                        10.13.6.188     Full       1    0       38
-------------------------------------------------------------------------------
No. of Neighbors: 3
Table 14. Neighbor field descriptions

Label

Description

Interface-Name

The interface name or IP address this neighbor is using in its IP source address. On links with no address, this will not be 0.0.0.0, but the address of another of the neighbor's interfaces.

Rtr Id

A 32-bit integer uniquely identifying the neighboring router in the autonomous system

State

Down: the initial state of a neighbor conversation. It indicates that there has been no recent information received from the neighbor.

Attempt: this state is only valid for neighbors attached to NBMA networks. It indicates that no recent information has been received from the neighbor, but that a more concerted effort should be made to contact the neighbor.

Init: in this state, a Hello packet has recently been seen from the neighbor. However, bidirectional communication has not yet been established with the neighbor (that is, the router itself did not appear in the neighbor's Hello packet).

Two Way: in this state, communication between the two routers is bidirectional

ExchStart: the first step in creating an adjacency between the two neighboring routers. The goal of this step is to decide which router is the master, and to decide upon the initial database descriptor sequence number.

Exchange: in this state, the router is describing its entire link-state database by sending database description packets to the neighbor

Loading: in this state, Link-State Request packets are sent to the neighbor asking for the more recent LSAs that have been discovered (but not yet received) in the Exchange state

Full: in this state, the neighboring routers are fully adjacent. These adjacencies will now appear in router-LSAs and network-LSAs.

Pri

The priority of this neighbor in the designated router election algorithm. The value 0 signifies that the neighbor is not eligible to become the designated router on this particular network.

RetxQ

The current length of the retransmission queue

TTL

The time until this neighbor is declared down; this timer is set to the dead router interval when a valid Hello packet is received from the neighbor

No. of Neighbors

The number of adjacent OSPF neighbors on this interface
Output example 
A:ALU-A# show router ospf neighbor 10.13.8.150 detail
===============================================================================
Rtr Base OSPFv2 Instance 0 Neighbors (detail)
-------------------------------------------------------------------------------
Neighbor Rtr Id  : 10.13.8.158          Interface: pc157-2/1
-------------------------------------------------------------------------------
Neighbor IP Addr : 10.16.1.8
Local IF IP Addr : 10.16.1.7
Area Id          : 0.0.0.0
Designated Rtr   : 0.0.0.0              Backup Desig Rtr : 0.0.0.0
Neighbor State   : Full                 Priority         : 1
Retrans Q Length : 0                    Options          : -E--O-
Events           : 4                    Last Event Time  : 05/06/2015 00:11:16
Up Time          : 1d 18:20:20          Time Before Dead : 38 sec
Bad Nbr States   : 1                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
Num Restarts     : 0                    Last Restart at  : Never
-------------------------------------------------------------------------------
A:ALU-A#
Table 15. Neighbor (detail) field descriptions

Label

Description

Neighbor IP Addr

The IP address this neighbor is using in its IP source address. On links with no IP address, this will not be 0.0.0.0, but the address of another of the neighbor's interfaces.

Local IF IP Addr

The IP address of this OSPF interface

Area Id

A 32-bit integer uniquely identifying the area to which this interface is connected; area ID 0.0.0.0 is used for the OSPF backbone

Designated Rtr

The IP interface address of the router identified as the designated router for the network in which this interface is configured

Set to 0.0.0.0 if there is no designated router

Neighbor Rtr Id

A 32-bit integer uniquely identifying the neighboring router in the AS

Neighbor State

Down: the initial state of a neighbor conversation. It indicates that there has been no recent information received from the neighbor.

Attempt: this state is only valid for neighbors attached to NBMA networks. It indicates that no recent information has been received from the neighbor, but that a more concerted effort should be made to contact the neighbor.

Init: in this state, a Hello packet has recently been seen from the neighbor. However, bidirectional communication has not yet been established with the neighbor (that is, the router itself did not appear in the neighbor's Hello packet).

Two Way: in this state, communication between the two routers is bidirectional

Exchange start: the first step in creating an adjacency between the two neighboring routers. The goal of this step is to decide which router is the master, and to decide upon the initial database descriptor sequence number.

Exchange: in this state, the router is describing its entire link-state database by sending database description packets to the neighbor

Loading: in this state, Link-State Request packets are sent to the neighbor asking for the more recent LSAs that have been discovered (but not yet received) in the Exchange state

Full: in this state, the neighboring routers are fully adjacent. These adjacencies will now appear in router-LSAs and network-LSAs.

Priority

The priority of this neighbor in the designated router election algorithm. The value 0 signifies that the neighbor is not eligible to become the designated router on this particular network.

Retrans Q Length

The current length of the retransmission queue

Options

E: external routes support

MC: multicast support (not applicable)

N/P: type 7 LSA support

EA: external attribute LSA support

DC: demand circuit support

O: opaque LSA support

Backup Desig Rtr

The IP interface address of the router identified as the backup designated router for the network in which this interface is configured

Set to 0.0.0.0 if there is no backup designated router

Events

The number of times this neighbor relationship has changed state, or an error has occurred

Last Event Time

The time that the last event occurred that affected the adjacency to the neighbor

Up Time

The uninterrupted time, in hundredths of seconds, that the adjacency to this neighbor has been up. To evaluate when the last state change occurred, see last event time.

Time Before Dead

The time until this neighbor is declared down; this timer is set to the dead router interval when a valid Hello packet is received from the neighbor

Bad Nbr States

The total number of OSPF packets received when the neighbor state was not expecting to receive this packet type since this interface was last enabled

LSA Inst fails

The total number of times that an LSA could not be installed into the link-state database due to a resource allocation issue since this interface was last enabled

Bad Seq Nums

The total number of times that a database description packet was received with a sequence number mismatch since this interface was last enabled

Bad MTUs

The total number of times that the MTU in a received database description packet was larger than the MTU of the receiving interface since this interface was last enabled

Bad Packets

The total number of times that an LS update was received with an illegal LS type or an option mismatch since this interface was last enabled

LSA not in LSDB

The total number of times that an LS request was received for an LSA not installed in the LSDB of this router since this interface was last enabled

Option Mismatches

The total number of times that an LS update was received with an option mismatch since this interface was last enabled

Nbr Duplicates

The total number of times that a duplicate database description packet was received during the exchange state since this interface was last enabled
Output example 
*A:7705:Dut-A# show router ospf neighbor overview
===============================================================================
Rtr Base OSPFv2 Instance 0 Neighbor (overview)
===============================================================================
Neighbor-state                   Neighbors
-------------------------------------------------------------------------------
DOWN                             0
ATTEMPT                          0
INIT                             0
2WAY                             0
EXSTART                          0
EXCHANGE                         0
LOADING                          0
FULL                             0
-------------------------------------------------------------------------------
Total neighbors                  0
===============================================================================
*A:7705:Dut-A# show router ospf#
Table 16. Neighbor (overview) field descriptions

Label

Description

Neighbor State

Down: the initial state of a neighbor conversation. It indicates that there has been no recent information received from the neighbor.

Attempt: this state is only valid for neighbors attached to NBMA networks. It indicates that no recent information has been received from the neighbor, but that a more concerted effort should be made to contact the neighbor.

Init: in this state, a Hello packet has recently been seen from the neighbor. However, bidirectional communication has not yet been established with the neighbor (that is, the router itself did not appear in the neighbor's Hello packet).

Two Way: in this state, communication between the two routers is bidirectional

Exchange start: the first step in creating an adjacency between the two neighboring routers. The goal of this step is to decide which router is the master, and to decide upon the initial database descriptor sequence number.

Exchange: in this state, the router is describing its entire link-state database by sending database description packets to the neighbor

Loading: in this state, Link-State Request packets are sent to the neighbor asking for the more recent LSAs that have been discovered (but not yet received) in the Exchange state

Full: in this state, the neighboring routers are fully adjacent. These adjacencies will now appear in router-LSAs and network-LSAs.

Neighbors

The number of neighbors in the corresponding neighbor state

Total neighbors

The total number of neighbors
opaque-database
Syntax

opaque-database [area area-id | as] [adv-router router-id] [ls-id] [detail]

Context

show>router>ospf

Description

This command displays OSPF opaque database information.

Parameters
area area-id

displays all opaque databases configured in this area

Values

ip-address – a.b.c.d

area – 0 to 4294967295

as

displays opaque databases configured in the autonomous system (AS)

adv-router router-id [ls-id]

displays opaque database information associated with the specified advertising router. To further narrow the number of items displayed, the ls-id parameter can optionally be specified.

Output

The following output is an example of OSPF opaque database information, and OSPF opaque database field descriptions  describes the fields.

Output example 
*A:7705:Dut-A# show router ospf opaque-database 
===============================================================================
Rtr Base OSPFv2 Instance 0 Opaque Link State Database (type: All)
===============================================================================
Type  Id              Link State Id     Adv Rtr Id      Age  Sequence   Cksum
-------------------------------------------------------------------------------
Area  0.0.0.0         10.0.0.1           10.20.1.1       45   0x80000002 0xfd10
Area  0.0.0.0         10.0.0.3           10.20.1.1       648  0x80000002 0x2585
Area  0.0.0.0         10.0.0.4           10.20.1.1       603  0x80000002 0xd181
Area  0.0.0.0         10.0.0.0           10.20.1.1       242  0x80000003 0xb15d
Area  0.0.0.0         10.0.0.2           10.20.1.1       2118 0x80000002 0xb39a
Area  0.0.0.0         10.0.0.3           10.20.1.1       283  0x80000003 0x5e01
Area  0.0.0.0         10.0.0.4           10.20.1.1       579  0x80000003 0x4717
Area  0.0.0.0         10.0.0.1           10.20.1.3       2135 0x80000001 0x803
Area  0.0.0.0         10.0.0.3           10.20.1.3       425  0x80000002 0x5551
Area  0.0.0.0         10.0.0.4           10.20.1.3       449  0x80000002 0xbf7d
Area  0.0.0.0         10.0.0.0           10.20.1.3       2128 0x80000002 0xa766
Area  0.0.0.0         10.0.0.2           10.20.1.3       444  0x80000003 0xf551
Area  0.0.0.0         10.0.0.3           10.20.1.3       264  0x80000003 0x83aa
Area  0.0.0.0         10.0.0.4           10.20.1.3       246  0x80000003 0x6cdb
Area  0.0.0.0         10.0.0.5           10.20.1.3       561  0x80000003 0x1e3d
Area  0.0.0.0         10.0.0.1           10.20.1.4       354  0x80000002 0xafd
Area  0.0.0.0         10.0.0.3           10.20.1.4       602  0x80000003 0xdf5b
Area  0.0.0.0         10.0.0.4           10.20.1.4       580  0x80000003 0x45fa
Area  0.0.0.0         10.0.0.0           10.20.1.4       343  0x80000003 0x9f6c
Area  0.0.0.0         10.0.0.2           10.20.1.4       6    0x80000006 0x122f
Area  0.0.0.0         10.0.0.3           10.20.1.4       64   0x80000003 0xc750
Area  0.0.0.0         10.0.0.4           10.20.1.4       493  0x80000003 0x3d0e
Area  0.0.0.0         10.0.0.1           10.20.1.5       2106 0x80000001 0x10f6
Area  0.0.0.0         10.0.0.3           10.20.1.5       2088 0x80000001 0xe461
Area  0.0.0.0         10.0.0.4           10.20.1.5       2088 0x80000001 0x880f
Area  0.0.0.0         10.0.0.0           10.20.1.5       2100 0x80000002 0x9b70
Area  0.0.0.0         10.0.0.2           10.20.1.5       2089 0x80000002 0x3c06
Area  0.0.0.0         10.0.0.3           10.20.1.5       2085 0x80000002 0x4dd3
Area  0.0.0.0         10.0.0.4           10.20.1.5       2088 0x80000002 0x2923
Area  0.0.0.0         10.0.0.1           10.20.1.6       2106 0x80000001 0x14f0
Area  0.0.0.0         10.0.0.3           10.20.1.6       2089 0x80000001 0xaaeb
Area  0.0.0.0         10.0.0.0           10.20.1.6       2100 0x80000002 0x9575
Area  0.0.0.0         10.0.0.2           10.20.1.6       2089 0x80000002 0x5ee0
Area  0.0.0.0         10.0.0.3           10.20.1.6       2089 0x80000002 0xc455
Area  0.0.0.0         10.0.0.1           10.20.1.22      264  0x80000002 0x5291
Area  0.0.0.0         10.0.0.3           10.20.1.22      400  0x80000002 0xa889
Area  0.0.0.0         10.0.0.4           10.20.1.22      2116 0x80000001 0x73ca
Area  0.0.0.0         10.0.0.0           10.20.1.22      239  0x80000003 0x33c6
Area  0.0.0.0         10.0.0.2           10.20.1.22      362  0x80000003 0x74ad
Area  0.0.0.0         10.0.0.3           10.20.1.22      415  0x80000003 0x1eed
Area  0.0.0.0         10.0.0.4           10.20.1.22      390  0x80000003 0xe337
Area  0.0.0.0         10.0.0.5           10.20.1.22      2087 0x80000002 0x908a
-------------------------------------------------------------------------------
No. of Opaque LSAs: 42
===============================================================================

*A:7705:Dut-A# show router ospf opaque-database adv-router 10.20.1.6 
===============================================================================
Rtr Base OSPFv2 Instance 0 Opaque Link State Database (type: All)
===============================================================================
Type  Id              Link State Id     Adv Rtr Id      Age  Sequence   Cksum
-------------------------------------------------------------------------------
Area  0.0.0.0         10.0.0.1           10.20.1.6       2222 0x80000001 0x14f0
Area  0.0.0.0         10.0.0.3           10.20.1.6       2204 0x80000001 0xaaeb
Area  0.0.0.0         10.0.0.0           10.20.1.6       2216 0x80000002 0x9575
Area  0.0.0.0         10.0.0.2           10.20.1.6       2204 0x80000002 0x5ee0
Area  0.0.0.0         10.0.0.3           10.20.1.6       2203 0x80000002 0xc455
-------------------------------------------------------------------------------
No. of Opaque LSAs: 5
===============================================================================

*A:7705:Dut-A# show router ospf opaque-database adv-router 10.20.1.6 detail 
===============================================================================
Rtr Base OSPFv2 Instance 0 Opaque Link State Database (type: All) (detail)
===============================================================================
-------------------------------------------------------------------------------
Opaque LSA
-------------------------------------------------------------------------------
Area Id          : 0.0.0.0              Adv Router Id    : 10.20.1.6
Link State Id    : 10.0.0.1             LSA Type         : Area Opaque
Sequence No      : 0x80000001           Checksum         : 0x14f0
Age              : 2243                 Length           : 28
Options          :  E                   
Advertisement    : Traffic Engineering  
     ROUTER-ID TLV  (0001) Len   4 : 10.20.1.6
-------------------------------------------------------------------------------
Opaque LSA
-------------------------------------------------------------------------------
Area Id          : 0.0.0.0              Adv Router Id    : 10.20.1.6
Link State Id    : 10.0.0.3             LSA Type         : Area Opaque
Sequence No      : 0x80000001           Checksum         : 0xaaeb
Age              : 2226                 Length           : 124
Options          :  E                   
Advertisement    : Traffic Engineering  
     LINK INFO TLV  (0002) Len 100 :
       Sub-TLV: 1     Len: 1     LINK_TYPE    : 2
       Sub-TLV: 2     Len: 4     LINK_ID      : 10.10.6.6
       Sub-TLV: 3     Len: 4     LOC_IP_ADDR  : 10.10.6.6
       Sub-TLV: 4     Len: 4     REM_IP_ADDR  : 10.10.10.0
       Sub-TLV: 5     Len: 4     TE_METRIC    : 100
       Sub-TLV: 6     Len: 4     MAX_BDWTH    : 10000000 Kbps
       Sub-TLV: 7     Len: 4     RSRVBL_BDWTH : 10000000 Kbps
       Sub-TLV: 8     Len: 32    UNRSRVD_CLS0 :
         P0: 10000000 Kbps P1: 10000000 Kbps P2: 10000000 Kbps P3: 10000000 Kbps 
         P4: 10000000 Kbps P5: 10000000 Kbps P6: 10000000 Kbps P7: 10000000 Kbps 
       Sub-TLV: 9     Len: 4     ADMIN_GROUP  : 0 None
-------------------------------------------------------------------------------
Opaque LSA
-------------------------------------------------------------------------------
Area Id          : 0.0.0.0              Adv Router Id    : 10.20.1.6
Link State Id    : 10.0.0.0             LSA Type         : Area Opaque
Sequence No      : 0x80000002           Checksum         : 0x9575
Age              : 2237                 Length           : 52
Options          :  E                   
Advertisement    : Router Info          
    Capabilities (1) Len 4 :
        0x38000000
    SR algorithm (8) Len 2 :
        0x2         0x0     
    SR label range (9) Len 12 :
        Range-size=10001
        Sub-TLV SID/label(1) len 3 :
            label=20000
-------------------------------------------------------------------------------
Opaque LSA
-------------------------------------------------------------------------------
Area Id          : 0.0.0.0              Adv Router Id    : 10.20.1.6
Link State Id    : 10.0.0.2             LSA Type         : Area Opaque
Sequence No      : 0x80000002           Checksum         : 0x5ee0
Age              : 2227                 Length           : 44
Options          :  E                   
Advertisement    : Extended Prefix      
    TLV Extended prefix (1) Len 20 :
        rtType=1 pfxLen=32 AF=0 pfx=10.20.1.6
            Flags=Node (0x40)
        Sub-TLV Prefix SID (2) len 8 : 
            Flags=noPHP (0x40)
            MT-ID=0 Algorithm=0 SID/Index/Label=1006
-------------------------------------------------------------------------------
Opaque LSA
-------------------------------------------------------------------------------
Area Id          : 0.0.0.0              Adv Router Id    : 10.20.1.6
Link State Id    : 10.0.0.3             LSA Type         : Area Opaque
Sequence No      : 0x80000002           Checksum         : 0xc455
Age              : 2226                 Length           : 52
Options          :  E                   
Advertisement    : Extended Link        
    TLV Extended link (1) Len 28  :
        link Type=Transit (2)  Id=10.10.6.6 Data=10.10.6.6
        Sub-TLV LAN-Adj-SID (3) len 11 :
            Flags=Value Local (0x60)
            MT-ID=0 Weight=0 Neighbor-ID=10.20.1.5
            SID/Index/Label=131071
===============================================================================
*A:7705:Dut-A#
Table 17. OSPF opaque database field descriptions 

Label

Description

Area Id

A 32-bit integer uniquely identifying an area; area ID 0.0.0.0 is used for the OSPF backbone

Type

NSSA

This area is configured as an NSSA area

Area

This area is configured as a standard area (not NSSA or stub)

Stub

This area is configured as a stub area

Link State Id

An LSA type-specific field containing either a router ID or an IP address; it identifies the piece of the routing domain being described by the advertisement

Adv Rtr Id

The router identifier of the router advertising the LSA

Age

The age of the link state advertisement in seconds

Sequence

The signed 32-bit integer sequence number

Cksum

The 32-bit unsigned sum of the link-state advertisements LS checksums
prefix-sids
Syntax

prefix-sids [ip-prefix[/prefix-length] [sid sid] [adv-router router-id]

Context

show>router>ospf

Description

This command displays OSPF prefix SIDs information.

Parameters
ip-prefix[/prefix-length]

displays information for the specified IP prefix and length, up to 64 characters

sid

displays information for the specific segment identifier

Values

0 to 524287

router-id

displays information for the specific advertising router identified by its router ID

Output

The following output is an example of OSPF prefix SIDs information, and Prefix SIDs field descriptions describes the fields.

Output example 
*A:7705:Dut-A# show router ospf prefix-sids 
========================================================================
Rtr Base OSPFv2 Instance 0 Prefix-Sids
========================================================================
Prefix                             Area            RtType      SID
                                   Adv-Rtr                     Flags
------------------------------------------------------------------------
10.20.1.1/32                       0.0.0.0         INTRA-AREA  1001
                                   10.20.1.1                   NnP
10.20.1.3/32                       0.0.0.0         INTRA-AREA  1003
                                   10.20.1.3                   NnP
10.20.1.4/32                       0.0.0.0         INTRA-AREA  1004
                                   10.20.1.4                   NnP
10.20.1.5/32                       0.0.0.0         INTRA-AREA  1005
                                   10.20.1.5                   NnP
10.20.1.6/32                       0.0.0.0         INTRA-AREA  1006
                                   10.20.1.6                   NnP
10.20.1.22/32                      0.0.0.0         INTRA-AREA  1002
                                   10.20.1.22                  NnP
------------------------------------------------------------------------
No. of Prefix/SIDs: 6
SID Flags : N = Node-SID
           nP = no penultimate hop POP
            M = Mapping server
            E = Explicit-Null
            V = Prefix-SID carries a value
            L = value/index has local significance
            I = Inter Area flag 
            A = Attached flag 
            B = Backup flag 
========================================================================

*A:7705:Dut-A# show router ospf prefix-sids sid 1002     
========================================================================
Rtr Base OSPFv2 Instance 0 Prefix-Sids
========================================================================
Prefix                             Area            RtType      SID
                                   Adv-Rtr                     Flags
------------------------------------------------------------------------
10.20.1.22/32                      0.0.0.0         INTRA-AREA  1002
                                   10.20.1.22                  NnP
------------------------------------------------------------------------
No. of Prefix/SIDs: 1
SID Flags : N = Node-SID
           nP = no penultimate hop POP
            M = Mapping server
            E = Explicit-Null
            V = Prefix-SID carries a value
            L = value/index has local significance
            I = Inter Area flag 
            A = Attached flag 
            B = Backup flag 
========================================================================
Table 18. Prefix SIDs field descriptions

Label

Description

Prefix

The IP prefix for the SID

Area

The OSPF area

Adv-Rtr

The advertised router IP address

RtType

The type of route

Active

The status of the route: active (Y) or inactive (N)

SID

The segment routing identifier (SID)

Flags

The flags related to the advertised router:

    R = Re-advertisement

    N = Node SID

    nP = No penultimate hop POP

    E = Explicit null

    V = Prefix-SID carries a value

    L = Value/index has local significance
range
Syntax

range [area-id]

Context

show>router>ospf

show>router>ospf3

Description

This command displays ranges of addresses on an ABR for the purpose of route summarization or suppression.

Parameters
area-id

displays the configured ranges for the specified area

Output

The following output is an example of OSPF range information, and Area range field descriptions describes the fields.

Output example 
A:ALU-A# show router ospf range
==========================================================
Rtr Base OSPFv2 Instance 0 Ranges
==========================================================
Area Id         Prefix       Advertise   LSDB-Type  
----------------------------------------------------------
No. of Ranges: 0                                          
==========================================================
A:ALU-A# 
Table 19. Area range field descriptions

Label

Description

Area Id

A 32-bit integer uniquely identifying an area; area ID 0.0.0.0 is used for the OSPF backbone

Prefix

The mask for the range expressed as a decimal integer mask length or in dotted-decimal notation

Advertise

False: the specified address/mask is not advertised outside the area

True: the specified address/mask is advertised outside the area

LSDB-Type

NSSA: this range was specified in the NSSA context, and specifies that the range applies to external routes (via type 7 LSAs) learned within the NSSA when the routes are advertised to other areas as type 5 LSAs

Summary: this range was not specified in the NSSA context; the range applies to summary LSAs even if the area is an NSSA
routes
Syntax

routes [ip-prefix[/prefix-length]] [type] [detail] [alternative] [summary] [exclude-shortcut]

routes [ip-prefix[/pfx-len]] [type] [detail] [alternative] [summary]

Context

show>router>ospf

show>router>ospf3

Description

This command displays information about OSPF routes.

Parameters
ip-prefix/prefix-length

displays information for the specified IP address and prefix length

ip-prefix/pfx-len

displays information for the specified IP address and prefix length. This parameter applies only in the ospf3 context.

type

displays information for the specified route type

Values

intra-area, inter-area, external-1, external-2, nssa-1, nssa-2

detail

displays detailed information for the routes

alternative

displays the level of protection per prefix

summary

displays summary information for the routes

exclude-shortcut

displays routes without shortcuts

Output

The following outputs are examples of OSPF route information.

Output example 
A:ALU-A# show router ospf routes
===============================================================================
Rtr Base OSPFv2 Instance 0 Route Table
===============================================================================
Destination          Type(Dest)    Stat     SID    SIDflgs
   NHIP             NHIF     Cost[E2]
-------------------------------------------------------------------------------
10.1.1.1/32           IA (HOST)     N (R)
   10.1.3.1          3          1000
10.1.2.0/24           IA (NET)      N (R)
   10.1.3.1          3          2000
   10.2.3.2          4          2000
10.1.3.0/24           IA (NET)      D (F)
   DIRECT           3          1000
10.2.3.0/24           IA (NET)      D (F)
   DIRECT           4          1000
10.2.4.0/24           IA (NET)      N (R)
   10.2.3.2          5          2000
10.3.5.0/24           IA (NET)      D (F)
   DIRECT           6          1000
10.4.5.0/24           IA (NET)      N (R)
   10.3.5.5          6          2000
10.4.6.0/24           IE (NET)      N (R)
   10.2.3.2          5          3000
   10.3.5.5          6          3000
10.5.6.0/24           IE (NET)      N (R)
   10.3.5.5          6          2000
10.2.2.2/32           IA (HOST)     N (R)
   10.2.3.2          5          1000
10.2.3.0/24           IA (NET)      D (F)
   DIRECT 5 1000
10.3.3.3/32           IA (HOST)     D (F)
   DIRECT           2          0
10.4.4.4/32           IA (HOST)     N (R)
   10.2.3.2          5          2000
   10.3.5.5          6          2000
10.5.5.5/32           IA (HOST)     N (R)
   1.3.5.5          6          1000
10.6.6.6/32           IE (HOST)     N (R)
   10.3.5.5          6          2000
10.20.1.1/32         IA (HOST)     N (R)    11     NnP
   10.1.3.1          3          1000
10.20.1.2/32         IA (HOST)     N (R)    22     NnP
   10.2.3.2          5          1000
10.20.1.3/32         IA (HOST)     D (F)    33     NnP
   DIRECT           1          0
10.20.1.4/32         IA (HOST)     N (R)    44     NnP
   10.2.3.2          5          2000
   10.3.5.5          6          2000
10.20.1.5/32         IA (HOST)     N (R)    55     NnP
   10.3.5.5          6          1000
10.20.1.6/32         IE (HOST)     N (R)    66     NnP
   10.3.5.5          6          2000
10.20.1.1/0          IA (RTR)      N (N)
   10.1.3.1          3          1000
10.20.1.2/0          IA (AB-AS)    N (N)
   10.2.3.2          5          1000
10.20.1.2/0          IA (AB-AS)    N (N)
   10.2.3.2          4          1000
10.20.1.4/0          IA (AB-AS)    N (N)
   10.2.3.2          5          2000
   10.3.5.5          6          2000
10.20.1.5/0          IA (AB-AS)    N (N)
   10.3.5.5          6          1000
-------------------------------------------------------------------------------
No. of routes found: 26 (31 paths)
Stat: D = direct   N = not direct
 (RTM stat):(R) = added      (F) = add failed
            (N) = not added  (D) = policy discarded
SID Flags  : N = Node-SID
            nP = no penultimate hop POP
             M = Mapping server
             E = Explicit-Null
             V = Prefix-SID carries a value
             L = value/index has local significance
             I = Inter Area flag
             A = Attached flag
===============================================================================
A:ALU-A# 

A:ALU-A# show router ospf routes alternative detail
=======================================================================
Rtr Base OSPFv2 Instance 0 Routing Table (alternative) (detail)  
=======================================================================
Destination         Type(Dest)    Stat
   NHIP            NHIF     Cost[E2]    Area            Tunnel-Information
   A-NHIP(L)       A-NHIF   A-Cost[E2]  A-Type          PGID
-----------------------------------------------------------------------
10.1.2.0/24          IA (NET)      D (F)
   DIRECT          2            10      0.0.0.0
10.1.3.0/24          IA (NET)      D (F)
   DIRECT          3            10      0.0.0.0
10.2.3.0/24          IA (NET)      N (R)
   10.1.2.2         2            20      0.0.0.0
   10.1.3.3         3            20      0.0.0.0
10.2.4.0/24          IA (NET)      N (R)
   10.1.2.2         2            20      0.0.0.0
   10.1.3.3(L)      3            30      LINK            0x130015
10.3.5.0/24          IA (NET)      N (R)
   10.1.3.3         3            20      0.0.0.0
   10.1.2.2(L)      2            30      LINK            0x130016
10.4.5.0/24          IA (NET)      N (R)
   10.1.2.2         2            30      0.0.0.0
   10.1.3.3         3            30      0.0.0.0
10.4.6.0/24          IA (NET)      N (R)
   10.1.2.2         2            30      0.0.0.0
   10.1.3.3(L)      3            40      LINK            0x130015
10.5.6.0/24          IA (NET)      N (R)
   10.1.3.3         3            30      0.0.0.0
   10.1.2.2(L)      2            40      LINK            0x130016
10.20.1.1/32        IA (HOST)     D (F)
   DIRECT          1             0      0.0.0.0
10.20.1.2/32        IA (HOST)     N (R)
   10.1.2.2         2            10      0.0.0.0
   10.1.3.3(L)      3            20      LINK            0x130015
10.20.1.3/32        IA (HOST)     N (R)
   10.1.3.3         3            10      0.0.0.0
   10.1.2.2(L)      2            20      LINK            0x130016
10.20.1.4/32        IA (HOST)     N (R)
   10.1.2.2         2            20      0.0.0.0
   10.1.3.3(L)      3            30      LINK            0x130015
10.20.1.5/32        IA (HOST)     N (R)
   1.1.3.3         3            20      0.0.0.0
   1.1.2.2(L)      2            30      LINK            0x130016
10.20.1.6/32        IA (HOST)     N (R)
   10.1.3.3         3            30      0.0.0.0
   10.1.2.2         2            30      0.0.0.0
10.20.1.2/0         IA (RTR)      N (N)
   10.1.2.2         2            10      0.0.0.0
10.20.1.3/0         IA (RTR)      N (N)
   10.1.3.3         3            10      0.0.0.0
10.20.1.4/0         IA (RTR)      N (N)
   10.1.2.2         2            20      0.0.0.0
10.20.1.5/0         IA (RTR)      N (N)
   10.1.3.3         3            20      0.0.0.0
10.20.1.6/0         IA (RTR)      N (N)
   10.1.3.3         3            30      0.0.0.0
   10.1.2.2         2            30      0.0.0.0
-----------------------------------------------------------------------
19 OSPFv2 routes found (23 paths)
Flags: L = Loop-Free Alternate nexthop
Stat: D = direct   N = not direct
 (RTM stat):(R) = added      (F) = add failed
            (N) = not added  (D) = policy discarded
=======================================================================
A:ALU-A# 
sham-link
Syntax

sham-link [interface-name] [detail]

sham-link interface-name remote ip-address [detail]

Context

show>router>ospf

Description

This command displays OSPF sham-link information.

Parameters
interface-name

displays only the sham-link information for the specified interface name, up to 32 characters

ip-address

displays only the sham-link information for the specified remote neighbor IP address, in the format a.b.c.d

detail

displays detailed OSPF sham-link information

Output

The following outputs are examples of OSPF sham-link information:

Output example 
*A:7705:Dut-C# show router 1000 ospf sham-link 
===============================================================================
Rtr vprn1000 OSPFv2 Instance 0 Sham-Links
===============================================================================
If Name                          Nbr IP                        Metric Adm  Oper
-------------------------------------------------------------------------------
myLocalShamItf                   50.0.0.2                      1      Up   PToP
-------------------------------------------------------------------------------
No. of OSPF Sham-links: 1
===============================================================================
*A:7705:Dut-C# 
Table 20. OSPF sham link field descriptions (standard)

Label

Description

If Name

The interface name

Nbr IP

The remote neighbor IP address

Metric

The route cost metric for the sham link

Adm

Dn: OSPF on this sham link is administratively shut down

Up: OSPF on this sham link is administratively enabled

Oper

Down: the initial interface state. In this state, the lower-level protocols have indicated that the interface is unusable.

Wait: the router is trying to determine the identity of the (backup) designated router for the network

PToP: the interface is operational and connects either to a physical point-to-point network, a virtual link, or sham link

DR: this router is the designated router for this network

BDR: this router is the backup designated router for this network

ODR: the interface is operational and part of a broadcast or NBMA network on which another router has been selected to be the designated router

No. of OSPF Sham-links

The total number of listed sham links
Output example 
*A:7705:Dut-C# show router 1000 ospf sham-link detail 
===============================================================================
Rtr vprn1000 OSPFv2 Instance 0 Sham-Links (detail)
===============================================================================
-------------------------------------------------------------------------------
Interface: myLocalShamItf Remote Nbr: 50.0.0.2
-------------------------------------------------------------------------------
Local IP Address : 50.0.0.1
Area Id          : 0.0.0.0              Last Enabled     : 02/24/2021 17:48:22
Admin Status     : Enabled              Oper State       : Point To Point
Transit Delay    : 1 sec                Retrans Intrvl   : 5 sec
Hello Intrvl     : 10 sec               Rtr Dead Intrvl  : 40 sec
Cfg Metric       : 1                    Auth Type        : None
If Events        : 1                    
Tot Rx Packets   : 44                   Tot Tx Packets   : 47
Rx Hellos        : 15                   Tx Hellos        : 15
Rx DBDs          : 2                    Tx DBDs          : 3
Rx LSRs          : 1                    Tx LSRs          : 1
Rx LSUs          : 15                   Tx LSUs          : 15
Rx LS Acks       : 11                   Tx LS Acks       : 13
Retransmits      : 0                    Discards         : 0
Bad Networks     : 0                    
Bad Areas        : 0                    Bad Dest Addrs   : 0
Bad Auth Types   : 0                    Auth Failures    : 0
Bad Neighbors    : 0                    Bad Pkt Types    : 0
Bad Lengths      : 0                    Bad Hello Int.   : 0
Bad Dead Int.    : 0                    Bad Options      : 0
Bad Versions     : 0                    Bad Checksums    : 0
===============================================================================
*A:7705:Dut-C# 
Table 21. OSPF sham link field descriptions (detailed)

Label

Description

Interface

The interface name

Remote Nbr

The remote neighbor IP address

Local IP Address

The IP address assigned the local end of the interface

Area Id

A 32-bit integer uniquely identifying the area to which this interface is connected; area ID 0.0.0.0 is used for the OSPF backbone

Last Enabled

The date and time that this interface was last enabled to run OSPF

Admin Status

Disabled: OSPF on this interface is administratively shut down

Enabled: OSPF on this interface is administratively enabled

Oper State

Down: the initial interface state. In this state, the lower-level protocols have indicated that the interface is unusable.

Waiting: the router is trying to determine the identity of the (backup) designated router for the network

Point To Point: the interface is operational and connects either to a physical point-to-point network, virtual link, or sham link

Designated Rtr: this router is the designated router for this network

Other Desig Rtr: the interface is operational and part of a broadcast or NBMA network on which another router has been selected to be the designated router

Backup Desig Rtr: this router is the backup designated router for this network

Transit Delay

The estimated number of seconds it takes to transmit a link-state update packet over this interface

Retrans Intrvl

The number of seconds between link-state advertisement retransmissions for adjacencies belonging to this interface. This value is also used when retransmitting database description and link-state request packets.

Hello Intrvl

The number of seconds between the Hello packets that the router sends on this interface. This value must be the same for all routers attached to a common network.

Rtr Dead Intrvl

The number of seconds that Hello packets have not been transmitted by a router before its neighbors declare the router down. This value should be a multiple of the Hello interval. This value must be the same for all routers attached to a common network.

Cfg Metric

The route cost metric to be advertised for this interface

Auth Type

Identifies the authentication procedure to be used for OSPF packets

None: routing exchanges over the network/subnet are not authenticated

Simple: a 64-bit field is configured on a per-network basis. All packets sent on a particular network must have this configured value in their OSPF header 64-bit authentication field. This essentially serves as a ‟clear” 64-bit password.

MD5: a shared secret key is configured on all routers attached to a common network or subnet. For each OSPF protocol packet, the key is used to generate and verify a ‟message digest” that is appended to the end of the OSPF packet.

If Events

The number of times this interface has changed its state, or an error has occurred since the interface was last enabled

Tot Rx Packets

The total number of OSPF packets received on this interface since the interface was last enabled

Tot Tx Packets

The total number of OSPF packets transmitted on this interface since the interface was last enabled

Rx Hellos

The total number of OSPF Hello packets received on this interface since the interface was last enabled

Tx Hellos

The total number of OSPF Hello packets transmitted on this interface since the interface was last enabled

Rx DBDs

The total number of OSPF database description packets received on this interface since the interface was last enabled

Tx DBDs

The total number of OSPF database description packets transmitted on this interface since the interface was last enabled

Rx LSRs

The total number of Link-State Requests (LSRs) received on this interface since the interface was last enabled

Tx LSRs

The total number of Link-State Requests (LSRs) transmitted on this interface since the interface was last enabled

Rx LSUs

The total number of Link-State Updates (LSUs) received on this interface since the interface was last enabled

Tx LSUs

The total number of Link-State Updates (LSUs) transmitted on this interface since the interface was last enabled

Rx LS Acks

The total number of Link-State Acknowledgments received on this interface since the interface was last enabled

Tx LS Acks

The total number of Link-State Acknowledgments transmitted on this interface since the interface was last enabled

Retransmits

The total number of OSPF retransmits sent on this interface since the interface was last enabled

Discards

The total number of OSPF packets discarded on this interface since the interface was last enabled

Bad Networks

The total number of OSPF packets received with invalid network or mask since the interface was last enabled

Bad Areas

The total number of OSPF packets received with an area mismatch since this interface was last enabled

Bad Dest Addrs

The total number of OSPF packets received with the incorrect IP destination address since this interface was last enabled

Bad Auth Types

The total number of OSPF packets received with an invalid authorization type since this interface was last enabled

Auth Failures

The total number of OSPF packets received with an invalid authorization key since this interface was last enabled

Bad Neighbors

The total number of OSPF packets received where the neighbor information does not match the information this router has for the neighbor since this interface was last enabled

Bad Pkt Types

The total number of OSPF packets received with an invalid OSPF packet type since this interface was last enabled

Bad Lengths

The total number of OSPF packets received on this interface with a total length not equal to the length given in the packet since the interface was last enabled

Bad Hello Int.

The total number of OSPF packets received where the hello interval given in the packet is not equal to that configured on this interface since the interface was last enabled

Bad Dead Int.

The total number of OSPF packets received where the dead interval given in the packet is not equal to that configured on this interface since the interface was last enabled

Bad Options

The total number of OSPF packets received with an option that does not match those configured for this interface or area since the interface was last enabled

Bad Versions

The total number of OSPF packets received with bad OSPF version numbers since this interface was last enabled

Bad Checksums

The total number of OSPF packets received with bad checksums since this interface was last enabled
sham-link-neighbor
Syntax

sham-link-neighbor [detail]

sham-link-neighbor interface-name remote ip-address [detail]

Context

show>router>ospf

Description

This command displays OSPF sham-link neighbor information.

Parameters
interface-name

displays only the sham-link neighbor information for the specified interface name, up to 32 characters

ip-address

displays only the sham-link neighbor information for the specified remote neighbor IP address, in the format a.b.c.d

detail

displays detailed OSPF sham-link neighbor information

Output

The following output is an example of sham-link neighbor information:

Output example 
*A:7705:Dut-C# show router 1000 ospf sham-link-neighbor 
=============================================================================
Rtr vprn1000 OSPFv2 Instance 0 Sham-Link Neighbors
=============================================================================
Interface Name                    Neighbor IP      State      RetxQ   DeadTime
                                                                      
-----------------------------------------------------------------------------
myLocalShamItf                    50.0.0.2         Full       0       31
-----------------------------------------------------------------------------
No. of Neighbors: 1
=============================================================================
*A:7705:Dut-C# 
Table 22. OSPF sham-link neighbor field descriptions (standard)

Label

Description

Interface Name

The interface name

Neighbor IP

The remote neighbor IP address

State

Down: the initial state of a neighbor conversation. It indicates that there has been no recent information received from the neighbor.

Attempt: this state is only valid for neighbors attached to NBMA networks. It indicates that no recent information has been received from the neighbor but that a more concerted effort should be made to contact the neighbor.

Init: in this state, a Hello packet has recently been received from the neighbor. However, bidirectional communication has not yet been established with the neighbor (that is, the router did not appear in the neighbor’s Hello packet).

Two Way: in this state, communication between the two routers is bidirectional

ExchStart: the first step in creating an adjacency between the two neighboring routers. The goal of this step is to decide which router is the master and to decide upon the initial database descriptor sequence number.

Exchange: in this state, the router is describing its entire link-state database by sending database description packets to the neighbor

Loading: in this state, Link-State Request packets are sent to the neighbor asking for the more recent LSAs that have been discovered (but not yet received) in the Exchange state

Full: in this state, the neighboring routers are fully adjacent. These adjacencies will now appear in router LSAs and network LSAs.

RetxQ

The current length of the retransmission queue

DeadTime

The time until this neighbor is declared down

No. of Neighbors

The number of adjacent OSPF neighbors on this interface
Output example 
*A:7705:Dut-C# show router 1000 ospf sham-link-neighbor detail 
===============================================================================
Rtr vprn1000 OSPFv2 Instance 0 Sham-Link Neighbors (detail)
===============================================================================
-------------------------------------------------------------------------------
Interface: myLocalShamItf Remote Nbr : 50.0.0.2
-------------------------------------------------------------------------------
Area Id : 0.0.0.0
Neighbor State   : Full                 Options          : -E-- - -O--
Last Event Time  : 02/24/2021 17:48:22  Last Restart at  : Never
Up Time          : 0d 00:02:22          Time Before Dead : 37 sec
GR Helper        : Not Helping          GR Helper Age    : 0 sec
GR Exit Reason   : None                 GR Restart Reason: Unknown
Retrans Q Length : 0                    Events           : 5
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
Num Restarts     : 0                    
===============================================================================
*A:7705:Dut-C#
Table 23. OSPF sham-link neighbor field descriptions (detailed)

Label

Description

Interface

The interface name

Remote Nbr

The remote neighbor IP address

Area Id

A 32-bit integer uniquely identifying the area to which this interface is connected; area ID 0.0.0.0 is used for the OSPF backbone

Neighbor State

Down: the initial state of a neighbor conversation. It indicates that there has been no recent information received from the neighbor.

Attempt: this state is only valid for neighbors attached to NBMA networks. It indicates that no recent information has been received from the neighbor, but that a more concerted effort should be made to contact the neighbor.

Init: in this state, a Hello packet has recently been received from the neighbor. However, bidirectional communication has not yet been established with the neighbor (that is, the router did not appear in the neighbor’s Hello packet).

Two Way: in this state, communication between the two routers is bidirectional

ExchStart: the first step in creating an adjacency between the two neighboring routers. The goal of this step is to decide which router is the master and to decide upon the initial database descriptor sequence number.

Exchange: in this state, the router is describing its entire link-state database by sending database description packets to the neighbor

Loading: in this state, Link-State Request packets are sent to the neighbor asking for the more recent LSAs that have been discovered (but not yet received) in the Exchange state

Full: in this state, the neighboring routers are fully adjacent. These adjacencies will now appear in router LSAs and network LSAs.

Options

E: external routes support

MC: multicast support (not applicable)

N/P: type 7 LSA support

EA: external attribute LSA support

DC: demand circuit support

O: opaque LSA support

Last Event Time

The time that the last event occurred that affected the adjacency to the neighbor

Last Restart at

The local time of the last graceful restart

Up Time

The uninterrupted length of time that the adjacency to this neighbor has been up. The Last Event Time field shows when the last state change occurred.

Time Before Dead

The time until this neighbor is declared down; this timer is set to the dead router interval when a valid Hello packet is received from the neighbor

GR Helper

Graceful restart helper mode, either Helping or Not Helping

GR Helper Age

The time elapsed since GR Helper was enabled

GR Exit Reason

The reason for a graceful restart exit

GR Restart Reason

The reason for a graceful restart

Retrans Q Length

The current length of the retransmission queue

Events

The number of times this neighbor relationship has changed state, or an error has occurred

Bad Nbr States

The total number of OSPF packets received when the neighbor state was not expecting to receive this packet type since this interface was last enabled

LSA Inst fails

The total number of times that an LSA could not be installed into the link-state database due to a resource allocation issue since this interface was last enabled

Bad Seq Nums

The total number of times that a database description packet was received with a sequence number mismatch since this interface was last enabled

Bad MTUs

The total number of times that the MTU in a received database description packet was larger than the MTU of the receiving interface since this interface was last enabled

Bad Packets

The total number of times that an LS update was received with an illegal LS type or an option mismatch since this interface was last enabled

LSA not in LSDB

The total number of times that an LS request was received for an LSA not installed in the LSDB of this router since this interface was last enabled

Option Mismatches

The total number of times that an LS update was received with an option mismatch since this interface was last enabled

Nbr Duplicates

The total number of times that a duplicate database description packet was received during the exchange state since this interface was last enabled

Num Restarts

The total number of graceful restarts
spf
Syntax

spf [lfa]

Context

show>router>ospf

show>router>ospf3

Description

This command displays statistics of shortest path first (SPF) calculations.

Parameters
lfa

displays LFA next hop information

Output

The following output is an example of SPF information, and SPF field descriptions describes the fields.

Output example 
A:ALU-A# show router ospf spf lfa
===============================================================================
Rtr Base OSPFv2 Instance 0 SPF Statistics
===============================================================================
 Total SPF Runs          :  109
 Last Full SPF run @     :  11/07/2015 18:43:07
 Last Full SPF Time      :  < 0.01 secs
      Intra SPF Time     :  < 0.01 secs
      Inter SPF Time     :  < 0.01 secs
      Extern SPF Time    :  < 0.01 secs
      RTM Updt Time      :  < 0.01 secs

 Min/Avg/Max Full SPF Times   :  0.02/0.00/0.06 secs
 Min/Avg/Max RTM Updt Times   :  0.02/0.00/0.06 secs

 Total Sum Incr SPF Runs :  333

 Total Ext Incr SPF Runs :  0

 Total LFA SPF Runs      :  5
 Last LFA SPF run @      :  11/07/2015 18:43:07
 Last LFA SPF Time       :  < 0.01 secs
 Min/Avg/Max  LFA  SPF Times : 0.00/0.00/0.00 secs
===============================================================================
Table 24. SPF field descriptions

Label

Description

Total SPF Runs

The total number of incremental SPF runs triggered by new or updated LSAs

Last Full SPF run @

The date and time that the external OSPF SPF was last run

Last Full SPF Time

The length of time, in seconds, when the last full SPF was run

Intra SPF Time

The time that intra-area SPF was last run on this area

Inter SPF Time

The total number of incremental SPF runs triggered by new or updated type 3 and type 4 summary LSAs

Extern SPF Time

The total number of incremental SPF runs triggered by new or updated type 5 external LSAs

RTM Updt Time

The time, in hundredths of seconds, used to perform a total SPF calculation

Min/Avg/Max Full SPF Times

Min: the minimum time, in hundredths of seconds, used to perform a total SPF calculation

Avg: the average time, in hundredths of seconds, of all the SPF calculations performed by this OSPF router

Max: the maximum time, in hundredths of seconds, used to perform a total SPF calculation

Min/Avg/Max RTM Updt Times

Min: the minimum time, in hundredths of seconds, used to perform an RTM update

Note: the RTM update is performed after the SPF calculation. The update is used to inform the routing table manager of any route or cost changes from the latest SPF calculation.

Avg: the average time, in hundredths of seconds, of all the RTM updates performed by this OSPF router

Max: the maximum time, in hundredths of seconds, used to perform an RTM update

Total Sum Incr SPF Runs

The total number of incremental SPF runs triggered by new or updated type 3 and type 4 summary LSAs

Total Ext Incr SPF Runs

The total number of incremental SPF runs triggered by new or updated type 5 external LSAs

Total LFA SPF Runs

The total number of incremental LFA SPF runs triggered by new or updated LSAs

Last LFA SPF run @

The date and time that the external OSPF LFA SPF was last run

Last LFA SPF Time

The length of time, in seconds, when the last LFA SPF was run

Min/Avg/Max LFA SPF Times

Min: the minimum time, in hundredths of seconds, used to perform an LFA SPF calculation

Avg: the average time, in hundredths of seconds, of all the LFA SPF calculations performed by this OSPF router

Max: the maximum time, in hundredths of seconds, used to perform an LFA SPF calculation
statistics
Syntax

statistics

Context

show>router>ospf

show>router>ospf3

Description

This command displays the global OSPF statistics.

Output

The following output is an example of OSPF statistical information, and OSPF statistics field descriptions describes the fields.

Output example 
A:ALU-A# show router ospf statistics
===============================================================================
Rtr Base OSPFv2 Instance 0 Statistics
===============================================================================
Rx Packets         : 308462             Tx Packets         : 246800
Rx Hellos          : 173796             Tx Hellos          : 149062
Rx DBDs            : 67                 Tx DBDs            : 48
Rx LSRs            : 21                 Tx LSRs            : 19
Rx LSUs            : 105672             Tx LSUs            : 65530
Rx LS Acks         : 28906              Tx LS Acks         : 32141
New LSAs Recvd     : 38113              New LSAs Orig      : 21067
Ext LSAs Count     : 17                 No of Areas        : 3
No of Interfaces   : 327                No of Neighbors    : 0
Retransmits        : 46                 Discards           : 0
Bad Networks       : 0                  Bad Virt Links     : 0
Bad Areas          : 0                  Bad Dest Addrs     : 0
Bad Auth Types     : 0                  Auth Failures      : 0
Bad Neighbors      : 0                  Bad Pkt Types      : 0
Bad Lengths        : 0                  Bad Hello Int.     : 0
Bad Dead Int.      : 0                  Bad Options        : 0
Bad Versions       : 0                  Bad Checksums      : 0
SID SRGB errors    : 0                  SID dupl errors    : 0
Failed SPF Attempts: 0                  Bad MTUs           : 0
CSPF Requests      : 0                  CSPF Request Drops : 0
CSPF Path Found    : 0                  CSPF Path Not Found: 0
Total SPF Runs     : 1                  Total LFA SPF Runs : 1
Total RLFA SPF Runs: 0
===============================================================================
Table 25. OSPF statistics field descriptions

Label

Description

Rx Packets

The total number of OSPF packets received on all OSPF enabled interfaces

Tx Packets

The total number of OSPF packets transmitted on all OSPF enabled interfaces

Rx Hellos

The total number of OSPF Hello packets received on all OSPF enabled interfaces

Tx Hellos

The total number of OSPF Hello packets transmitted on all OSPF enabled interfaces

Rx DBDs

The total number of OSPF database description packets received on all OSPF enabled interfaces

Tx DBDs

The total number of OSPF database description packets transmitted on all OSPF enabled interfaces

Rx LSRs

The total number of OSPF Link-State Requests (LSRs) received on all OSPF enabled interfaces

Tx LSRs

The total number of OSPF Link-State Requests (LSRs) transmitted on all OSPF enabled interfaces

Rx LSUs

The total number of OSPF Link-State Updates (LSUs) received on all OSPF enabled interfaces

Tx LSUs

The total number of OSPF Link-State Updates (LSUs) transmitted on all OSPF enabled interfaces

Rx LS Acks

The total number of OSPF Link-State Acknowledgments received on all OSPF enabled interfaces

New LSAs Recvd

The total number of new OSPF Link-State Advertisements received on all OSPF enabled interfaces

New LSAs Orig

The total number of new OSPF Link-State Advertisements originated on all OSPF enabled interfaces

Ext LSAs Count

The total number of OSPF External Link-State Advertisements

No of Areas

The number of areas configured for OSPF (maximum 4)

No of Interfaces

The number of interfaces configured for OSPF on the router

No of Neighbors

The number of adjacent OSPF neighbors on this interface

Retransmits

The total number of OSPF Retransmits transmitted on all OSPF enabled interfaces

Discards

The total number of OSPF packets discarded on all OSPF enabled interfaces

Bad Networks

The total number of OSPF packets received on all OSPF enabled interfaces with invalid network or mask

Bad Virt Links

The total number of OSPF packets received on all OSPF enabled interfaces that are destined for a virtual link that does not exist

Bad Areas

The total number of OSPF packets received on all OSPF enabled interfaces with an area mismatch

Bad Dest Addrs

The total number of OSPF packets received on all OSPF enabled interfaces with the incorrect IP destination address

Bad Auth Types

The total number of OSPF packets received on all OSPF enabled interfaces with an invalid authorization type

Auth Failures

The total number of OSPF packets received on all OSPF enabled interfaces with an invalid authorization key

Bad Neighbors

The total number of OSPF packets received on all OSPF enabled interfaces where the neighbor information does not match the information this router has for the neighbor

Bad Pkt Types

The total number of OSPF packets received on all OSPF enabled interfaces with an invalid OSPF packet type

Bad Lengths

The total number of OSPF packets received on all OSPF enabled interfaces with a total length not equal to the length given in the packet itself

Bad Hello Int.

The total number of OSPF packets received on all OSPF enabled interfaces where the hello interval given in the packet was not equal to that configured for the respective interface

Bad Dead Int.

The total number of OSPF packets received on all OSPF enabled interfaces where the dead interval given in the packet was not equal to that configured for the respective interface

Bad Options

The total number of OSPF packets received on all OSPF enabled interfaces with an option that does not match those configured for the respective interface or area

Bad Versions

The total number of OSPF packets received on all OSPF enabled interfaces with bad OSPF version numbers

Bad Checksums

The total number of OSPF packets received with bad checksums since this interface was last enabled

SID SRGB errors

The total number of SID SRGB errors

SID dupl errors

The total number of SID duplication errors

Failed SPF Attempts

The total number of failed SPF calculation attempts

Bad MTUs

The total number of MTU mismatch

CSPF Requests

The total number of constraint-based SPF requests

CSPF Request Drops

The total number of constraint-based SPF requests dropped

CSPF Path Found

A path that fulfills the set of constraints defined in MPLS traffic engineering

CSPF Path Not Found

A path that does not fulfill the set of constraints defined in MPLS traffic engineering

Total SPF Runs

The total number of incremental SPF runs triggered by new or updated LSAs

Total LFA SPF Runs

The total number of incremental LFA SPF runs triggered by new or updated LSAs
status
Syntax

status

Context

show>router>ospf

show>router>ospf3

Description

This command displays the general status of OSPF.

Output

The following output is an example of OSPF status information, and OSPF status field descriptions describes the fields.

Output example 
A:ALU-A# show router ospf status
===============================================================================
Rtr Base OSPFv2 Instance 0 Status
===============================================================================
OSPF Cfg Router Id           : 10.0.0.0
OSPF Oper Router Id          : 10.10.10.104
OSPF Version                 : 2
OSPF Admin Status            : Enabled
OSPF Oper Status             : Enabled
GR Helper Mode               : Enabled
Preference                   : 10
External Preference          : 150
Backbone Router              : True
Area Border Router           : False
AS Border Router             : False
Opaque LSA Support           : True
Traffic Engineering Support  : False
RFC 1583 Compatible          : True
Demand Exts Support          : False
In Overload State            : False
In External Overflow State   : False
Exit Overflow Interval       : 0
Last Overflow Entered        : Never
Last Overflow Exit           : Never
External LSA Limit           : -1
Reference Bandwidth          : 100,000,000 Kbps
Init SPF Delay               : 1000 msec
Sec SPF Delay                : 1000 msec
Max SPF Delay                : 10000 msec
Min LS Arrival Interval      : 1000 msec
Init LSA Gen Delay           : 5000 msec
Sec LSA Gen Delay            : 5000 msec
Max LSA Gen Delay            : 5000 msec
Last Ext SPF Run             : Never
Ext LSA Cksum Sum            : 0x0
OSPF Last Enabled            : 01/12/2015 15:32:11
Unicast Import               : True
Export Policies              : None
Import Policies              : None
Lfa Policies                 : pol1
                             : pol2
                             : pol3
                             : pol4
                             : pol5
OSPF Ldp Sync Admin Status   : Enabled
LDP-over-RSVP                : Disabled
RSVP-Shortcut                : Enabled
Advertise-Tunnel-Link        : Disabled
LFA                          : Enabled
Remote-LFA                   : Enabled
Max PQ Cost                  : 65535
TI-LFA                       : Disabled
Max SR FRR Labels            : 2
Export Limit                 : 0
Export Limit Log Percent     : 0
Total Exp Routes             : 0
Segment Routing              : Disabled
Database export              : Disabled
ASN                          : n/a
Entropy Label                : Enabled
Override ELC                 : Disabled
===============================================================================
A:ALU-A#  
Table 26. OSPF status field descriptions

Label

Description

OSPF Cfg Router Id

The router ID configured for the router

OSPF Oper Router ID

The operational router ID. The 7705 SAR defaults to the system IP address or, if not configured, the last 4 bytes of the system MAC address.

OSPF Version

The current version number of the OSPF protocol: 2

OSPF Admin Status

Disabled: the OSPF process is disabled on all interfaces

Enabled: the OSPF process is active on at least one interface

OSPF Oper Status

Disabled: the OSPF process is not operational on all interfaces

Enabled: the OSPF process is operational on at least one interface

GR Helper Mode

Disabled: graceful restart helper is disabled

Enabled: graceful restart helper is enabled

Preference

The route preference for OSPF internal routes

External Preference

The route preference for OSPF external routes

Backbone Router

False: this router is not configured as an OSPF backbone router

True: this router is configured as an OSPF backbone router

Area Border Router

False: this router is not configured as an area border router

True: this router is configured as an area border router

AS Border Router

False: this router is not configured as an autonomous system border (boundary) router

True: this router is configured as an autonomous system border (boundary) router

Opaque LSA Support

False: this router does not support opaque LSAs

True: this router supports opaque LSAs

Traffic Engineering Support

False: this router does not support traffic engineering

True: this router supports traffic engineering

RFC 1583 Compatible

False: this router is not RFC 1583 compatible

True: this router is RFC 1583 compatible

Demand Exts Support

False: this router does not demand external route support

True: this router does demand external route support

In Overload State

False: this router is not in an overload state

True: this router is in an overload state

In External Overflow State

False: this router is not in an external overflow state

True: this router is in an external overflow state

Exit Overflow Interval

The time to wait before the router exits the overflow state

Last Overflow Entered

Indicates when the router last entered an overflow state

Last Overflow Exit

Indicates when the router last exited an overflow state

External LSA limit

The number of external LSAs allowed

Reference bandwidth

The configured reference bandwidth, in kilobits per second

Init SPF Delay

The initial SPF calculation delay

Sec SPF Delay

The SPF calculation delay between the first and second calculations

Max SPF Delay

The maximum interval between two consecutive SPF calculations

Min LS Arrival Interval

The minimum interval between LSAs

Init LSA Gen Delay

The initial LSA generation delay

Sec LSA Gen Delay

The delay between the generation of the first and second LSAs

Max LSA Gen Delay

The maximum interval between two consecutive LSAs

Last Ext SPF Run

The time that the last external SPF calculation was run

Ext LSA Cksum Sum

The 32-bit unsigned sum of the LS checksums of the external LSAs contained in this area’s link-state database

OSPF Last Enabled

The time that OSPF was last enabled on the interface

Unicast Import

Indicates whether routes are imported into the unicast RTM

Export Policies

Indicates whether any export routing policies have been applied to the OSPF interface

Import Policies

Indicates whether any import routing policies have been applied to the OSPF interface

Lfa Policies

Lists the defined LFA policies

OSPF Ldp Sync Admin Status

Indicates whether the IGP-LDP synchronization feature is enabled or disabled on all interfaces participating in the OSPF routing protocol

RSVP-Shortcut

Indicates whether RSVP-TE shortcuts (IGP shortcuts) are enabled

Advertise-Tunnel-Link

Indicates whether forwarding adjacencies are enabled

LFA

Indicates whether LFA is enabled

Remote-LFA

Indicates whether LFA is enabled on the remote device

Max PQ Cost

Indicates the configured maximum PQ cost under the loopfree-alternate command

TI-LFA

Indicates if TI-LFA is enabled or disabled under the loopfree-alternate command

Max SR FRR Labels

The maximum number of segment routing FRR labels

Export Limit

n/a

Export Limit Log Percent

n/a

Total Exp Routes

Indicates the total number of export routes

Segment Routing

Indicates whether segment routing is enabled

Database export

Indicates whether database export is enabled

ASN

n/a

Entropy Label

Indicates whether entropy label is enabled

Override ELC

Indicates whether entropy label capability is enabled for BGP tunnels
virtual-link
Syntax

virtual-link database [detail]

virtual-link [detail]

Context

show>router>ospf

show>router>ospf3

Description

This command displays information for OSPF virtual links.

Parameters
database

displays the virtual link database. This parameter applies only in the ospf context.

detail

provides operational and statistical information for virtual links associated with this router

Output

The following output is an example of OSPF virtual link information, and Virtual link field descriptions describes the fields.

Output example 
A:ALU-A# show router ospf virtual-link
=================================================================
Rtr Base OSPFv2 Instance 0 Virtual Links
=================================================================
Nbr Rtr Id      Area Id         Local Interface     Metric State
-----------------------------------------------------------------
10.0.0.10      0.0.0.1         10.1.7.12          300    PToP
10.0.0.10      0.0.0.2         10.2.7.12          300    PToP
-----------------------------------------------------------------
No. of OSPF Virtual Links: 2
=================================================================
A:ALU-A# 

A:ALU-A# show router ospf virtual-link detail
===============================================================================
Rtr Base OSPFv2 Instance 0 Virtual Links (detail)
===============================================================================
Neighbor Router Id :  10.0.0.10
-------------------------------------------------------------------------------
Nbr Router Id  : 10.0.0.10             Area Id        : 0.0.0.1
Local Interface: 10.1.7.12             Metric         : 300
State          : Point To Point         Admin State    : Up
Hello Intrvl   : 10 sec                 Rtr Dead Intrvl: 60 sec
Tot Rx Packets : 43022                  Tot Tx Packets : 42964
Rx Hellos      : 24834                  Tx Hellos      : 24853
Rx DBDs        : 3                      Tx DBDs        : 2
Rx LSRs        : 0                      Tx LSRs        : 0
Rx LSUs        : 15966                  Tx LSUs        : 16352
Rx LS Acks     : 2219                   Tx LS Acks     : 1757
Retransmits    : 0                      Discards       : 0
Bad Networks   : 0                      Bad Versions   : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Retrans Intrvl : 5 sec                  Transit Delay  : 1 sec
Last Event     : 11/07/2015 17:11:56    Authentication : None
-------------------------------------------------------------------------------
Neighbor Router Id : 10.0.0.10
-------------------------------------------------------------------------------
Nbr Router Id  : 10.0.0.10              Area Id        : 0.0.0.2
Local Interface: 10.2.7.12              Metric         : 300
State          : Point To Point         Admin State    : Up
Hello Intrvl   : 10 sec                 Rtr Dead Intrvl: 60 sec
Tot Rx Packets : 43073                  Tot Tx Packets : 43034
Rx Hellos      : 24851                  Tx Hellos      : 24844
Rx DBDs        : 3                      Tx DBDs        : 2
Rx LSRs        : 1                      Tx LSRs        : 1
Rx LSUs        : 18071                  Tx LSUs        : 17853
Rx LS Acks     : 147                    Tx LS Acks     : 334
Retransmits    : 0                      Discards       : 0
Bad Networks   : 0                      Bad Versions   : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Retrans Intrvl : 5 sec                  Transit Delay  : 1 sec
Last Event     : 11/07/2015 17:12:00    Authentication : None
===============================================================================
A:ALU-A# 
Table 27. Virtual link field descriptions

Label

Description

Nbr Rtr ID

The router IDs of neighboring routers

Area Id

A 32-bit integer that identifies an area

Local Interface

The IP address of the local egress interface used to maintain the adjacency to reach this virtual neighbor

Metric

The metric value associated with the route. This value is used when importing this static route into other protocols. When the metric is configured as 0, then the metric configured in OSPF, default-metric, applies. This value is also used to determine which static route to install in the forwarding table.

State

The operational state of the virtual link to the neighboring router

Authentication

Specifies whether authentication is enabled for the interface or virtual link

Hello Intrvl

The length of time, in seconds, between the Hello packets that the router sends on the interface

Rtr Dead Intrvl

The total number of OSPF packets received where the dead interval given in the packet was not equal to that configured on this interface since the OSPF admin status was enabled

Tot Rx Packets

The total number of OSPF packets received on this interface since the OSPF admin status was enabled

Rx Hellos

The total number of OSPF Hello packets received on this interface since the OSPF admin status was enabled

Rx DBDs

The total number of OSPF database description packets received on this interface since the OSPF admin status was enabled

Rx LSRs

The total number of Link-State Requests (LSRs) received on this interface since the OSPF admin status was enabled

Rx LSUs

The total number of Link-State Updates (LSUs) received on this interface since the OSPF admin status was enabled

Rx LS Acks

The total number of Link-State Acknowledgments received on this interface since the OSPF admin status was enabled

Tot Tx Packets

The total number of OSPF packets transmitted on this interface since the OSPF admin status was enabled

Tx Hellos

The total number of OSPF Hello packets transmitted on this interface since the OSPF admin status was enabled

Tx DBDs

The total number of OSPF database description packets transmitted on this interface since the OSPF admin status was enabled

Tx LSRs

The total number of OSPF Link-State Requests (LSRs) transmitted on this interface since the OSPF admin status was enabled

Tx LSUs

The total number of OSPF Hello packets transmitted on this interface since the OSPF admin status was enabled

Tx LS Acks

The total number of OSPF Link-State Acknowledgments transmitted on this interface since the OSPF admin status was enabled

Retransmits

The total number of OSPF retransmits sent on this interface since the OSPF admin status was last enabled

Discards

The total number of OSPF packets discarded on this interface since the OSPF admin status was last enabled

Bad Networks

The total number of OSPF packets received with invalid network or mask since the OSPF admin status was last enabled

Bad Versions

The total number of OSPF packets received with bad OSPF version numbers since the OSPF admin status was last enabled

Bad Areas

The total number of OSPF packets received with an area mismatch since the OSPF admin status was last enabled

Bad Dest Addrs

The total number of OSPF packets received with the incorrect IP destination address since the OSPF admin status was last enabled

Bad Auth Types

The total number of OSPF packets received with an invalid authorization type since the OSPF admin status was last enabled

Auth Failures

The total number of OSPF packets received with an invalid authorization key since the OSPF admin status was last enabled

Bad Neighbors

The total number of OSPF packets received where the neighbor information does not match the information this router has for the neighbor since the OSPF admin status was last enabled

Bad Pkt Types

The total number of OSPF packets received with an invalid OSPF packet type since the OSPF admin status was last enabled

Bad Lengths

The total number of OSPF packets received on this interface with a total length not equal to the length given in the packet itself since the OSPF admin status was last enabled

Bad Hello Int.

The total number of OSPF packets received where the hello interval given in the packet was not equal to that configured on this interface since the OSPF admin status was last enabled

Bad Dead Int.

The total number of OSPF packets received where the dead interval given in the packet was not equal to that configured on this interface since the OSPF admin status was last enabled

Bad Options

The total number of OSPF packets received with an option that does not match those configured for this interface or area since the OSPF admin status was last enabled

Retrans Intrvl

The length of time, in seconds, that OSPF waits before retransmitting an unacknowledged link-state advertisement (LSA) to an OSPF neighbor

Transit Delay

The time, in seconds, that it takes to transmit a link-state advertisement (LSA) on the interface or virtual link

Last Event

The date and time that an event was last associated with this OSPF interface
virtual-neighbor
Syntax

virtual-neighbor [remote ip-address] [detail]

virtual-neighbor [remote ipv6-address] [detail]

Context

show>router>ospf

show>router>ospf3

Description

This command displays virtual neighbor information.

The detail option produces a large amount of data. It is recommended that this option be used only when requesting information about a specific neighbor.

Parameters
ip-address

specifies the IPv4 address of a remote virtual neighbor. This parameter applies in the ospf context and reduces the amount of output displayed.

ipv6-address

specifies the IPv6 address of a remote virtual neighbor. This parameter applies in the ospf3 context and reduces the amount of output displayed.

detail

displays detailed information for the virtual neighbor

Output

The following output is an example of OSPF virtual neighbor information, and Virtual neighbor field descriptions describes the fields.

Output example 
A:ALU-A# show router ospf virtual-neighbor
===============================================================================
Rtr Base OSPFv2 Instance 0 Virtual Neighbors
===============================================================================
Nbr IP Addr     Nbr Rtr Id      Nbr State Transit Area    RetxQ Len  Dead Time
-------------------------------------------------------------------------------
10.1.6.10      10.0.0.10      Full      0.0.0.1         0          58
10.2.9.10      10.0.0.10      Full      0.0.0.2         0          52
-------------------------------------------------------------------------------
No. of Neighbors: 2
===============================================================================
A:ALU-A# 

A:ALU-A# show router ospf virtual-neighbor detail
===============================================================================
Rtr Base OSPFv2 Instance 0 Virtual Neighbors (detail)
===============================================================================
Virtual Neighbor Router Id : 10.0.0.10
-------------------------------------------------------------------------------
Neighbor IP Addr : 10.1.6.10            Neighbor Rtr Id  : 10.0.0.10
Neighbor State   : Full                 Transit Area     : 0.0.0.1
Retrans Q Length : 0                    Options          : -E--
Events           : 4                    Last Event Time  : 11/07/2015 17:11:56
Up Time          : 2d 17:47:17          Time Before Dead : 57 sec
Bad Nbr States   : 1                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
-------------------------------------------------------------------------------
Virtual Neighbor Router Id : 10.0.0.10
-------------------------------------------------------------------------------
Neighbor IP Addr : 10.2.9.10            Neighbor Rtr Id  : 10.0.0.10
Neighbor State   : Full                 Transit Area     : 0.0.0.2
Retrans Q Length : 0                    Options          : -E--
Events           : 4                    Last Event Time  : 11/07/2015 17:11:59
Up Time          : 2d 17:47:14          Time Before Dead : 59 sec
Bad Nbr States   : 1                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
===============================================================================
A:ALU-A# 
Table 28. Virtual neighbor field descriptions

Label

Description

Nbr IP Addr

The IP address this neighbor is using in its IP source address. On links with no address, this will not be 0.0.0.0, but the address of another of the neighbor's interfaces.

Nbr Rtr ID

The router IDs of neighboring routers

Transit Area

The transit area ID that links the backbone area with the area that has no physical connection with the backbone

RetxQ Len/ Retrans Q Length

The current length of the retransmission queue

No. of Neighbors

The total number of OSPF neighbors adjacent on this interface, in a state of INIT or greater, since the OSPF admin status was enabled

Nbr State

The operational state of the virtual link to the neighboring router

Options

The total number of OSPF packets received with an option that does not match those configured for this virtual interface or transit area since the OSPF admin status was enabled

Events

The total number of events that have occurred since the OSPF admin status was enabled

Last Event Time

The date and time that an event was last associated with this OSPF interface

Up Time

The uninterrupted time, in hundredths of seconds, that the adjacency to this neighbor has been up

Dead Time/Time Before Dead

The amount of time, in seconds, until the dead router interval expires

Bad Nbr States

The total number of OSPF packets received where the neighbor information does not match the information this router has for the neighbor since the OSPF admin status was last enabled

LSA Inst fails

The total number of times an LSA could not be installed into the LSDB due to a resource allocation issue since the OSPF admin status was last enabled

Bad Seq Nums

The total number of times that a database description packet was received with a sequence number mismatch since the OSPF admin status was last enabled

Bad MTUs

The total number of times that the MTU in a received database description packet was larger than the MTU of the receiving interface since the OSPF admin status was enabled

Bad Packets

The total number of times that an LS update was received with an illegal LS type or an option mismatch since the OSPF admin status was enabled

LSA not in LSDB

The total number of times that an LS request was received for an LSA not installed in the LSDB of this router since the OSPF admin status was enabled

Option Mismatches

The total number of times that an LS update was received with an option mismatch since the OSPF admin status was enabled

Nbr Duplicates

The total number of times that a duplicate database description packet was received during the Exchange state since the OSPF admin status was enabled

Clear commands

ospf
Syntax

ospf

Context

clear>router

Description

This command clears and resets OSPF protocol entities.

ospf3
Syntax

ospf3

Context

clear>router

Description

This command clears and resets OSPFv3 protocol entities.

database
Syntax

database [purge]

Context

clear>router>ospf

clear>router>ospf3

Description

This command clears all LSAs received from other nodes and refreshes all self-originated LSAs.

Parameters
purge

clears all self-originated LSAs and reoriginates all self-originated LSAs

export
Syntax

export

Context

clear>router>ospf

clear>router>ospf3

Description

This command re-evaluates all effective export route policies.

neighbor
Syntax

neighbor [ip-int-name | ip-address]

Context

clear>router>ospf

clear>router>ospf3

Description

This command marks the neighbor as dead and reinitiates the affected adjacencies.

Parameters
ip-int-name

clears all neighbors for the interface specified by this interface name

ip-address

clears all neighbors for the interface specified by this IP address

statistics
Syntax

statistics

Context

clear>router>ospf

clear>router>ospf3

Description

This command clears all neighbor, router, interface, SPF, and global statistics for OSPF.

Monitor commands

ospf
Syntax

ospf

Context

monitor>router

Description

This command enables the context to configure monitor commands for the OSPF instance.

ospf3
Syntax

ospf3

Context

monitor>router

Description

This command enables the context to configure monitor commands for the OSPFv3 instance.

interface
Syntax

interface interface [interface...(up to 5 max)] [interval seconds] [repeat repeat] [absolute | rate]

Context

monitor>router>ospf

monitor>router>ospf3

Description

This command displays statistics for OSPF or OSPFv3 interfaces at the configured interval until the configured count is reached.

The first screen displays the current statistics related to the OSPF or OSPFv3 interface. The subsequent statistical information listed for each interval is displayed as a delta to the previous display.

When the keyword rate is specified, the rate-per-second for each statistic is displayed instead of the delta.

Monitor commands are similar to show commands but only statistical information displays. Monitor commands display the selected statistics according to the configured number of times at the interval specified.

Parameters
interface

the name of the IP interface or the IP address

Values

ip-int-name | ip-address (OSPF only)

seconds

configures the interval for each display, in seconds

Values

3 to 60

Default

10

repeat

configures how many times the command is repeated

Values

1 to 999

Default

10

absolute

displays raw statistics, without processing. No calculations are performed on the delta or rate statistics.

rate

displays rate-per-second for each statistic instead of the delta

Output

The following output is an example of OSPF interface information.

Output example 
A:ALA-12>monitor>router>ospf# interface to-104 interval 3 repeat 3 absolute
===============================================================================
Monitor statistics for OSPF Interface "to-104"
===============================================================================
At time t = 0 sec (Base Statistics)
-------------------------------------------------------------------------------
Tot Rx Packets : 8379                   Tot Tx Packets : 8528
Rx Hellos      : 8225                   Tx Hellos      : 8368
Rx DBDs        : 6                      Tx DBDs        : 12
Rx LSRs        : 2                      Tx LSRs        : 1
Rx LSUs        : 55                     Tx LSUs        : 95
Rx LS Acks     : 91                     Tx LS Acks     : 52
Retransmits    : 2                      Discards       : 0
Bad Networks   : 0                      Bad Virt Links : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Bad Versions   : 0
-------------------------------------------------------------------------------
At time t = 3 sec (Mode: Absolute)
-------------------------------------------------------------------------------
Tot Rx Packets : 8379                   Tot Tx Packets : 8528
Rx Hellos      : 8225                   Tx Hellos      : 8368
Rx DBDs        : 6                      Tx DBDs        : 12
Rx LSRs        : 2                      Tx LSRs        : 1
Rx LSUs        : 55                     Tx LSUs        : 95
Rx LS Acks     : 91                     Tx LS Acks     : 52
Retransmits    : 2                      Discards       : 0
Bad Networks   : 0                      Bad Virt Links : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Bad Versions   : 0
-------------------------------------------------------------------------------
At time t = 6 sec (Mode: Absolute)
-------------------------------------------------------------------------------
Tot Rx Packets : 8380                   Tot Tx Packets : 8529
Rx Hellos      : 8226                   Tx Hellos      : 8369
Rx DBDs        : 6                      Tx DBDs        : 12
Rx LSRs        : 2                      Tx LSRs        : 1
Rx LSUs        : 55                     Tx LSUs        : 95
Rx LS Acks     : 91                     Tx LS Acks     : 52
Retransmits    : 2                      Discards       : 0
Bad Networks   : 0                      Bad Virt Links : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Bad Versions   : 0
-------------------------------------------------------------------------------
At time t = 9 sec (Mode: Absolute)
-------------------------------------------------------------------------------
Tot Rx Packets : 8380                   Tot Tx Packets : 8529
Rx Hellos      : 8226                   Tx Hellos      : 8369
Rx DBDs        : 6                      Tx DBDs        : 12
Rx LSRs        : 2                      Tx LSRs        : 1
Rx LSUs        : 55                     Tx LSUs        : 95
Rx LS Acks     : 91                     Tx LS Acks     : 52
Retransmits    : 2                      Discards       : 0
Bad Networks   : 0                      Bad Virt Links : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Bad Versions   : 0
===============================================================================
A:ALA-12>monitor>router>ospf# 


A:ALA-12>monitor>router>ospf# interface to-104 interval 3 repeat 3 rate
===============================================================================
Monitor statistics for OSPF Interface "to-104"
===============================================================================
At time t = 0 sec (Base Statistics)
-------------------------------------------------------------------------------
Tot Rx Packets : 8381                   Tot Tx Packets : 8530
Rx Hellos      : 8227                   Tx Hellos      : 8370
Rx DBDs        : 6                      Tx DBDs        : 12
Rx LSRs        : 2                      Tx LSRs        : 1
Rx LSUs        : 55                     Tx LSUs        : 95
Rx LS Acks     : 91                     Tx LS Acks     : 52
Retransmits    : 2                      Discards       : 0
Bad Networks   : 0                      Bad Virt Links : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Bad Versions   : 0
-------------------------------------------------------------------------------
At time t = 3 sec (Mode: Rate)
-------------------------------------------------------------------------------
Tot Rx Packets : 0                      Tot Tx Packets : 0
Rx Hellos      : 0                      Tx Hellos      : 0
Rx DBDs        : 0                      Tx DBDs        : 0
Rx LSRs        : 0                      Tx LSRs        : 0
Rx LSUs        : 0                      Tx LSUs        : 0
Rx LS Acks     : 0                      Tx LS Acks     : 0
Retransmits    : 0                      Discards       : 0
Bad Networks   : 0                      Bad Virt Links : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Bad Versions   : 0
-------------------------------------------------------------------------------
At time t = 6 sec (Mode: Rate)
-------------------------------------------------------------------------------
Tot Rx Packets : 0                      Tot Tx Packets : 0
Rx Hellos      : 0                      Tx Hellos      : 0
Rx DBDs        : 0                      Tx DBDs        : 0
Rx LSRs        : 0                      Tx LSRs        : 0
Rx LSUs        : 0                      Tx LSUs        : 0
Rx LS Acks     : 0                      Tx LS Acks     : 0
Retransmits    : 0                      Discards       : 0
Bad Networks   : 0                      Bad Virt Links : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Bad Versions   : 0
-------------------------------------------------------------------------------
At time t = 9 sec (Mode: Rate)
-------------------------------------------------------------------------------
Tot Rx Packets : 0                      Tot Tx Packets : 0
Rx Hellos      : 0                      Tx Hellos      : 0
Rx DBDs        : 0                      Tx DBDs        : 0
Rx LSRs        : 0                      Tx LSRs        : 0
Rx LSUs        : 0                      Tx LSUs        : 0
Rx LS Acks     : 0                      Tx LS Acks     : 0
Retransmits    : 0                      Discards       : 0
Bad Networks   : 0                      Bad Virt Links : 0
Bad Areas      : 0                      Bad Dest Addrs : 0
Bad Auth Types : 0                      Auth Failures  : 0
Bad Neighbors  : 0                      Bad Pkt Types  : 0
Bad Lengths    : 0                      Bad Hello Int. : 0
Bad Dead Int.  : 0                      Bad Options    : 0
Bad Versions   : 0
===============================================================================
A:ALA-12>monitor>router>ospf#
neighbor
Syntax

neighbor ip-address [ip-address...(up to 5 max)] [interval seconds] [repeat repeat] [absolute | rate]

neighbor router-id ip-int-name [interval seconds] [repeat repeat] [absolute | rate] area area-id

Context

monitor>router>ospf

monitor>router>ospf3

Description

This command displays statistical OSPF or OSPFv3 neighbor information at the configured interval until the configured count is reached.

The first screen displays the current statistics related to the specified OSPF or OSPFv3 neighbors. The subsequent statistical information listed for each interval is displayed as a delta to the previous display.

When the keyword rate is specified, the rate-per-second for each statistic is displayed instead of the delta.

Monitor commands are similar to show commands but only statistical information displays. Monitor commands display the selected statistics according to the configured number of times at the interval specified.

Parameters
ip-address

(OSPF): the IP address to display information for entries received from the specified OSPF neighbor. Up to five IP addresses can be specified.

Values

a.b.c.d

router-id

(OSPFv3): the 32-bit router ID

Values

a.b.c.d

ip-int-name

(OSPFv3): the IP interface name

seconds

configures the interval for each display, in seconds

Values

3 to 60

Default

10

repeat

configures the number of times the command is repeated

Values

1 to 999

Default

10

absolute

displays raw statistics, without processing. No calculations are performed on the delta or rate statistics.

rate

displays rate-per-second for each statistic instead of the delta

area-id

(OSPFv3): the OSPFv3 area ID, expressed in dotted-decimal notation or as a 32-bit decimal integer

Values

ip-address | 0 to 4294967295

Output

The following output is an example of OSPF neighbor information.

Output example 
A:ALA-12>monitor>router# ospf neighbor 10.0.0.104 interval 3 repeat 3 absolute
===============================================================================
Monitor statistics for OSPF Neighbor 10.0.0.104
===============================================================================
At time t = 0 sec (Base Statistics)
-------------------------------------------------------------------------------
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
-------------------------------------------------------------------------------
At time t = 3 sec (Mode: Absolute)
-------------------------------------------------------------------------------
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
-------------------------------------------------------------------------------
At time t = 6 sec (Mode: Absolute)
-------------------------------------------------------------------------------
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
-------------------------------------------------------------------------------
At time t = 9 sec (Mode: Absolute)
-------------------------------------------------------------------------------
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
=======================================================================
A:ALA-12>monitor>router# 


A:ALA-12>monitor>router# ospf neighbor 10.0.0.104 interval 3 repeat 3 absolute
===============================================================================
Monitor statistics for OSPF Neighbor 10.0.0.104
===============================================================================
-------------------------------------------------------------------------------
At time t = 0 sec (Base Statistics)
-------------------------------------------------------------------------------
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
-------------------------------------------------------------------------------
At time t = 3 sec (Mode: Rate)
-------------------------------------------------------------------------------
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
-------------------------------------------------------------------------------
At time t = 6 sec (Mode: Rate)
-------------------------------------------------------------------------------
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
-------------------------------------------------------------------------------
At time t = 9 sec (Mode: Rate)
-------------------------------------------------------------------------------
Bad Nbr States   : 0                    LSA Inst fails   : 0
Bad Seq Nums     : 0                    Bad MTUs         : 0
Bad Packets      : 0                    LSA not in LSDB  : 0
Option Mismatches: 0                    Nbr Duplicates   : 0
===============================================================================
A:ALA-12>monitor>router#
virtual-link
Syntax

virtual-link nbr-rtr-id area area-id [interval seconds] [repeat repeat] [absolute | rate]

Context

monitor>router>ospf

monitor>router>ospf3

Description

This command displays statistical OSPF or OSPFv3 virtual link information at the configured interval until the configured count is reached.

The first screen displays the current statistics related to the specified neighbors. The subsequent statistical information listed for each interval is displayed as a delta to the previous display.

When the keyword rate is specified, the rate-per-second for each statistic is displayed instead of the delta.

Monitor commands are similar to show commands but only statistical information displays. Monitor commands display the selected statistics according to the configured number of times at the interval specified.

Parameters
nbr-rtr-id

the IP address to uniquely identify a neighboring router in the autonomous system

Values

a.b.c.d

area-id

the OSPF area ID, expressed in dotted-decimal notation or as a 32-bit decimal integer

Values

ip-address | 0 to 4294967295

seconds

configures the interval for each display, in seconds

Values

3 to 60

Default

10

repeat

configures how many times the command is repeated

Values

1 to 999

Default

10

absolute

displays raw statistics, without processing. No calculations are performed on the delta or rate statistics.

rate

displays rate-per-second for each statistic instead of the delta

virtual-neighbor
Syntax

virtual-neighbor nbr-rtr-id area area-id [interval seconds] [repeat repeat] [absolute | rate]

virtual-neighbor nbr-rtr-id transit-area transit-area [interval seconds] [repeat repeat] [absolute | rate]

Context

monitor>router>ospf

monitor>router>ospf3

Description

This command displays statistical OSPF or OSPFv3 virtual neighbor information at the configured interval until the configured count is reached.

The first screen displays the current statistics related to the specified OSPF or OSPFv3 virtual neighbor router. The subsequent statistical information listed for each interval is displayed as a delta to the previous display.

When the keyword rate is specified, the rate-per-second for each statistic is displayed instead of the delta.

Monitor commands are similar to show commands but only statistical information displays. Monitor commands display the selected statistics according to the configured number of times at the interval specified.

Parameters
nbr-rtr-id

the IP address to uniquely identify a neighboring router in the autonomous system

Values

a.b.c.d

area-id

(OSPF): the OSPF area ID, expressed in dotted-decimal notation or as a 32-bit decimal integer

Values

ip-address | 0 to 4294967295

transit-area

(OSPFv3): the OSPFv3 transit area ID, expressed in dotted-decimal notation or as a 32-bit decimal integer

Values

ip-address | 0 to 4294967295

seconds

configures the interval for each display, in seconds

Values

3 to 60

Default

10

repeat

configures how many times the command is repeated

Values

1 to 999

Default

10

absolute

displays raw statistics, without processing. No calculations are performed on the delta or rate statistics.

rate

displays rate-per-second for each statistic instead of the delta

Debug commands

ospf
Syntax

ospf

Context

debug>router

Description

This command enables the context for OSPF debugging purposes.

ospf3
Syntax

ospf3

Context

debug>router

Description

This command enables the context for OSPFv3 debugging purposes.

area
Syntax

area [area-id]

no area

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for an OSPF area.

Parameters
area-id

the OSPF area ID expressed in dotted-decimal notation or as a 32-bit decimal integer

area-range
Syntax

area-range [ip-address]

no area-range

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for an OSPF area range.

Parameters
ip-address

the IP address for the range used by the ABR to advertise into another area

cspf
Syntax

cspf [ip-address]

no cspf

Context

debug>router>ospf

Description

This command enables or disables debugging for an OSPF constraint-based shortest path first (CSPF).

Parameters
ip-address

the IP address for the range used for CSPF

interface
Syntax

interface [ip-int-name | ip-address]

no interface

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for an OSPF interface.

Parameters
ip-int-name

the IP interface name. An interface name cannot be in the form of an IP address. Interface names can be any string up to 32 characters long composed of printable, 7-bit ASCII characters. If the string contains special characters (such as #, $, or spaces), the entire string must be enclosed within double quotes.

ip-address

the interface’s IP address

leak
Syntax

leak [ip-address]

no leak

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for OSPF leaks.

Parameters
ip-address

the IP address to debug OSPF leaks

lsdb
Syntax

lsdb [type] [ls-id] [adv-rtr-id] [area area-id]

no lsdb

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for an OSPF link-state database.

Parameters
type

the OSPF link-state database type

Values

router, network, summary, asbr, extern, nssa

ls-id

an LSA type-specific field containing either a router ID or an IP address. It identifies the piece of the routing domain being described by the advertisement.

adv-rtr-id

the router identifier of the router advertising the LSA

area-id

the OSPF area ID expressed in dotted-decimal notation or as a 32-bit decimal integer

misc
Syntax

[no] misc

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for miscellaneous OSPF events.

neighbor
Syntax

neighbor [ip-int-name | router-id]

no neighbor

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for an OSPF neighbor.

Parameters
ip-int-name

the neighbor interface name

router-id

neighbor information for the neighbor identified by the specified router ID

nssa-range
Syntax

nssa-range [ip-address]

no nssa-range

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for an NSSA range.

Parameters
ip-address

the IP address range to debug

packet
Syntax

packet [packet-type] [ip-address]

no packet

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for OSPF packets.

Parameters
packet-type

the OSPF packet type to debug

Values

hello, dbdescr, lsrequest, lsupdate, lsack

ip-address

the IP address to debug

rsvp-shortcut
Syntax

rsvp-shortcut [ip-address]

no rsvp-shortcut

Context

debug>router>ospf

Description

This command enables or disables debugging for RSVP-TE LSPs that are used as shortcuts.

Parameters
ip-address

the IP address to debug

rtm
Syntax

rtm [ip-address]

no rtm

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for the OSPF routing table manager.

Parameters
ip-address

the IP address to debug

sham-neighbor
Syntax

sham-neighbor [ip-address]

no sham-neighbor

Context

debug>router>ospf

Description

This command enables or disables debugging for an OSPF sham-link neighbor.

Parameters
ip-address

the IP address to debug

spf
Syntax

spf [type] [dest-addr]

no spf

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for OSPF SPF. Information regarding overall SPF start and stop times are shown. To see detailed information regarding the SPF calculation of a given route, the route must be specified as an optional argument.

Parameters
type

the area to debug

Values

intra-area, inter-area, external

dest-addr

the destination IP address to debug

virtual-neighbor
Syntax

virtual-neighbor [ip-address]

no virtual-neighbor

Context

debug>router>ospf

debug>router>ospf3

Description

This command enables or disables debugging for an OSPF virtual neighbor.

Parameters
ip-address

the IP address of the virtual neighbor