Virtual Private LAN Service

In a Layer 2 environment, subscribers or customers connected to SAPs A or B can create a denial of service attack by sending packets sourcing the gateway MAC address. This moves the learned gateway MAC from the uplink SDP/SAP to the subscriber’s or customer’s SAP causing all communication to the gateway to be disrupted. If local content is attached to the same VPLS (D), a similar attack can be launched against it. Communication between subscribers or customers is also disallowed but split horizon is not sufficient in the topology shown in MAC learning protection.

The 7450 ESS, 7750 SR, and 7950 XRS routers enable MAC learning protection capability for SAPs and SDPs. With this mechanism, forwarding and learning rules apply to the non-protected SAPs. Assume hosts H1, H2, and H3 (MAC learning protection) are non-protected while IES interfaces G and H are protected. When a frame arrives at a protected SAP/SDP, the MAC is learned as usual. When a frame arrives from a non-protected SAP or SDP, the frame must be dropped if the source MAC address is protected and the MAC address is not relearned. The system allows only packets with a protected MAC destination address.

The system can be configured statically. The addresses of all protected MACs are configured. Only the IP address can be included and use a dynamic mechanism to resolve the MAC address (cpe-ping). All protected MACs in all VPLS instances in the network must be configured.

To eliminate the ability of a subscriber or customer to cause a DoS attack, the node restricts the learning of protected MAC addresses based on a statically defined list. Also, the destination MAC address is checked against the protected MAC list to verify that a packet entering a restricted SAP has a protected MAC as a destination.

The IEEE 802.1ad-2005 standard allows drop eligibility to be conveyed separately from priority in Service VLAN TAGs (S-TAGs) so that all of the previously introduced traffic types can be marked as drop eligible. The S-TAG has a new format where the priority and discard eligibility parameters are conveyed in the 3-bit Priority Code Point (PCP) field and, respectively, in the DE bit (DE bit in the 802.1ad S-TAG).

The DE bit allows the S-TAG to convey eight forwarding classes/distinct emission priorities, each with a drop eligible indication.

When the DE bit is set to 0 (DE=FALSE), the related packet is not discarded eligible. This is the case for the packets that are within the CIR limits and must be prioritized in case of congestion. If the DEI is not used or backwards compliance is required, the DE bit should be set to zero on transmission and ignored on reception.

When the DE bit is set to 1 (DE=TRUE), the related packet is discarded eligible. This is the case for the packets that are sent above the CIR limit (but below the PIR). In case of congestion, these packets are the first ones to be dropped.

Source MAC addresses are learned in a VPLS service by default with an entry allocated in the FDB for each address on all line cards. Therefore, all MAC addresses are considered to be global. This operation can be modified so that the line card allocation of some MAC addresses is selective, based on where the service has a configured object.

An example of the advantage of selective MAC address learning is for services to benefit from the higher MAC address scale of some line cards (particularly for network interfaces used by mesh or spoke-SDPs, EVPN-VXLAN tunnels, and EVPN-MPLS destinations) while using lower MAC address scale cards for the SAPs.

Selective MAC addresses are those learned locally and dynamically in the datapath (displayed in the show output with type ‟L”) or by EVPN (displayed in the show output with type ‟Evpn”, excluding those with the sticky bit set, which are displayed with type ‟EvpnS”). An exception is when a MAC address configured as a conditional static MAC address is learned dynamically on an object other than its monitored object; this can be displayed with type ‟L” or ‟Evpn” but is learned as global because of the conditional static MAC configuration.

Selective MAC addresses have FDB entries allocated on line cards where the service has a configured object. When a MAC address is learned, it is allocated an FDB entry on all line cards on which the service has a SAP configured (for LAG or Ethernet tunnel SAPs, the MAC address is allocated an FDB entry on all line cards on which that LAG or Ethernet tunnel has configured ports) and on all line cards that have a network interface port if the service is configured with VXLAN, EVPN-MPLS, or a mesh or spoke-SDP.

When using selective learning in an I-VPLS service, the learned C-MACs are allocated FDB entries on all the line cards where the I-VPLS service has a configured object and on the line cards on which the associated B-VPLS has a configured object. When using selective learning in a VPLS service with allow-ip-intf-bind configured (for it to become an R-VPLS), FDB entries are allocated on all line cards on which there is an IES or VPRN interface.

If a new configured object is added to a service and there are sufficient MAC FDB resources available on the new line cards, the selective MAC addresses present in the service are allocated on the new line cards. Otherwise, if any of the selective MAC addresses currently learned in the service cannot be allocated an FDB entry on the new line cards, those MAC addresses are deleted from all line cards. Such a deletion increments the FailedMacCmplxMapUpdts statistic displayed in the tools dump service vpls-fdb-stats output.

When the set of configured objects changes for a service using selective learning, the system must reallocate its FDB entries accordingly, which can cause FDB entry ‟allocate” or ‟free” operations to become pending temporarily. The pending operations can be displayed using the tools dump service id fdb command.

When a global MAC address is to be learned, there must be a free FDB entry in the service and system FDBs and on all line cards in the system for it to be accepted. When a selective MAC address is to be learned, there must be a free FDB entry in the service and system FDBs and on all line cards where the service has a configured object for it to be accepted.

To demonstrate the selective MAC address learning logic, consider the following:

• a system has three line cards: 1, 2, and 3

• two VPLS services are configured on the system:

  • VPLS 1 having learned MAC addresses M1, M2, and M3 and has configured SAPs 1/1/1 and 2/1/1

  • VPLS 2 having learned MAC addresses M4, M5, and M6 and has configured SAPs 2/1/2 and 3/1/1

This is shown in MAC address learning logic example .

MAC FDB entry allocation: global versus selective shows the FDB entry allocation when the MAC addresses are global and when they are selective. Notice that in the selective case, all MAC addresses are allocated FDB entries on line card 2, but line card 1 and 3 only have FDB entries allocated for services VPLS 1 and VPLS 2, respectively.

Selective MAC address learning can be enabled as follows within any VPLS service, except for B-VPLS and R-VPLS services:

configure
        service 
            vpls <service-id> create
                [no] selective-learned-fdb

Enabling selective MAC address learning has no effect on single line card systems.

When selective learning is enabled or disabled in a VPLS service, the system may need to reallocate FDB entries; this can cause temporary pending FDB entry allocate or free operations. The pending operations can be displayed using the tools dump service id fdb command.

The system FDB table size is configurable as follows:

configure
        service
            system
                fdb-table-size table-size

where table-size can have values in the range from 255999 to 2047999 (2000k).

The default, minimum, and maximum values for the table size are dependent on the chassis type. To support more than 500k MAC addresses, the CPMs provisioned in the system must have at least 16 GB memory. The maximum system FDB table size also limits the maximum FDB table size of any card within the system.

The actual achievable maximum number of MAC addresses depends on the MAC address scale supported by the active cards and whether selective learning is enabled.

If an attempt is made to configure the system FDB table size such that:

• the new size is greater than or equal to the current number of allocated FDB entries, the command succeeds and the new system FDB table size is used

• the new size is less than the number of allocated FDB entries, the command fails with an error message. In this case, the user is expected to reduce the current FDB usage (for example, by deleting statically configured MAC addresses, shutting down EVPN, clearing learned MACs, and so on) to lower the number of allocated MAC addresses in the FDB so that it does not exceed the system FDB table size being configured.

The logic when attempting a rollback is similar; however, when rolling back to a configuration where the system FDB table size is smaller than the current system FDB table size, the system flushes all learned MAC addresses (by performing a shutdown then no shutdown in all VPLS services) to allow the rollback to continue.

The system FDB table size can be larger than some of the line card FDB sizes, resulting in the possibility that the current number of allocated global MAC addresses is larger than the maximum FDB size supported on some line cards. When a new line card is provisioned, the system checks whether the line card's FDB can accommodate all of the currently allocated global MAC addresses. If it can, then the provisioning succeeds; if it cannot, then the provisioning fails and an error is reported. If the provisioning fails, the number of global MACs allocated must be reduced in the system to a number that the new line card can accommodate, then the card-type must be reprovisioned.

The following MAC table management features are available for each instance of a SAP or spoke-SDP within a particular VPLS service instance.

High and low watermark alarms give warning when the system MAC FDB usage is high. An alarm is generated when the number of FDB entries allocated in the system FDB reaches 95% of the total system FDB table size and is cleared when it reduces to 90% of the system FDB table size. These percentages are not configurable.

High and low watermark alarms give warning when a line card's MAC FDB usage is high. An alarm is generated when the number of FDB entries allocated in a line card FDB reaches 95% of its maximum FDB table size and is cleared when it reduces to 90% of its maximum FDB table size. These percentages are not configurable.

The size of the VPLS FDB can be configured with a low watermark and a high watermark, expressed as a percentage of the total FDB size limit. If the actual FDB size grows above the configured high watermark percentage, an alarm is generated. If the FDB size falls below the configured low watermark percentage, the alarm is cleared by the system.

Like a Layer 2 switch, learned MACs within a VPLS instance can be aged out if no packets are sourced from the MAC address for a specified period of time (the aging time). In each VPLS service instance, there are independent aging timers for locally learned MAC and remotely learned MAC entries in the FDB. A local MAC address is a MAC address associated with a SAP because it ingressed on a SAP. A remote MAC address is a MAC address received by an SDP from another router for the VPLS instance.

The local-age timer for the VPLS instance specifies the aging time for locally learned MAC addresses, and the remote-age timer specifies the aging time for remotely learned MAC addresses.

In general, the remote-age timer is set to a longer period than the local-age timer to reduce the amount of flooding required for unknown destination MAC addresses. The aging mechanism is considered a low priority process. In most situations, the aging out of MAC addresses happens within tens of seconds beyond the age time. However, it, can take up to two times their respective age timer to be aged out.

The MAC aging timers can be disabled, which prevents any learned MAC entries from being aged out of the FDB. When aging is disabled, it is still possible to manually delete or flush learned MAC entries.

Aging can be disabled for learned MAC addresses on a SAP or a spoke-SDP of a VPLS service instance.

When MAC learning is disabled for a service, new source MAC addresses are not entered in the VPLS FDB, whether the MAC address is local or remote. MAC learning can be disabled for individual SAPs or spoke-SDPs.

Unknown MAC discard is a feature that discards all packets that ingress the service where the destination MAC address is not in the FDB. The normal behavior is to flood these packets to all endpoints in the service.

Unknown MAC discard can be used with the disable MAC learning and disable MAC aging options to create a fixed set of MAC addresses allowed to ingress and traverse the service.

Traffic that is normally flooded throughout the VPLS can be rate limited on SAP ingress through the use of service ingress QoS policies. In a service ingress QoS policy, individual queues can be defined per forwarding class to provide shaping of broadcast traffic, MAC multicast traffic, and unknown destination MAC traffic.

The MAC move feature is useful to protect against undetected loops in a VPLS topology as well as the presence of duplicate MACs in a VPLS service.

If two clients in the VPLS have the same MAC address, the VPLS experiences a high relearn rate for the MAC. When MAC move is enabled, the 7450 ESS, 7750 SR, or 7950 XRS shuts down the SAP or spoke-SDP and creates an alarm event when the threshold is exceeded.

MAC move allows sequential order port blocking. By configuration, some VPLS ports can be configured as ‟non-blockable”, which allows a simple level of control of which ports are being blocked during loop occurrence. There are two sophisticated control mechanisms that allow blocking of ports in a sequential order:

1. Configuration capabilities to group VPLS ports and to define the order in which they should be blocked

2. Criteria defining when individual groups should be blocked

For the first control mechanism, configuration CLI is extended by definition of ‟primary” and ‟secondary” ports. Per default, all VPLS ports are considered ‟tertiary” ports unless they are explicitly declared primary or secondary. The order of blocking always follows a strict order starting from tertiary to secondary, and then primary.

The definition of criteria for the second control mechanism is the number of periods during which the specified relearn rate has been exceeded. The mechanism is based on the cumulative factor for every group of ports. Tertiary VPLS ports are blocked if the relearn rate exceeds the configured threshold during one period, while secondary ports are blocked only when relearn rates are exceeded during two consecutive periods, and primary ports when exceeded during three consecutive periods. The retry timeout period must be larger than the period before blocking the highest priority port so that the retry timeout sufficiently spans across the period required to block all ports in sequence. The period before blocking the highest priority port is the cumulative factor of the highest configured port multiplied by 5 seconds (the retry timeout can be configured through the CLI).

This section provides information about the auto-learn MAC protect and restrict-protected-src discard-frame features.

VPLS solutions usually involve learning MAC addresses so that traffic can be forwarded to the correct SAP or SDP. If a MAC address is learned on the wrong SAP or SDP, traffic is redirected away from its intended destination. This could occur as a result of a misconfiguration, a problem in the network, or by a malicious source creating a DoS attack, and is applicable to any type of VPLS network; for example, mobile backhaul or residential service delivery networks. The auto-learn MAC protect feature safeguards against the possibility of MAC addresses being learned on the wrong SAP or SDP.

This feature automatically protects source MAC addresses that have been learned on a SAP or SDP (spoke or mesh) and prevents frames with the same protected source MAC address from entering a different SAP or SDP (spoke or mesh).

This solution has low operational complexity and is complementary to features such as MAC move and MAC pinning, but has the advantage that MAC moves are not seen. If a MAC is initially learned on the wrong SAP or SDP, the operator can clear the MAC from the MAC FDB so it can be relearned on the correct SAP or SDP.

Two separate commands provide the configuration flexibility of separating the identification (learning) function from the application of the restriction (discard).

The auto-learn-mac-protect and restrict-protected-src commands allow the following functions:

• the ability to enable the automatic protection of a learned MAC using the auto-learn-mac-protect command under a SAP, or spoke or mesh SDP, or SHG context

• the ability to discard frames associated with automatically protected MACs instead of shutting down the entire SAP or SDP, as with the restrict-protected-src feature. This is enabled using a restrict-protected-src discard-frame command in the SAP, or spoke or mesh SDP, or split horizon group (SHG) context. An optimized alarm mechanism is used to generate alarms related to these discards. The frequency of alarm generation is fixed to be, at most, one alarm per MAC address per forwarding complex per 10 minutes in a VPLS service.

If the auto-learn-mac-protect or restrict-protected-src discard-frame feature is configured under an SHG, the operation applies only to SAPs in the SHG, not to spoke-SDPs in the SHG. If required, these parameters can also be enabled explicitly under specific SAPs or spoke-SDPs within the SHG.

Applying or removing auto-learn-mac-protect or restrict-protected-src discard-frame to or from a SAP, spoke or mesh SDP, or SHG, clears the MACs on the related objects. For the SHG, this results in clearing the MACs only on the SAPs within the SHG.

The use of restrict-protected-src discard-frame and both the restrict-protected-src [alarm-only] command and with the configuration of manually protected MAC addresses, using the mac-protect command, within a specified VPLS are mutually exclusive.

The following rules apply to the state changes of protected MACs:

• Automatically learned protected MACs are subject to normal removal, aging (unless disabled), and flushing, at which time the associated entries are removed from the FDB.

• Automatically learned protected MACs can move from their learned SAP or spoke or mesh SDP only if they enter a SAP or spoke or mesh SDP without the restrict-protected-src command enabled.

If a MAC address legitimately moves between SAPs or spoke or mesh SDPs after it is automatically protected on a specified SAP or spoke or mesh SDP (thereby causing discards when received on the new SAP or spoke or mesh SDP), the operator must manually clear the MAC from the FDB for it to be learned in the new location.

MAC addresses that are manually created (using static-mac, static-host with a MAC address specified, or oam mac-populate) are not protected even if they are configured on a SAP or spoke or mesh SDP that has the auto-learn-mac-protect command enabled on it. Also, the MAC address associated with an R-VPLS IP interface is protected within its VPLS service such that frames received with this MAC address as the source address are discarded (this is not based on the auto-learn MAC protect function). However, VRRP MAC addresses associated with an R-VPLS IP interface are not protected, either in this way or using the auto-learn MAC protect function.

MAC addresses that are dynamically created (learned, using static-host with no MAC address specified, or lease-populate) are protected when the MAC address is learned on a SAP or spoke or mesh SDP that has the auto-learn-mac-protect command enabled on it.

The actions of the following features are performed in the order listed.

1. Restrict protected SRC

2. MAC pinning

3. MAC move

Per VPLS instance, a preferred STP variant can be configured. The STP variants supported are:

• rstp

  Rapid Spanning Tree Protocol (RSTP) compliant with IEEE 802.1D-2004 - default mode

• dot1w

  Compliant with IEEE 802.1w

• comp-dot1w

  Operation as in RSTP but backwards compatible with IEEE 802.1w (this mode allows interoperability with some MTU types)

• mstp

  Compliant with the Multiple Spanning Tree Protocol specified in IEEE 802.1Q-REV/D5.0-09/2005. This mode of operation is only supported in a Management VPLS (MVPLS).

While the 7450 ESS, 7750 SR, or 7950 XRS initially use the mode configured for the VPLS, it dynamically falls back (on a per-SAP basis) to STP (IEEE 802.1D-1998) based on the detection of a BPDU of a different format. A trap or log entry is generated for every change in spanning tree variant.

Some older 802.1w compliant RSTP implementations may have problems with some of the features added in the 802.1D-2004 standard. Interworking with these older systems is improved with the comp-dot1w mode. The differences between the RSTP mode and the comp-dot1w mode are as follows.

• The RSTP mode implements the improved convergence over shared media feature; for example, RSTP transitions from discarding to forwarding in 4 seconds when operating over shared media. The comp-dot1w mode does not implement this 802.1D-2004 improvement and transitions conform to 802.1w in 30 seconds (both modes implement fast convergence over point-to-point links).

• In the RSTP mode, the transmitted BPDUs contain the port's designated priority vector (DPV) (conforms to 802.1D-2004). Older implementations may be confused by the DPV in a BPDU and may fail to recognize an agreement BPDU correctly. This would result in a slow transition to a forwarding state (30 seconds). For this reason, in the comp-dot1w mode, these BPDUs contain the port's port priority vector (conforms to 802.1w).

The 7450 ESS, 7750 SR, and 7950 XRS support two BPDU encapsulation formats, and can dynamically switch between the following supported formats (on a per-SAP basis):

• IEEE 802.1D STP

• Cisco PVST

Multiple Spanning Tree Protocol (MSTP) extends the concept of the IEEE 802.1w Rapid Spanning Tree Protocol (RSTP) by allowing grouping and associating VLANs to Multiple Spanning Tree Instances (MSTI). Each MSTI can have its own topology, which provides architecture enabling load balancing by providing multiple forwarding paths. At the same time, the number of STP instances running in the network is significantly reduced as compared to Per VLAN STP (PVST) mode of operation. Network fault tolerance is also improved because a failure in one instance (forwarding path) does not affect other instances.

The Nokia implementation of M-VPLS is used to group different VPLS instances under one RSTP instance. Introducing MSTP into the M-VPLS allows the following:

• interoperation with traditional Layer 2 switches in an access network

• provides an effective solution for dual-homing of many business Layer 2 VPNs into a provider network

MSTP runs in a M-VPLS context and can control SAPs from source VPLS instances. QinQ SAPs are supported. The outer tag is considered by MSTP as part of VLAN range control.

Provider MSTP is specified in IEEE-802.1ad-2005. It uses a provider bridge group address instead of a regular bridge group address used by STP, RSTP, and MSTP BPDUs. This allows for implicit separation of source and provider control planes.

The 802.1ad access network sends PBB PE P-MSTP BPDUs using the specified MAC address and also works over QinQ interfaces. P-MSTP mode is used in PBBN for core resiliency and loop avoidance.

Similar to regular MSTP, the STP mode (for example, PMSTP) is only supported in VPLS services where the m-VPLS flag is configured.

To interconnect PE devices across the backbone, service tunnels (SDPs) are used. These service tunnels are shared among multiple VPLS instances. The Nokia implementation of the STP incorporates some enhancements to make the operational characteristics of VPLS more effective. The implementation of STP on the router is modified to guarantee that service tunnels are not blocked in any circumstance without imposing artificial restrictions on the placement of the root bridge within the network. The modifications introduced are fully compliant with the 802.1D-2004 STP specification.

When running MSTP, spoke-SDPs cannot be configured. Also, ensure that all bridges connected by mesh SDPs are in the same region. If not, the mesh is prevented from becoming active (trap is generated).

To achieve this, all mesh SDPs are dynamically configured as either root ports or designated ports. The PE devices participating in each VPLS mesh determine (using the root path cost learned as part of the normal protocol exchange) which of the 7450 ESS, 7750 SR, or 7950 XRS devices is closest to the root of the network. This PE device is internally designated as the primary bridge for the VPLS mesh. As a result of this, all network ports on the primary bridges are assigned the designated port role and therefore remain in the forwarding state.

The second part of the solution ensures that the remaining PE devices participating in the STP instance see the SDP ports as a lower-cost path to the root instead of a path that is external to the mesh. Internal to the PE nodes participating in the mesh, the SDPs are treated as zero cost paths toward the primary bridge. As a consequence, the paths through the mesh are seen as lower cost than any alternative and the PE node designates the network port as the root port. This ensures that network ports always remain in forwarding state.

A combination of the preceding features ensure that network ports are never blocked and maintain interoperability with bridges external to the mesh that are running STP instances.

When two or more meshed VPLS instances are interconnected by redundant spoke-SDPs (as shown in H-VPLS with spoke redundancy), a loop in the topology results. To remove such a loop from the topology, STP can be run over the SDPs (links) that form the loop, such that one of the SDPs is blocked. As running STP in each and every VPLS in this topology is not efficient, the node includes functionality that can associate a number of VPLSs with a single STP instance running over the redundant-SDPs. Node redundancy is therefore achieved by running STP in one VPLS, and applying the conclusions of this STP to the other VPLS services. The VPLS instance running STP is referred to as the ‟management VPLS” or M-VPLS.

In the case of a failure of the active node, STP on the management VPLS in the standby node changes the link states from disabled to active. The standby node then broadcasts a MAC flush LDP control message in each of the protected VPLS instances, so that the address of the newly active node can be re-learned by all PEs in the VPLS.

It is possible to configure two management VPLS services, where both VPLS services have different active spokes (this is achieved by changing the path cost in STP). By associating different user VPLSs with the two management VPLS services, load balancing across the spokes can be achieved.

This feature provides the ability to have a node deployed as MTUs (Multi-tenant Unit Switches) to be multi-homed for VPLS to multiple routers deployed as PEs without requiring the use of M-VPLS.

In the configuration example shown in H-VPLS with spoke redundancy, the MTUs have spoke-SDPs to two PE devices. One is designated as the primary and one as the secondary spoke-SDP. This is based on a precedence value associated with each spoke.

The secondary spoke is in a blocking state (both on receive and transmit) as long as the primary spoke is available. When the primary spoke becomes unavailable (because of the link failure, PEs failure, and so on), the MTUs immediately switch traffic to the backup spoke and start receiving traffic from the standby spoke. Optional revertive operation (with configurable switch-back delay) is supported. Forced manual switchover is also supported.

To speed up the convergence time during a switchover, MAC flush is configured. The MTUs generates a MAC flush message over the newly unblocked spoke when a spoke change occurs. As a result, the PEs receiving the MAC flush flushes all MACs associated with the impacted VPLS service instance and forward the MAC flush to the other PEs in the VPLS network if propagate-mac-flush is enabled.

Inter-domain VPLS refers to a VPLS deployment where sites may be located in different domains. An example of inter-domain deployment can be where different metro domains are interconnected over a Wide Area Network (Metro1-WAN-Metro2) or where sites are located in different autonomous systems (AS1-ASBRs-AS2).

Multichassis endpoint (MC-EP) provides an alternate solution that does not require RSTP at the gateway VPLS PEs while still using pseudowires to interconnect the VPLS instances located in the two domains. It is supported in both VPLS and PBB-VPLS on the B-VPLS side.

MC-EP expands the single chassis endpoint based on active/standby pseudowires for VPLS, shown in HVPLS resiliency based on AS pseudowires.

The active/standby pseudowire solution is appropriate for the scenario when only one VPLS PE (MTUs) needs to be dual-homed to two core PEs (PE1 and PE2). When multiple VPLS domains need to be interconnected, the above solution provides a single point of failure at the MTU-s. The example shown in Multichassis pseudowire endpoint for VPLS can be used.

The two gateway pairs, PE3-PE3’ and PE1-PE2, are interconnected using a full mesh of four pseudowires out of which only one pseudowire is active at any time.

The concept of pseudowire endpoint for VPLS provides multi-chassis resiliency controlled by the MC-EP pair, PE3-PE3’ in this example. This scenario, referred to as multi-chassis pseudowire endpoint for VPLS, provides a way to group pseudowires distributed between PE3 and PE3 chassis in a virtual endpoint that can be mapped to a VPLS instance.

The MC-EP inter-chassis protocol is used to ensure configuration and status synchronization of the pseudowires that belong to the same MC-EP group on PE3 and PE3. Based on the information received from the peer shelf and the local configuration, the master shelf decides on which pseudowire becomes active.

The MC-EP solution is built around the following components:

• Multichassis protocol used to perform the following functions:

  • Selection of master chassis.

  • Synchronization of the pseudowire configuration and status.

  • Fast detection of peer failure or communication loss between MC-EP peers using either centralized BFD, if configured, or its own keep-alive mechanism.

• T-LDP signaling of pseudowire status informs the remote PEs about the choices made by the MC-EP pair.

• Pseudowire data plane is represented by the four pseudowires inter-connecting the gateway PEs.

  • Only one of the pseudowires is activated based on the primary/secondary, preference configuration, and pseudowire status. In case of a tie, the pseudowire located on the master chassis is chosen.

  • The rest of the pseudowires are blocked locally on the MC-EP pair and on the remote PEs as long as they implement the pseudowire active/standby status.

In cases of SC-EP, there is a consistency check to ensure that the configuration of the member pseudowires is the same. For example, mac-pining, mac-limit, and ignore standby signaling must be the same. In the MC-EP case, there is no consistency check between the member endpoints located on different chassis. The user must carefully verify the configuration of the two endpoints to ensure consistency.

The following rules apply for suppress-standby-signaling and ignore-standby parameters:

• Regular MC-EP mode (non-passive) follows the suppress-standby-signaling and ignore-standby settings from the related endpoint configuration.

• For MC-EP configured in passive mode, the following settings are used, regardless of previous configuration: suppress-standby-sig and no ignore-standby-sig. It is expected that when passive mode is used at one side, the regular MC-EP side activates signaling with no suppress-stdby-sig.

• When passive mode is configured in just one of the nodes in the MC-EP peering, the other node is forced to change to passive mode. A trap is sent to the operator to signal the wrong configuration.

This section also describes how the main mechanisms used for single chassis endpoint are adapted for the MC-EP solution.

The PBB-VPLS solution can be used to improve scalability of the solution and to reduce convergence time. If PBB-VPLS is deployed starting at the edge PEs, the gateway PEs contain only B-VPLS instances. The MC-EP procedures described for regular VPLS apply.

PBB-VPLS can also be enabled just on the gateway MC-EP PEs, as shown in MC-EP with B-VPLS.

Multiple I-VPLS instances may be used to represent in the gateway PEs the customer VPLS instances using the PBB-VPLS M:1 model described in the PBB section. A backbone VPLS (B-VPLS) is used in this example to administer the resiliency for all customer VPLS instances at the domain borders. Just one MC-EP is required to be configured in the B-VPLS to address hundreds or even thousands of customer VPLS instances. If load balancing is required, multiple B-VPLS instances may be used to ensure even distribution of the customers across all the pseudowires interconnecting the two domains. In this example, four B-VPLSs are able to load share the customers across all four possible pseudowire paths.

The use of MC-EP with B-VPLS is strictly limited to cases where VPLS mesh exists on both sides of a B-VPLS. For example, active/standby pseudowires resiliency in the I-VPLS context where PE3 and PE3’ are PE-rs cannot be used because there is no way to synchronize the active/standby selection between the two domains.

For a similar reason, MC-LAG resiliency in the I-VPLS context on the gateway PEs participating in the MC-EP (PE3 and PE3’) should not be used.

For the PBB topology in MC-EP with B-VPLS, block-on-mesh-failure in the I-VPLS domain does not have any effect on the B-VPLS MC-EP side. That is because mesh failure in one I-VPLS should not affect other I-VPLSs sharing the same B-VPLS.

The scenario shown in MC-EP with B-VPLS failure scenario is used to define the blackholing problem in PBB-VPLS using MC-EP.

In the topology shown in MC-EP with B-VPLS failure scenario, PEA and PEB are regular VPLS PEs participating in the VPLS mesh deployed in the metro and WAN region, respectively. As the traffic flows between CEs with C-MAC X and C-MAC Y, the FDB entries in PEA, PE3, PE1 and PEB are installed. An LDP flush-all-but-mine message is sent from PE3 to PE2 to clear the B-VPLS FDBs. The traffic between C-MAC X and C-MAC Y is blackholed as long as the entries from the VPLS and I-VPLS FDBs along the path are not removed. This may take as long as 300 seconds, the usual aging timer used for MAC entries in a VPLS FDB.

A MAC flush is required in the I-VPLS space from PBB PEs to PEA and PEB to avoid blackholing in the regular VPLS space.

In the case of a regular VPLS, the following procedure is used:

1. PE3 sends a flush-all-from-me message toward its local blue I-VPLS mesh to PE3 and PEA when its MC-EP becomes disabled.

2. PE3 sends a flush-all-but-mine message on the active PW4 to PE2, which is then propagated by PE2 (propagate-mac-flush must be on) to PEB in the WAN I-VPLS mesh.

For consistency, a similar procedure is used for the B-VPLS case as shown in MC-EP with B-VPLS MAC flush solution.

In this example, the MC-EP activates B-VPLS PW4 because of either a link/node failure or because of an MC-EP selection re-run that affected the previously active PW1. As a result, the endpoint on PE3 containing PW1 goes down.

The following steps apply:

1. PE3 sends, in the local I-VPLS context, an LDP flush-all-from-me message (marked with F1) to PEA and to the other regular VPLS PEs, including PE3. The following command enables this behavior on a per I-VPLS basis: config>service>vpls ivpls>send-flush-on-bvpls-failure.

   As a result, PEA, PE3, and the other local VPLS PEs in the metro clear the VPLS FDB entries associated with PW to PE3.

2. PE3 clears the entries associated with PW1 and sends, in the B-VPLS context, an LDP flush-all-but-mine message (marked with F2) toward PE2 on the active PW4.

   As a result, PE2 clears the B-VPLS FDB entries not associated with PW4.

3. PE2 propagates the MAC flush-all-but-mine (marked with F3) from B-VPLS in the related I-VPLS contexts toward all participating VPLS PEs; for example, in the blue I-VPLS to PEB, PE1. It also clears all the C-MAC entries associated with I-VPLS pseudowires.

   The following command enables this behavior on a per I-VPLS basis:

   config>service>vpls ivpls>propagate-mac-flush-from-bvpls

   As a result, PEB, PE1, and the other local VPLS PEs in the WAN clear the VPLS FDB entries associated with PW to PE2.

   Note: This command does not control the propagation in the related I-VPLS of the B-VPLS LDP MAC flush containing a PBB TLV (B-MAC and ISID list).

Similar to regular VPLS, LDP signaling of the MAC flush follows the active topology; for example, no MAC flush is generated on standby pseudowires.

Other failure scenarios are addressed using the same or a subset of the above steps:

• If the pseudowire (PW2) in the same endpoint with PW1 becomes active instead of PW4, there is no MAC flush of F1 type.

• If the pseudowire (PW3) in the same endpoint becomes active instead of PW4, the same procedure applies.

For an SC/MC endpoint configured in a B-VPLS, failure/deactivation of the active pseudowire member always generates a local MAC flush of all the B-MAC associated with the pseudowire. It never generates a MAC move to the newly active pseudowire even if the endpoint stays up. That is because in SC-EP/MC-EP topology, the remote PE may be the terminating PBB PE and may not be able to reach the B-MAC of the other remote PE. Therefore, connectivity between them exists only over the regular VPLS mesh.

For the same reasons, Nokia recommends that static B-MAC not be used on SC/MC endpoints.

In the configuration shown in Dual-homed MTUs in two-tier hierarchy H-VPLS, STP is activated on the MTU and two PEs to resolve a potential loop. STP only needs to run in a single VPLS instance, and the results of the STP calculations are applied to all VPLSs on the link.

In this configuration, the scope of the STP domain is limited to MTU and PEs, while any topology change needs to be propagated in the whole VPLS domain including mesh SDPs. This is done by using so-called MAC-flush messages defined by RFC 4762. In the case of STP as an loop resolution mechanism, every TCN received in the context of an STP instance is translated into an LDP-MAC address withdrawal message (also referred to as a MAC-flush message) requesting to clear all FDB entries except the ones learned from the originating PE. Such messages are sent to all PE peers connected through SDPs (mesh and spoke) in the context of VPLS services, which are managed by the specified STP instance.

The Nokia implementation also includes alternative methods for providing a redundant access to Layer 2 services, such as MC-LAG, MC-APS, or MC-Ring. Also in this case, the topology change event needs to be propagated into the VPLS topology to provide fast convergence. The topology change propagation and its corresponding MAC flush processing in a VPLS service without STP is described in Dual-homing to a VPLS service.

This feature is used in VPLS to enhance the existing BGP MH solution by providing a block-on-group failure function similar to the block-on-mesh failure feature implemented for LDP VPLS. On the PE selected as the Designated Forwarder (DF), if the rest of the VPLS endpoints fail (pseudowire spokes/pseudowire mesh or SAPs, or both), there is no path forward for the frames sent to the MH site selected as DF. The status of the VPLS endpoints, other than the MH site, is reflected by bringing down or up the objects associated with the MH site.

Support for the feature is provided initially in VPLS and B-VPLS instance types for LDP VPLS, with or without BGP-AD and for BGP VPLS. The following objects may be placed as components of an operational group: BGP VPLS pseudowires, SAPs, spoke-pseudowire, BGP-AD pseudowires. The following objects are supported as monitoring objects: BGP MH site, individual SAP, spoke-pseudowire.

The following rules apply:

• An object can only belong to one group at a time.

• An object that is part of a group cannot monitor the status of any group.

• An object that monitors the status of a group cannot be part of any group.

• An operational group may contain any combination of member types: SAP, spoke-pseudowire, BGP-AD, or BGP VPLS pseudowires.

• An operational group may contain members from different VPLS service instances.

• Objects from different services may monitor the operational group.

• The operational group feature may coexist in parallel with the block-on-mesh failure feature, provided they are running in different VPLS instances.

Perform the following steps to enable the block-on-mesh failure feature in a VPLS scenario.

1. Identify a set of objects whose forwarding state should be considered as a whole group, and then group them under an operational group using the oper-group command.

2. Associate other existing objects (clients) with the oper-group command using the monitor-group command; its forwarding state is derived from the related operational group state.

The status of the operational group (oper-group) is dictated by the status of one or more members, according to the following rules:

• The oper-group goes down if all the objects in the oper-group go down; the oper-group comes up if at least one of the components is up.

• An object in the oper-group is considered down if it is not forwarding traffic in at least one direction. That could be because the operational state is down, or the direction is blocked through resiliency mechanisms.

• If an oper-group is configured but no members are specified, its status is considered up. As soon as the first object is configured, the status of the oper-group is dictated by the status of the provisioned members.

• For BGP-AD or BGP VPLS pseudowires associated with the oper-group (under the config>service-vpls>bgp>pw-template-binding context), the status of the oper-group is down as long as the pseudowire members are not instantiated (auto-discovered and signaled).

A configuration can be described for the case of a BGP VPLS mesh used to interconnect different customer locations. For example, if a customer edge (CE) device is dual-homed to two PEs using BGP MH, the following configuration steps apply:

1. The bgp-vpls-mesh oper-group is created.

2. The BGP VPLS mesh is added to the bgp-vpls-mesh group through the pseudowire template used to create the BGP VPLS mesh.

3. The BGP MH site defined for the access endpoint is associated with the bgp-vpls-mesh group; its status from now on is influenced by the status of the BGP VPLS mesh.

service>oper-group bgp-vpls-mesh-1 create
service>vpls>bgp>pw-template-binding> oper-group bgp-vpls-mesh-1
service>vpls>site> monitor-group bgp-vpls-mesh-1

The following figure shows a dual-homed connection to VPLS service (PE-A, PE-B, PE-C, PE-D) and operation in case of link failure (between PE-C and L2-B). Upon detection of a link failure, PE-C sends MAC-address-withdraw messages, which indicate to all LDP peers that they should flush all MAC addresses learned from PE-C. This leads to a broadcasting of packets addressing affected hosts and re-learning in case an alternative route exists.

The message described here is different from the message described in RFC 4762, Virtual Private LAN Services Using LDP Signaling. The difference is in the interpretation and action performed in the receiving PE. According to the standard definition, upon receipt of a MAC withdraw message, all MAC addresses, except the ones learned from the source PE, are flushed. This section specifies that all MAC addresses learned from the source are flushed. This message has been implemented as an LDP address withdraw message with vendor-specific type, length, and value (TLV), and is called the flush-mine message.

The RFC 4762 compliant message is used in VPLS services for recovering from failures in STP (Spanning Tree Protocol) topologies. The mechanism described in this section represents an alternative solution.

The advantage of this approach (as compared to STP-based methods) is that only the affected MAC addresses are flushed and not the full FDB. While this method does not provide a mechanism to secure alternative loop-free topology, the convergence time depends on the speed that the specified CE device opens an alternative link (L2-B switch in Dual-homed CE connection to VPLS) as well as on the speed that PE routers flush their FDB.

In addition, this mechanism is effective only if PE and CE are directly connected (no hub or bridge) as the mechanism reacts to the physical failure of the link.

The use of multichassis ring control in a combination with the plain VPLS SAP is supported by the FDB in individual ring nodes, in case the link (or ring node) failure cannot be cleared on the 7750 SR or 7950 XRS.

This combination is not easily blocked in the CLI. If configured, the combination may be functional but the switchover times are proportional to MAC aging in individual ring nodes or to the relearning rate, or both, because of the downstream traffic.

Redundant plain VPLS access in ring configurations, therefore, exclude corresponding SAPs from the multichassis ring operation. Configurations such as M-VPLS can be applied.

The BGP protocol establishes neighbor relationships between configured peers. An open message is sent after the completion of the three-way TCP handshake. This open message contains information about the BGP peer sending the message. This message contains the Autonomous System Number (ASN), BGP version, timer information, and operational parameters, including capabilities. The capabilities of a peer are exchanged using two numerical values: the Address Family Identifier (AFI) and Subsequent Address Family Identifier (SAFI). These numbers are allocated by the Internet Assigned Numbers Authority (IANA). BGP AD uses AFI 65 (L2VPN) and SAFI 25 (BGP VPLS). For a complete list of allocations, see http://www.iana.org/assignments/address-family-numbers (for AFI) and http://www.iana.org/assignments/safi-namespace (for SAFI).

Following the establishment of the peer relationship, the discovery process begins as soon as a new VPLS service instance is provisioned on the PE.

The following VPLS identifiers are used to indicate the VPLS membership and the individual VPLS instance:

• VPLS-ID

  Membership information, unique network-wide identifier; the same value is assigned for all VPLS Switch Instances (VSIs) belonging to the same VPLS; encodable and carried as a BGP extended community in one of the following formats:

  • A two-octet AS-specific extended community

  • An IPv4 address-specific extended community

• VSI-ID

  The unique identifier for each individual VSI, built by concatenating a route distinguisher (RD) with a 4-byte identifier (usually the system IP of the VPLS PE); encoded and carried in the corresponding BGP Network Layer Reachability Information (NLRI).

To advertise this information, BGP AD uses a simplified version of the BGP VPLS NLRI, where just the RD and the next four bytes are used to identify the VPLS instance. The Label Block and Label Size fields are not needed; T-LDP signals the service labels.

The format of the BGP AD NLRI is very similar to the one used for IP VPN, as shown in the following figure. The system IP may be used for the last four bytes of the VSI-ID, further simplifying the addressing and the provisioning process.

The NLRI is exchanged between BGP peers, indicating how to reach prefixes. The NLRI is used in the Layer 2 VPN case to tell PE peers how to reach the VSI instead of specific prefixes. The advertisement includes the BGP next-hop and a route target (RT). The BGP next-hop indicates the VSI location and is used in the next step to determine which signaling session is used for pseudowire signaling. The RT, also coded as an extended community, can be used to build a VPLS full mesh or an H-VPLS hierarchy through the use of BGP import or export policies.

BGP is only used to discover VPN endpoints and the corresponding far-end PEs; it is not used to signal the pseudowire labels. This task remains the responsibility of T-LDP.

Two LDP FEC elements are defined in RFC 4447, PW Setup & Maintenance Using LDP. The original pseudowire-ID FEC element 128 (0x80) uses a 32-bit field to identify the virtual circuit ID and was used extensively in the initial VPWS and VPLS deployments. The simple format is easy to understand, but it does not provide the required information model for the BGP auto-discovery function. To support BGP AD and other new applications, a new Layer 2 FEC element, the generalized FEC element 129 (0x81) is required.

The generalized pseudowire-ID FEC element has been designed for auto-discovery applications. It provides a field, the Address Group Identifier (AGI), that is used to signal the membership information from the VPLS-ID. Separate address fields are provided for the source and target address associated with the VPLS endpoints, called the Source Attachment Individual Identifier (SAII) and Target Attachment Individual Identifier (TAII), respectively. These fields carry the VSI-ID values for the two instances that are to be connected through the signaled pseudowire.

The detailed format for FEC 129 is shown in the following figure.

Each FEC field is designed as a sub-TLV equipped with its own type and length, providing support for new applications. The following FEC formats are used to accommodate the BGP AD information model.

• AGI (type 1) is identical in format and content to the BGP extended community attribute used to carry the VPLS-ID value.

• Source AII (type 1) is a 4-byte value used to carry the local VSI-ID (outgoing NLRI minus the RD).

• Target AII (type 1) is a 4-byte value used to carry the remote VSI-ID (incoming NLRI minus the RD).

The user can configure the adv-service-mtu command to override the MTU value used in LDP signaling to the far-end of the pseudowire. If the ignore-l2vpn-mtu-mismatch command is not configured, the MTU value is also used to validate the value signaled by the far-end PE.

If the ignore-l2vpn-mtu-mismatch command is configured, the value of the MTU interface parameter received in the FEC element is not checked against the local service MTU, or against the MTU value signaled by the router. The router brings up the VPLS service regardless of any MTU mismatch.

BGP is responsible for discovering the location of VSIs that share the same VPLS membership. LDP protocol is responsible for setting up the pseudowire infrastructure between the related VSIs by exchanging service-specific labels between them.

After the local VPLS information is provisioned in the local PE, the related PEs participating in the same VPLS are identified through BGP AD exchanges. A list of far-end PEs is generated and triggers the creation, if required, of the necessary T-LDP sessions to these PEs and the exchange of the service-specific VPN labels. The steps for the BGP AD discovery process and LDP session establishment and label exchange are shown in BGP AD and T-LDP interaction and described in BGP AD and T-LDP interaction key.

Service Access Points (SAPs) are linked to transport tunnels using service destination points (SDPs). The service architecture allows services to be abstracted from the transport network.

MPLS transport tunnels are signaled using the Resource Reservation Protocol (RSVP-TE) or by the Label Distribution Protocol (LDP). The capability to automatically create an SDP only exists for LDP-based transport tunnels. Using a manually provisioned SDP is available for both RSVP-TE and LDP transport tunnels. For more information about MPLS, LDP and RSVP, see the 7450 ESS, 7750 SR, 7950 XRS, and VSR MPLS Guide.

GRE transport tunnels use GRE encapsulation and can be used with manually provisioned or auto created SDPs.

When BGP AD is used for LDP VPLS, with an LDP or GRE transport tunnel, there is no requirement to manually create an SDP. The LDP or GRE SDP can be automatically instantiated using the information advertised by BGP AD. This simplifies the configuration on the service node.

The use of an automatically created GRE tunnel is enabled by creating the PW template used within the service with the parameter auto-gre-sdp. The GRE SDP and SDP binding is created after a matching BGP route has been received.

Enabling LDP on the IP interfaces connecting all nodes between the ingress and the egress builds transport tunnels based on the best IGP path. LDP bindings are automatically built and stored in the hardware. These entries contain an MPLS label pointing to the best next-hop along the best path toward the destination.

When two endpoints need to connect and no SDP exists, a new SDP is created automatically. New services added between two endpoints that already have an automatically-created SDP are immediately used. No new SDP is created. The far-end information is obtained from the BGP next-hop information in the NLRI. When services are withdrawn with a BGP_Unreach_NLRI, the automatically established SDP remains up as long as at least one service is connected between those endpoints. An automatically created SDP is removed and the resources released when the only or last service is removed.

The service provider has the option of associating the auto-discovered SDP with a split horizon group using the pw-template-binding option, to control the forwarding between pseudowires and to prevent Layer 2 service loops.

An auto-discovered SDP using a pw-template-binding without a split horizon group configured has similar traffic flooding behavior as a spoke-SDP.

The carrier is required to manually provision the SDP if they create transport tunnels using RSVP-TE. Operators have the option to choose a manually configured SDP, if they use LDP as the tunnel signaling protocol. The functionality is the same regardless of the signaling protocol.

Creating a BGP AD enabled VPLS service on an ingress node with the manually provisioned SDP option causes the tunnel manager to search for an existing SDP that connects to the far-end PE. The far-end IP information is obtained from the BGP next-hop information in the NLRI. If a single SDP exists to that PE, it is used. If no SDP is established between the two endpoints, the service remains down until a manually configured SDP becomes active.

When multiple SDPs exist between two endpoints, the tunnel manager selects the appropriate SDP. The algorithm prefers SDPs with the best (lower) metric. If there are multiple SDPs with equal metrics, the operational states of the SDPs with the best metric is considered. If the operational states are the same, the SDP with the higher SDP-ID is used. If an SDP with a preferred metric is found with an operational state that is not active, the tunnel manager flags it as ineligible and restarts the algorithm.

The choice of manual or auto-provisioned SDPs has limited impact on the amount of required provisioning. Most of the savings are achieved through the automatic instantiation of the pseudowire infrastructure (SDP bindings). This is achieved for every auto-discovered VSI through the use of the pseudowire template concept.

Each VPLS service that uses BGP AD contains the pw-template-binding option defining specific Layer 2 VPN parameters. This command references a PW template, which defines the pseudowire parameters. The same PW template may be referenced by multiple VPLS services. As a result, changes to these pseudowire templates have to be treated with caution as they may impact many customers simultaneously.

The Nokia implementation provides for safe handling of pseudowire templates. Changes to the pseudowire templates are not automatically propagated. Tools are provided to evaluate and distribute the changes. The following command is used to distribute changes to a PW template at the service level to one or all services that use that template:

tools perform service id 300 eval-pw-template 1 allow-service-impact

If the service ID is omitted, all services are updated. The type of change made to the PW template influences how the service is impacted.

• Adding or removing a split-horizon-group causes the router to destroy the original object and recreate using the new value.

• Changing parameters in the vc-type {ether | vlan} command requires LDP to re-signal the labels.

Both of these changes are service affecting. Other changes are not service affecting.

The services implementation allows for manually provisioned and auto-discovered pseudowire (SDP bindings) to coexist in the same VPLS instance (for example, both FEC 128 and FEC 129 are supported). This allows for gradual introduction of auto-discovery into an existing VPLS deployment.

As FEC 128 and 129 represent different addressing schemes, it is important to make sure that only one is used at any time between the same two VPLS instances. Otherwise, both pseudowires may become active causing a loop that may adversely impact the correct functioning of the service. It is recommended that FEC 128 pseudowire be disabled as soon as the FEC129 addressing scheme is introduced in a portion of the network. Alternatively, RSTP may be used during the migration as a safety mechanism to provide additional protection against operational errors.

The use of BGP AD on the network side or in the backbone does not affect the resiliency schemes Nokia has developed in the access network. This means that both MC-LAG and M-VPLS can still be used.

BGP AD may coexist with H-VPLS resiliency schemes (for example, dual-homed MTU devices to different PE-rs nodes) using existing methods (M-VPLS and statically configured active or standby pseudowire endpoint).

If provisioned SDPs are used by BGP AD, M-VPLS may be used to provide loop avoidance. However, it is not possible to auto-discover active or standby pseudowires and to instantiate the related endpoint.

The pseudowire is set up using the following NLRI fields:

• VE Block Offset (VBO)

  VBO is used to define for each VE-ID set the NLRI is targeted, as follows:

  • VBO = n*VBS+1; for VBS=8, this results in 1, 9, 17, 25, …

  • Targeted Remote VE-IDs are from VBO to (VBO + VBS - 1)

• VE Block Size (VBS)

  VBS defines how many contiguous pseudowire labels are reserved, starting with the Label Base.

  The Nokia implementation always uses a value of 8.

• Label Base (LB)

  LB is the local allocated label base. The next eight consecutive labels available are allocated for remote PEs.

This BGP update is telling the other PEs that accept the RT: ‟to reach me (VE-ID = x), use a pseudowire label of LB + VE-ID - VBO using the BGP NLRI for which VBO =< local VE-ID < VBO + VBS.

The following is an example of how this algorithm works, assuming PE1 has VE-ID 7 configured.

1. PE1 generates a Label Block of eight consecutive labels, starting with LB = 1000.

2. PE1 then sends BGP update with pseudowire information of (VBO = 1, VBS=8, LB=1000) in the NLRI.

3. This pseudowire information is accepted by all participating PEs with VE-IDs from 1 to 8.

4. Each of the receiving PEs use the pseudowire label = LB + VE-ID - VBO to send traffic back to the originator PE. For example, VE-ID 2 uses pseudowire label 1001.

The following procedure applies assuming that VE-ID = 10 is configured in another PE4.

1. PE4 sends a BGP update with the new VE-ID in the network, which is received by all the other participating PEs, including PE1.

2. PE1, upon reception, generates another label block of 8 labels for the VBO = 9. For example, the initial PE creates new pseudowire signaling information of (VBO = 9, VBS = 8, LB = 3000) and inserts it in a new NLRI and BGP update that is sent in the network.

3. This new NLRI is used by the VE-ID from 9 to 16 to establish pseudowires back to the originator PE1. For example, PE4 with VE-ID 10 uses pseudowire label 3001 to send VPLS traffic back to PE1.

4. The PEs owning the set of VE-IDs from 1 to 8 ignore this NLRI.

In addition to the pseudowire label information, the "Layer2 Info Extended Community" attribute must be included in the BGP update for BGP VPLS to signal the attributes of all the pseudowires that converge toward the originator VPLS PE.

The following figure shows the format for the attribute.

The following list describes the fields shown in the preceding figure:

• Extended Community Type

  The value allocated by IANA for this attribute is 0x800A.

• Encaps Type

  Encapsulation type identifies the type of pseudowire encapsulation. The only value used by BGP VPLS is 19 (13 in HEX).This value identifies the encapsulation to be used for a pseudowire instantiated through BGP signaling, which is the same as the one used for Ethernet pseudowire type for regular VPLS. There is no support for an equivalent Ethernet VLAN pseudowire in BGP VPLS in BGP signaling.

• Control Flags

  The control information about the pseudowires (see BGP VPLS solution).

  Control flags bit vector shows the Control Flags bit vector.

• Layer-2 MTU

  The Maximum Transmission Unit to be used on the pseudowires.

• Reserved

  This field is reserved and must be set to zero and ignored on reception except where it is used for VPLS preference.

  For inter-AS, the preference information must be propagated between autonomous systems. Consequently, as the VPLS preference in a BGP-VPLS or BGP multihoming update extended community is zero, the local preference is copied by the egress ASBR into the VPLS preference field before sending the update to the EBGP peer. The adjacent ingress ASBR then copies the received VPLS preference into the local preference to prevent the update being considered malformed.

The following figure shows the detailed format for the Control Flags bit vector.

The bits in the Control Flags are defined as follows:

• S

  Sequenced delivery of frames must or must not be used when sending VPLS packets to this PE, depending on whether S is 1 or 0, respectively.

• C

  A control word must or must not be present when sending VPLS packets to this PE, depending on whether C is 1 or 0, respectively. By default, Nokia implementation uses value 0.

• MBZ

  Must Be Zero bits, set to zero when sending and ignored when receiving.

• D

  The status of the whole VPLS instance (VSI); D=0 if Admin and Operational status are up, D=1 otherwise.

The events that set the D-bit to 1 to indicate VSI down status in a BGP update message sent out from a PE are as follows.

• Local VSI is shutdown administratively using the configure service vpls shutdown command.

• All the related endpoints (SAPs or LDP pseudowires) are down.

• There are no related endpoints (SAPs or LDP pseudowires) configured yet in the VSI. The intent is to save the core bandwidth by not establishing the BGP pseudowires to an empty VSI.

• Upon reception of a BGP update message with D-bit set to 1, all the receiving VPLS PEs must mark related pseudowires as down.

The following events do not set the D-bit to 1:

• the local VSI is deleted

  A BGP update with unreach-NLRI is sent out. Upon reception, all remote VPLS PEs must remove the related pseudowires and BGP routes.

• the local SDP goes down

  Only the BGP pseudowires mapped to that SDP goes down. There is no BGP update sent.

The adv-service-mtu command can be used to override the MTU value used in BGP signaling to the far-end of the pseudowire. This value is also used to validate the value signaled by the far-end PE unless ignore-l2vpn-mtu-mismatch is also configured.

If the ignore-l2vpn-mtu-mismatch command is configured, the router does not check the value of the "Layer 2 MTU" in the "Layer2 Info Extended Community" received in a BGP update message against the local service MTU, or against the MTU value signaled by this router. The router brings up the BGP VPLS service regardless of any MTU mismatch.

BGP VPLS supports a new type of pseudowire signaling based on MP-BGP. It makes use of VPLS and inherits all the existing Ethernet switching functions.

The use of an automatically created GRE tunnel is enabled by creating the PW template used within the service with the parameter auto-gre-sdp. The GRE SDP and SDP binding is created after a matching BGP route has been received.

The following are some of the most important VPLS features that are also ported to BGP VPLS:

• VPLS data plane features (for example, FDB management, SAPs, LAG access, and BUM rate limiting)

• MPLS tunneling: LDP, LDP over RSVP-TE, RSVP-TE, GRE, and MP-BGP based on RFC 8277 (Inter-AS option C solution)

  Note: Pre-provisioned SDPs must be configured when RSVP-signaled transport tunnels are used.

• H-VPLS topologies, hub and spoke traffic distribution

• coexistence with LDP VPLS (with or without BGP AD) in the same VPLS instance

  Note: LDP and BGP signaling should operate in disjoint domains to simplify loop avoidance.

• Coexists with BGP-based multihoming

• BGP VPLS is supported as the control plane for B-VPLS

• Supports IGMP/PIM snooping for IPv4

• High Availability (HA)

• Ethernet service OAM toolset (IEEE 802.1ag and Y.1731)

  Note: CPE ping, MAC trace, MAC ping, MAC populate, and MAC purge are not supported.

• Support for RSVP and LSP P2MP LSP for VPLS/B-VPLS BUM

VPLS Multihoming using BGP-MP expands on the BGP AD and BGP VPLS provisioning model. The addressing for the multihomed site is still independent from the addressing for the base VSI (VSI-ID or, respectively, VE-ID). Every multihomed CE is represented in the VPLS context through a site-ID, which is the same on the local PEs. The site-ID is unique within the scope of a VPLS. It serves to differentiate between the multihomed CEs connected to the same VPLS Instance (VSI). For example, in BGP MH-NLRI for VPLS multihoming, CE5 is assigned the same site-ID on both PE1 and PE4. For the same VPLS instance, different site-IDs are assigned for multihomed CE5 and CE6; for example, site-ID 5 is assigned for CE5 and site-ID 6 is assigned for CE6. The single-homed CEs (CE1, 2, 3, and 4) do not require allocation of a multihomed site-ID. They are associated with the addressing for the base VSI, either VSI-ID or VE-ID.

The new information model required changes to the BGP usage of the NLRI for VPLS. The extended MH NLRI for Multi-Homed VPLS is compared with the BGP AD and BGP VPLS NLRIs in BGP MH-NLRI for VPLS multihoming.

The BGP VPLS NLRI described in RFC 4761 is used to carry a 2-byte site-ID that identifies the MH site. The last seven bytes of the BGP VPLS NLRI used to instantiate the pseudowire are not used for BGP-MH and are zeroed out. This NLRI format translates into the following processing path in the receiving VPLS PE:

• BGP VPLS PE: no label information means there is no need to set up a BGP pseudowire.

• BGP AD for LDP VPLS: length =17 indicates a BGP VPLS NLRI that does not require any pseudowire LDP signaling.

The processing procedures described in this section start from the above identification of the BGP update as not destined for pseudowire signaling.

The RD ensures that the NLRIs associated with a specific site-ID on different PEs are seen as different by any of the intermediate BGP nodes (RRs) on the path between the multihomed PEs. That is, different RDs must be used on the MH PEs every time an RR or an ASBR is involved to guarantee the MH NLRIs reach the PEs involved in VPLS MH.

The L2-Info extended community from RFC 4761 is used in the BGP update for MH NLRI to initiate a MAC flush for blackhole avoidance, to indicate the operational and admin status for the MH site or the DF election status.

After the pseudowire infrastructure between VSIs is built using either RFC 4762, Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling, or RFC 4761 procedures, or a mix of pseudowire signaling procedures, on activation of a multihomed site, an election algorithm must be run on the local and remote PEs to determine which site is the designated forwarder (DF). The end result is that all the related MH sites in a VPLS are placed in standby except for the site selected as DF. Nokia BGP-based multihoming solution uses the DF election procedure described in the IETF working group document draft-ietf-bess-vpls-multihoming-01. The implementation allows the use of BGP local preference and the received VPLS preference but does not support setting the VPLS preference to a non-zero value.

This feature is supported for the following services:

• LDP VPLS with or without BGP-AD

• BGP VPLS (BGP multihoming for inter-AS BGP-VPLS services is not supported)

• mix of the above

• PBB B-VPLS on BCB

• PBB I-VPLS (see IEEE 802.1ah Provider Backbone Bridging for more information)

The following access objects can be associated with MH Site:

• SAPs

• SDP bindings (pseudowire object), both mesh-SDP and spoke-SDP

• Split Horizon Group

  Under the SHG we can associate either one or multiple of the following objects: SAPs, pseudowires (BGP VPLS, BGP-AD, provisioned and LDP-signaled spoke-SDP and mesh-SDP)

Blackholing refers to the forwarding of frames to a PE that is no longer carrying the designated forwarder. This could happen for traffic from:

• Core PE participating in the main VPLS

• Customer Edge devices (CEs)

• Access PEs (pseudowires between them and the MH PEs are associated with MH sites)

Changes in DF election results or MH site status must be detected by all of the above network elements to provide for Blackhole Avoidance.

BGP MH for VPLS can be used to provide resiliency between different VPLS domains. An example of a multihoming topology is shown in BGP MH used in an HVPLS topology.

LDP VPLS domains are interconnected using a core VPLS domain, either BGP VPLS or LDP VPLS. The gateway PEs, for example PE2 and PE3, are running BGP multihoming where one MH site is assigned to each of the pseudowires connecting the access PE, PE7, and PE8 in this example.

Alternatively, the MH site can be associated with multiple access pseudowires using an access SHG. The configure service vpls site failed-threshold command can be used to indicate the number of pseudowire failures that are required for the MH site to be declared down.

When IGMP snooping is enabled in a VPLS service, IGMP messages received on SAPs and SDPs are snooped to determine the scope of flooding for a specified stream or (S,G). IGMP snooping operates in a proxy mode, where the system summarizes upstream IGMP reports and responds to downstream queries.

For a description of IGMP snooping, see the 7450 ESS, 7750 SR, and VSR Triple Play Service Delivery Architecture Guide, "IGMP Snooping".

Streams are sent to all SAPs and SDPs on which there is a multicast router (either discovered dynamically from received query messages or configured statically using the mrouter-port command) and on which an active join for that stream has been received. The mrouter port configuration adds a (*,*) entry into the MFIB, which causes all groups (and IGMP messages) to be sent out of the respective object and causes IGMP messages received on that object to be discarded.

Directly-connected multicast sources are supported when IGMP snooping is enabled.

IGMP snooping is enabled at the service level.

IGMP is not supported on the following:

• B-VPLS, routed I-VPLS, PBB-VPLS services

• a router configured with enable-inter-as-vpn or enable-rr-vpn-forwarding

• the following forms of default SAP:

  • *

  • *.null

  • *.*

• a VPLS service configured with a connection profile VLAN SAP

MLD snooping is an IPv6 version of IGMP snooping, and the guidelines and procedures are similar; see IGMP snooping for VPLS for more information. However, MLD snooping uses MAC-based forwarding. See MAC-based IPv6 multicast forwarding for more information. Directly connected multicast sources are supported when MLD snooping is enabled.

MLD snooping is enabled at the service level with the following restrictions.

• MLD snooping is not supported in the following services:

  • B-VPLS

  • Routed I-VPLS

  • EVPN-MPLS services

  • PBB-EVPN services

• MLD snooping is not supported under the following forms of default SAP:

  • *

  • *.null

  • *.*

• MLD snooping is not supported in a VPLS service configured with a connection profile VLAN SAP.

PIM snooping for VPLS allows a VPLS PE router to build multicast states by snooping PIM protocol packets that are sent over the VPLS. The VPLS PE then forwards multicast traffic based on the multicast states. When all receivers in a VPLS are IP multicast routers running PIM, multicast forwarding in the VPLS is efficient when PIM snooping for VPLS is enabled.

Because of PIM join/prune suppression, to make PIM snooping operate over VPLS pseudowires, two options are available: plain PIM snooping and PIM proxy. PIM proxy is the default behavior when PIM snooping is enabled for a VPLS.

PIM snooping is supported for both IPv4 and IPv6 multicast by default and can be configured to use SG-based forwarding (see IPv6 multicast forwarding for more information).

Directly connected multicast sources are supported when PIM snooping is enabled.

The following restrictions apply to PIM snooping:

• PIM snooping for IPv4 and IPv6 is not supported:

  • in the following services:

    • PBB B-VPLS

    • R-VPLS (including I-VPLS and BGP EVPN)

    • PBB-EVPN B-VPLS

    • EVPN-VXLAN R-VPLS

  • on a router configured with enable-inter-as-vpn or enable-rr-vpn-forwarding

  • under the following forms of default SAP:

    • *

    • *.null

    • *.*

  • in a VPLS service configured with a connection profile VLAN SAP

  • with connected SR OSs configured with improved-assert

  • with subscriber management in the VPLS service

  • as a mechanism to drive MCAC

• PIM snooping for IPv6 is not supported:

  • in the following services:

    • PBB I-VPLS

    • BGP-VPLS

    • BGP EVPN (including PBB-EVPN)

    • VPLS E-Tree

    • Management VPLS

  • with the configuration of MLD snooping

When MLD snooping or PIM snooping for IPv6 is enabled, the forwarding of IPv6 multicast traffic is MAC-based; see MAC-based IPv6 multicast forwarding for more information.

The operation with PIM snooping for IPv6 can be changed to SG-based forwarding; see SG-based IPv6 multicast forwarding for more information.

The following command configures the IPv6 multicast forwarding mode with the default being mac-based:

configure service vpls mcast-ipv6-snooping-scope {sg-based | mac-based}

The forwarding mode can only be changed when PIM snooping for IPv6 is disabled.

When both PIM snooping for IPv4 and IGMP snooping are enabled in the same VPLS service, multicast traffic is forwarded based on the combined multicast forwarding table. When PIM snooping is enabled, IGMP queries are forwarded but not snooped, consequently the IGMP querier needs to be seen either as a PIM neighbor in the VPLS service or the SAP toward it configured as an IGMP Mrouter port.

There is no interaction between PIM snooping for IPv6 and PIM snooping for IPv4/IGMP snooping when all are enabled within the same VPLS service. The configurations of PIM snooping for IPv6 and MLD snooping are mutually exclusive.

When PIM snooping is enabled within a VPLS service, all IP multicast traffic and flooded PIM messages (these include all PIM snooped messages when not in PIM proxy mode and PIM hellos when in PIM proxy mode) are sent to any SAP or SDP binding configured with an IGMP-snooping Mrouter port. This occurs even without IGMP-snooping enabled but is not supported in a BGP-VPLS or M-VPLS service.

To achieve a faster failover in scenarios with redundant active/standby routers performing Layer 2 multicast snooping, it is possible to synchronize the snooping state from the active router to the standby router, so that if a failure occurs the standby router has the Layer 2 multicast snooped states and is able to forward the multicast traffic immediately. Without this capability, there would be a longer delay in re-establishing the multicast traffic path because it would wait for the Layer 2 states to be snooped.

Multichassis synchronization (MCS) is enabled per peer router and uses a sync-tag, which is configured on the objects requiring synchronization on both of the routers. This allows MCS to map the state of a set of objects on one router to a set of objects on the other router. Specifically, objects relating to a sync-tag on one router are backed up by, or are backing up, the objects using the same sync-tag on the other router (the state is synchronized from the active object on one router to its backup objects on the standby router).

The object type must be the same on both routers; otherwise, a mismatch error is reported. The same sync-tag value can be reused for multiple peer/object combinations, where each combination represents a different set of synchronized objects; however, a sync-tag cannot be configured on the same object to more than one peer.

The sync-tag is configured per port and can relate to a specific set of dot1q or QinQ VLANs on that port, as follows.

CLI syntax:

configure
  redundancy
    multi-chassis
      peer ip-address [create]
        sync
          port port-id [sync-tag sync-tag] [create]
            range encap-range sync-tag sync-tag

For IGMP snooping and PIM snooping for IPv4 to work correctly with MCS on QinQ ports using x.* SAPs, one of the following must be true:

• MCS is configured with a sync-tag for the entire port.

• The IGMP snooping SAP and the MCS sync-tag must be provisioned with the same Q-tag values when using the range parameter.

The following features are High Availability capable:

• Configuration redundancy (all the VPLS multicast-aware configurations can be synchronized to the standby CPM)

• Local snooping states as well as states distributed by LDP can be synchronized to the standby CPM.

• Operational states can also be synchronized; for example, the operational state of PIM proxy.

When a service name is applied to any service context, the name and service ID association is registered with the system. Assigning a service name to more than one service ID is not allowed.

There is special consideration for a service name that is assigned to a VPLS service on which the config service vpls allow-ip-int-bind command is enabled. In such cases the system scans the existing IES and VPRN services for an IP interface that is bound to the specified service name. If an IP interface is found, the IP interface is attached to the VPLS service associated with the name. Only one interface can be bound to the specified name.

If the allow-ip-int-bind command is not enabled on the VPLS service, the system does not attempt to resolve the VPLS service name to an IP interface. As soon as the allow-ip-int-bind flag is configured on the VPLS, the corresponding IP interface is bound and becomes operationally up. Toggling the shutdown and no shutdown command is not required.

If an IP interface is not currently bound to the service name used by the VPLS service, no action is taken at the time of the service name assignment.

If the defined service ID is created on the system, the system checks to ensure that the service type is VPLS. If the service type is not VPLS or I-VPLS, service creation is not allowed and the service ID remains undefined within the system.

If the created service type is VPLS, the IP interface is eligible to enter the operationally up state.

If a bound service name is assigned to a service within the system, the system first checks to ensure the service type is VPLS or I-VPLS. Secondly, the system ensures that the service is not already bound to another IP interface through the service ID. If the service type is not VPLS or I-VPLS or the service is already bound to another IP interface through the service ID, the service name assignment fails.

If a single VPLS service ID and service name is assigned to two separate IP interfaces, the VPLS service is not allowed to enter the operationally up state.

An IP interface within an IES or VPRN service context may be bound to a service name at any time. Only one interface can be bound to a service.

When an IP interface is bound to a service name and the IP interface is administratively up, the system scans for a VPLS service context using the name and performs the following actions.

• If the name is not currently in use by a service, the IP interface is placed in an operationally down state: non-existent service name or inappropriate service type.

• If the name is currently in use by a non-VPLS service or the wrong type of VPLS service, the IP interface is placed in the operationally down state: non-existent service name or inappropriate service type.

• If the name is currently in use by a VPLS service without the allow-ip-int-bind command enabled, the IP interface is placed in the operationally down state: VPLS service allow-ip-int-bind flag not set. Toggling the shutdown/no shutdown command is not required.

• If the name is currently in use by a valid VPLS service and the allow-ip-int-bind command is enabled, the IP interface is eligible to be placed in the operationally up state, if other operational criteria is met.

If a VPLS service is deleted while bound to an IP interface, the IP interface enters the ‟Down: Non-existent svc-ID” operational state. If the IP interface was bound to the VPLS service name, the IP interface enters the ‟Down: Non-existent svc-name” operational state. A console warning is not generated.

If the created service type is VPLS, the IP interface is eligible to enter the operationally up state.

After a VPLS service has been bound to an IP interface through its service name, the assigned service name cannot be removed or changed, unless the IP interface is first unbound from the VPLS service name.

A VPLS service that is currently attached to an IP interface cannot be deleted from the system, unless the IP interface is unbound from the VPLS service name.

The allow-ip-int-bind flag in an IP interface-attached VPLS service cannot be reset, unless the IP interface is first unbound from the VPLS service name.

When the IP interface is successfully attached to a VPLS service, the operational state of the IP interface is dependent upon the operational state of the VPLS service.

The VPLS service remains down until at least one virtual port (SAP, spoke-SDP, or mesh SDP) is operational.

The VPLS service MTU and the IP interface MTU parameters may be changed at any time.

In typical routing behavior, the system uses the IP route table to select the egress interface, and then at the egress forwarding engine, an ARP entry is used to forward the packet to the appropriate Ethernet MAC. With R-VPLS, the egress IP interface may be represented by a multiple egress forwarding engine (wherever the VPLS service virtual ports exist).

To optimize routing performance, the ingress forwarding engine processing is augmented to perform an ingress ARP lookup to resolve which VPLS MAC address the IP frame must be routed toward. This MAC address may be currently known or unknown within the VPLS FDB. If the MAC is unknown, the ingress forwarding engine floods the packet to all egress forwarding engines where the VPLS service exists. If the MAC is known on a virtual port, the ingress forwarding engine forwards the packet to the correct egress forwarding engine. The following table describes how the ARP cache and MAC FDB entry states interact at ingress.

The following table describes the corresponding egress behavior.

The allow-ip-int-bind flag is set (routing support enabled) on a VPLS/I-VPLS service. SAPs within the service can be created on standard Ethernet, and CCAG ports. POS is not supported.

If a LAG has a non-supported port type as a member, a SAP for the routing-enabled VPLS service cannot be created on the LAG. When one or more routing enabled VPLS SAPs are associated with a LAG, a non-supported Ethernet port type cannot be added to the LAG membership.

When the allow-ip-int-bind flag is set on a VPLS service, the following restrictions apply. The flag also cannot be enabled while any of these features are applied to the VPLS service:

• SDPs used in spoke or mesh SDP bindings cannot be configured as GRE.

• The VPLS service type cannot be B-VPLS or M-VPLS.

• MVR from R-VPLS and to another SAP is not supported.

• Enhanced and Basic Subscriber Management (BSM) features cannot be enabled.

• Network domain on SDP bindings cannot be enabled.

• Per-service hashing is not supported.

• BGP-VPLS is not supported.

• Ingress queuing for split horizon groups is not supported.

• Multiple virtual routers are not supported.

The following restrictions apply to routed I-VPLS.

• Multicast is not supported.

• The VC-VLANs are not supported on SDPs.

• The force-qtag-forwarding command is not supported.

• Control words are not supported on B-VPLS SDPs.

• The hash label is not supported on B-VPLS SDPs.

• The provider-tunnel is not supported on routed I-VPLS services.

When an IP Interface is attached to a VPLS or an I-VPLS service context, the VPLS SAP provisioned IP or IPv6 filter for ingress routed packets may be optionally overridden to provide special ingress filtering for routed packets. The filter override is defined on the IP interface bound to the VPLS service name. A separate override filter may be specified for IPv4 and IPv6 packet types. The filter override applies to unicast routed packets destined to the routed VPLS interface MAC address.

If a filter for a specified packet type (IPv4 or IPv6) is not overridden, the SAP specified filter is applied to the packet (if defined).

The SAP egress QoS policy defined forwarding class and profile reclassification rules are not applied to egress routed packets. To allow for egress reclassification, a SAP egress QoS policy ID may be optionally defined on the IP interface that is applied to routed packets that egress the SAPs on the VPLS or I-VPLS service associated with the IP interface. Both unicast directed and MAC unknown flooded traffic apply to this rule. Only the reclassification portion of the QoS policy is applied, which includes IP precedence or DSCP classification rules and any defined IP match criteria and their associated actions.

The policers and queues defined within the QoS policy applied to the IP interface are not created on the egress SAPs of the VPLS service. Instead, the QoS policy applied to the egress SAPs defines the egress policers and queues used by both routed and non-routed egress packets. The forwarding class mappings defined in the egress SAP’s QoS policy also defines which policer or queue handles each forwarding class for both routed and non-routed packets.

The remarking of packets to and from an IP interface in an R-VPLS service corresponds to that supported on IP interface, even though the packets ingress or egress a SAP in the VPLS service bound to the IP service. Specifically, this results in the ability to remark the DSCP/prec for these packets.

Packets that ingress and egress SAPs in the VPLS service (not routed through the IP interface) support the regular VPLS QoS and, therefore, the DSCP/prec cannot be remarked.

When using IPv4 multicast routing, the following are not supported:

• The multicast VLAN registration functions within the associated VPLS service.

• The configuration of a video ISA within the associated VPLS service.

• The configuration of MFIB-allowed MDA destinations under spoke/mesh SDPs within the associated VPLS service.

• The IPv4 multicast routing is not supported in Routed I-VPLS.

• The RFC 6037 multicast tunnel termination (including when the system is a bud node) is not supported on the R-VPLS IP interface for multicast traffic received in the VPLS service.

• Forwarding of multicast traffic from the VPLS side of the service to the IP interface side of the service is not supported for R-VPLS services that have egress VXLAN VTEPs configured.

The following protocols are supported on IP interfaces bound to a VPLS service:

• BGP

• OSPF

• ISIS

• PIM

• IGMP

• BFD

• VRRP

• ARP

• DHCP Relay

A R-VPLS context supports all spanning tree and split horizon capabilities that a non-R-VPLS service supports.

The following provisioning steps apply.

1. Configure the M-VPLS instances in the switches that participate in MVRP control plane.

2. Configure under the M-VPLS the untagged SAPs to be used for MVRP exchanges; only dot1q or QinQ ports are accepted for MVRP enabled M-VPLS.

3. Configure the MVRP parameters at M-VPLS instance or SAP level.

This requires the configuration in the M-VPLS, under vpls-group, of the following attributes: VLAN ranges, vpls-template and vpls-sap-template bindings. As soon as the VPLS group is enabled, the configured attributes are used to auto-instantiate, on a per-VLAN basis, a VPLS FDB and related SAPs in the switches and on the ‟trunk ports” specified in the M-VPLS context. The trunk ports are ports associated with an M-VPLS SAP not configured as an end-station.

The following procedure is used:

• The vpls-template binding is used to instantiate the VPLS instance where the service ID is derived from the VLAN value as per service-range configuration.

• The vpls-sap-template binding is used to create dot1q SAPs by deriving from the VLAN value the service delimiter as per service-range configuration.

The above procedure may be used outside of the MVRP context to pre-provision a large number of VPLS contexts that share the same infrastructure and attributes.

The MVRP control of the auto-instantiated services can be enabled using the mvrp-control command under the vpls-group.

• If mvrp-control is disabled, the auto-created VPLS instances and related SAPs are ready to forward.

• If mvrp-control is enabled, the auto-created VPLS instances are instantiated initially with an empty flooding domain. According to the operator configuration the MVRP exchanges gradually enable service connectivity – between configured SAPs in the data VPLS context.

  This also provides protection against operational mistakes that may generate flooding throughout the auto-instantiated VLAN FDBs.

From an MVRP perspective, these SAPs can be either ‟full MVRP” or ‟end-station” interfaces.

A full MVRP interface is a full participant in the local M-VPLS scope as described below.

• VLAN attributes received in an MVRP registration on this MVRP interface are declared on all the other full MVRP SAPs in the control VPLS.

• VLAN attributes received in an MVRP registration on other full MVRP interfaces in the local M-VPLS context are declared on this MVRP interface.

In an MVRP end-station interface, the attributes registered on that interface have local significance, as described below.

• VLAN attributes received in an MVRP registration on this interface are not declared on any other MVRP SAPs in the control VPLS. The attributes are registered only on the local port.

• Only locally active VLAN attributes are declared on the end-station interface; VLAN attributes registered on any other MVRP interfaces are not declared on end-station interfaces.

• Also defining an M-VPLS SAP as an end-station does not instantiate any objects on the local switch; the command is used just to define which SAP needs to be monitored by MVRP to declare the related VLAN value.

The following example describes the M-VPLS configuration required to auto-instantiate the VLAN FDBs and related trunks in non-PBB switches.

mrp
        — no shutdown
        — mmrp
            — shutdown
        — mvrp
            — no shutdown
    sap 1/1/1:0
        — mrp mvrp
            — no shutdown
    sap 2/1/2:0
        — mrp mvrp
            — no shutdown
    sap 3/1/10:0
        — mrp mvrp
            — no shutdown
    vpls-group 1
        — service-range 100-2000
        — vpls-template-binding Autovpls1
        — sap-template-binding Autosap1
            — mvrp-control
        — no shutdown

A similar M-VPLS configuration may be used to auto-instantiate the VLAN FDBs and related trunks in PBB switches. The vpls-group command is replaced by the end-station command under the downward-facing SAPs as in the following example.

config>service>vpls control-mvrp m-vpls create customer 1
        — [..]
        — sap 1/1/1:0
            — mvrp mvrp
                — endstation-vid-group 1 vlan-id 100-2000
                — no shutdown

As new Ethernet services are activated, UNI SAPs need to be configured and associated with the VLAN IDs (VPLS instances) auto-created using the procedures described in the previous sections. These UNI SAPs may be located in the same VLAN domain or over a PBB backbone. When UNI SAPs are located in different VLAN domains, an intermediate service translation point must be used at the PBB BEB, which maps the local VLAN ID through an I-VPLS SAP to a PBB ISID. This BEB SAP is playing the role of an end-station from an MVRP perspective for the local VLAN domain.

This section discusses how MVRP is used to activate service connectivity between a BEB SAP and a UNI SAP located on one of the switches in the local domain. A similar procedure is used in the case of UNI SAPs configured on two switches located in the same access domain. No end-station configuration is required on the PBB BEB if all the UNI SAPs in a service are located in the same VLAN domain.

The service connectivity instantiation through MVRP is shown in Service instantiation with MVRP - QinQ to PBB example.

In this example, the UNI and service translation SAPs are configured in the data VPLS represented by the gray circles. This instance and associated trunk SAPs were instantiated using the procedures described in the previous sections. The following are configuration rules:

• on the BEB, an I-VPLS SAP must be configured toward the local switching domain (see yellow triangle facing downward in Service instantiation with MVRP - QinQ to PBB example).

• on the UNI facing the customer, a ‟customer” SAP is configured on the lower left switch (see yellow triangle facing upward in Service instantiation with MVRP - QinQ to PBB example).

As soon as the first UNI SAP becomes active in the data VPLS on the ES, the associated VLAN value is advertised by MVRP throughout the related M-VPLS context. As soon as the second UNI SAP becomes available on a different switch, or in our example on the PBB BEB, the MVRP proceeds to advertise the associated VLAN value throughout the same M-VPLS. The trunks that experience MVRP declaration and registration in both directions become active, instantiating service connectivity as represented by the big and small yellow circles shown in the figure.

A hold-time parameter (config>service>vpls>mrp>mvrp>hold-time) is provided in the M-VPLS configuration to control when the end-station or last UNI SAP is considered active from an MVRP perspective. The hold-time controls the amount of MVRP advertisements generated on fast transitions of the end-station or UNI SAPs.

If the no hold-time setting is used, the following rules apply:

• MVRP stops declaring the VLAN only when the last provisioned UNI SAP associated locally with the service is deleted.

• MVRP starts declaring the VLAN as soon as the first provisioned SAP is created in the associated VPLS instance, regardless of the operational state of the SAP.

If a non-zero ‟hold-time” setting is used, the following rules apply:

• When a SAP in down state is added, MVRP does not declare the associated VLAN attribute. The attribute is declared immediately when the SAP comes up.

• When the SAP goes down, the MVRP waits until ‟hold-time” expiry before withdrawing the declaration.

For QinQ end-station SAPs, only no hold-time setting is allowed.

Only the following PBB Epipe and I-VPLS SAP types are eligible to activate MVRP declarations:

• dot1q: for example, 1/1/2:100

• qinq or qinq default: for example, 1/1/1:100.1 and respectively 1/1/1:100.*, respectively; the outer VLAN 100 is used as MVRP attribute as long as it belongs to the MVRP range configured for the port

• null port and dot1q default cannot be used

Examples of steps required to activate service connectivity for VLAN 100 using MVRP follows.

In the data VPLS instance (VLAN 100) controlled by MVRP, on the QinQ switch, example:

config>service>vpls 100
        — sap 9/1/1:10 //UNI sap using CVID 10 as service delimiter
            — no shutdown

In I-VPLS on PBB BEB, example:

config>service>vpls 1000 i-vpls
        — sap 8/1/2:100 //sap (using MVRP VLAN 100 on endstation port in M-VPLS
            — no shutdown

MVRP is based on the IEEE 802.1ak MRP specification where STP is the supported method to be used for loop avoidance in a native Ethernet environment. M-VPLS and the associated MSTP (or P-MSTP) control plane provides the loop avoidance component in the Nokia implementation. Nokia MVRP may also be used in a non-MSTP, loop-free topology.

MSTP and MVRP interaction table shows the expected interaction between STP (MSTP or P-MSTP) and MVRP.

The VPLS E-Tree service offers a VPLS service with Root and Leaf designated access SAPs and SDP bindings, which prevent any traffic flow from leaf to leaf directly. With a VPLS E-Tree, the split horizon group capability is inherent for leaf SAPs (or SDP bindings) and extends to all the remote PEs that are part of the same VPLS E-Tree service. This feature is based on IETF Draft draft-ietf-l2vpn-vpls-pe-etree.

A VPLS E-Tree service may support an arbitrary number of leaf access (leaf-ac) interfaces, root access (root-ac) interfaces, and root-leaf tagged (root-leaf-tag) interfaces. Leaf-ac interfaces are supported on SAPs and SDP binds and can only communicate with root-ac interfaces (also supported on SAPs and SDP binds). Leaf-ac to leaf-ac communication is not allowed. Root-leaf-tag interfaces (supported on SAPs and SDP bindings) are tagged with root and leaf VIDs to allow remote VPLS instances to enforce the E-Tree forwarding.

E-Tree service shows a network with two root-ac interfaces and several leaf-ac SAPs (also could be SDPs). The figure indicates two VIDs in use to each service within the service with no restrictions on the AC interfaces. The service guarantees no leaf-ac to leaf-ac traffic.

Mapping PE model to VPLS service shows the terminology used for E-Tree in IETF Draft draft-ietf-l2vpn-vpls-pe-etree and a mapping to SR OS terms.

An Ethernet service access SAP is characterized as either a leaf-ac or a root-ac for a VPLS E-Tree service. As far as SR OS is concerned, these are normal SAPs with either no tag (Null), priority tag, or dot1q or QinQ encapsulation on the frame. Functionally, a root-ac is a normal SAP and does not need to be differentiated from the regular SAPs except that it is associated with a root behavior in a VPLS E-Tree.

Leaf-ac SAPs have restrictions; for example, a SAP configured for a leaf-ac can never send frames to another leaf-ac directly (local) or through a remote node. Leaf-ac SAPs on the same VPLS instance behave as if they are part of a split horizon group (SHG) locally. Leaf-ac SAPs that are on other nodes need to have the traffic marked as originating ‟from a Leaf” in the context of the VPLS service when carried on PWs and SAPs with tags (VLANs).

Root-ac SAPs on the same VPLS can talk to any root-ac or leaf-ac.

Untagged SDP binds for access can also be designated as root-ac or leaf-ac. This type of E-Tree interface is required for devices that do not support E-Tree, such as the 7210 SAS, to enable them to be connected with pseudowires. Such devices are root or leaf only and do not require having a tagged frame with a root or leaf indication.

Support on root-leaf-tag SAPs requires that the outer VID is overloaded to indicate root and leaf. To support the SR service model for a SAP, the ability to send and receive two different tags on a single SAP has been added. Leaf and root tagging dot1q shows the behavior when a root-ac and leaf-ac exchange traffic over a root-leaf-tag SAP. Although the figure shows two SAPs connecting VPLS instances 1 and 2, the CLI shows a single SAP with the format:

sap 2/1/1:25 root-leaf-tag leaf-tag 26 create

The root-leaf-tag SAP performs all of the operations for egress and ingress traffic for both tags (root and leaf):

• When receiving a frame, the outer tag VID is compared against the configured root or leaf VIDs and the frame forwarded accordingly.

• When transmitting, the system adds a root VLAN (in the outer tag) on frames with an internal indication of Root, and a leaf VLAN on frames with an internal indication of Leaf.

Typically, in a VPLS environment over MPLS, mesh and spoke-SDP binds interconnect the local VPLS instances to remote PEs. To support VPLS E-Tree, the root and leaf traffic is sent over the SDP bind using a fixed VLAN tag value. The SR OS implementation uses a fixed VLAN ID 1 for root and fixed VLAN ID 2 for leaf. The root and leaf tags are considered a global value and signaling is not supported. The vc-type on root-leaf-tag SDP binds must be VLAN. The vlan-vc-tag command is blocked in root-leaf-tag SDP-binds.

Leaf and root tagging PW shows the behavior when leaf-ac or root-ac interfaces exchange traffic over a root-leaf-tag SDP-binding.

As a general rule, any CPM-generated traffic is always root traffic (STP, OAM, and so on) and any received control plane frame is marked with a root/leaf indication based on which E-Tree interface it arrived at. Some other particular feature interactions are as follows:

• ETH-CFM and E-Tree have limited conjunctive uses. ETH-CFM allows the operator to verify connectivity between the various endpoints of the service as well as execute troubleshooting and performance gathering functions. Continuity Checking, ETH-CC, is a method by which endpoints are configured and messages are passed between them at regular configured intervals. When CCM-enabled MEPs are configured, all MEPs in the same maintenance association, the grouping typically along the service lines, must know about every other endpoint in the service. This is the main principle behind continuity verification (all endpoints in communication).

  Although the maintenance points configured within the E-Tree service adhere to the forwarding rules of the Leaf and the Root, local population of the MEP database used by the ETH-CFM function may make it appear that the forwarding plane is broken when it is not. All MEPs that are locally configured within a service are automatically added to the local MEP database. However, because of the Leaf and Root forwarding rules, not all of these MEPs can receive the required peer CCM-message to avoid CCM Defect conditions. It is suggested, when deploying CCM enabled MEPs in an E-Tree configuration, these CCM-enabled MEPs are configured on Root entities. If Leaf access requires CCM verification, then down MEPs in separate maintenance associations should be configured. This consideration is only for operators who need to deploy CCM in E-Tree environments. No other ETH-CFM tools query or use this database.

• Legacy OAM commands (cpe-ping, mac-ping, mac-trace, mac-populate, and mac-purge) are not supported in E-Tree service contexts. Although some configuration may result in normal behavior for some commands, not all commands or configurations yield the expected results. Standards-based ETH-CFM tools should be used in place of the proprietary legacy OAM command set.

• IGMP and PIM snooping for IPv4 work on VPLS E-Tree services. Routers should use root-ac interfaces so the multicast traffic can be delivered properly.

• xSTP is supported in VPLS E-Tree services; however, when configuring STP in VPLS E-Tree services, the following considerations apply:

  • STP must be carefully used so that STP does not block needless objects.

  • xSTP is not aware of the leaf-to-leaf topology; for example, for leaf-to-leaf traffic, even if there is no loop in the forwarding plane, xSTP may block leaf-ac SAPs or SDP binds.

  • Because xSTP is not aware of the root-leaf topology either, root ports may end up blocked before leaf interfaces.

  • When xSTP is used as an access redundancy mechanism, Nokia recommends connecting the dual-homed device to the same type of E-Tree AC, to avoid unexpected forwarding behaviors when xSTP converges.

• Redundancy mechanisms such as MC-LAG, SDP bind end-points, or BGP-MH are fully supported on VPLS E-Tree services. However, eth-tunnel SAPs or eth-ring control SAPs are not supported on VPLS E-Tree services.

Use the following CLI syntax to create a VPLS service.

CLI syntax:

config>service# vpls service-id [customer customer-id] [vpn vpn-id] [m-vpls] [b-vpls | i-vpls] [create]
      description description-string
      no shutdown

The following example shows a VPLS configuration:

*A:ALA-1>config>service>vpls# info
----------------------------------------------
...
        vpls 9000 customer 6 create
            description "This is a distributed VPLS."
            stp
                shutdown
            exit
        exit
...
----------------------------------------------
*A:ALA-1>config>service>vpls#

When the Multiple MAC Registration Protocol (MMRP) is enabled in the B-VPLS, it advertises the presence of the I-VPLS instances associated with this B-VPLS.

The following example shows a configuration with MMRP enabled.

*A:PE-B>config>service# info
----------------------------------------------
        vpls 11 customer 1 vpn 11 i-vpls create
            backbone-vpls 100:11
            exit
            stp
                shutdown
            exit
            sap 1/5/1:11 create
            exit
            sap 1/5/1:12 create
            exit
            no shutdown
        exit
        vpls 100 customer 1 vpn 100 b-vpls create
            service-mtu 2000
            stp
                shutdown
            exit
            mrp
                flood-time 10
                no shutdown
            exit
            sap 1/5/1:100 create
            exit
            spoke-sdp 3101:100 create
            exit
            spoke-sdp 3201:100 create
            exit
            no shutdown
        exit
----------------------------------------------
*A:PE-B>config>service# 

Because I-VPLS 11 is associated with B-VPLS 100, MMRP advertises the group B-MAC 01:1e:83:00:00:0b) associated with I-VPLS 11 through a declaration on all the B-SAPs and B-SDPs. If the remote node also declares an I-VPLS 11 associated with its B-VPLS 10, then this results in a registration for the group B-MAC. This also creates the MMRP multicast tree (MFIB entries). In this case, sdp 3201:100 is connected to a remote node that declares the group B-MAC.

The following show commands display the current MMRP information for this scenario:

*A:PE-C# show service id 100 mrp
-------------------------------------------------------------------------------
MRP Information
-------------------------------------------------------------------------------
Admin State        : Up                 Failed Register Cnt: 0
Max Attributes     : 1023               Attribute Count    : 1
Attr High Watermark: 95%                Attr Low Watermark : 90%
Flood Time         : 10
-------------------------------------------------------------------------------
*A:PE-C# show service id 100 mmrp mac
-------------------------------------------------------------------------------
SAP/SDP                                 MAC Address       Registered  Declared
-------------------------------------------------------------------------------
sap:1/5/1:100                           01:1e:83:00:00:0b No          Yes
sdp:3101:100                            01:1e:83:00:00:0b No          Yes
sdp:3201:100                            01:1e:83:00:00:0b Yes         Yes
-------------------------------------------------------------------------------


*A:PE-C# show service id 100 sdp 3201:100 mrp
-------------------------------------------------------------------------------
Sdp Id 3201:100 MRP Information
-------------------------------------------------------------------------------
Join Time          : 0.2 secs                 Leave Time        : 3.0 secs
Leave All Time     : 10.0 secs                Periodic Time     : 1.0 secs
Periodic Enabled   : false
Rx Pdus            : 7                        Tx Pdus           : 23
Dropped Pdus       : 0
Rx New Event       : 0                        Rx Join-In Event  : 6
Rx In Event        : 0                        Rx Join Empty Evt : 1
Rx Empty Event     : 0                        Rx Leave Event    : 0
Tx New Event       : 0                        Tx Join-In Event  : 4
Tx In Event        : 0                        Tx Join Empty Evt : 19
Tx Empty Event     : 0                        Tx Leave Event    : 0
-------------------------------------------------------------------------------
SDP MMRP Information
-------------------------------------------------------------------------------
MAC Address       Registered        Declared
-------------------------------------------------------------------------------
01:1e:83:00:00:0b Yes               Yes
-------------------------------------------------------------------------------
Number of MACs=1 Registered=1 Declared=1
-------------------------------------------------------------------------------
*A:PE-C#


*A:PE-C#  show service id 100 mfib
===============================================================================
Multicast FIB, Service 100
===============================================================================
Source Address  Group Address         Sap/Sdp Id               Svc Id   Fwd/Blk
-------------------------------------------------------------------------------
*               01:1E:83:00:00:0B     sdp:3201:100             Local    Fwd
-------------------------------------------------------------------------------
Number of entries: 1
===============================================================================
*A:PE-C#

The following parameters must be configured in order for GSMP to function:

• One or more GSMP sessions

• One or more ANCP policies

• For basic subscriber management only, ANCP static maps

• For enhanced subscriber management only, associate subscriber profiles with ANCP policies

Use the following CLI syntax to configure GSMP parameters.

CLI syntax:

config>service>vpls# gsmp
    — group name [create]
        — ancp
            — dynamic-topology-discover
            — oam
        — description description-string
        — hold-multiplier multiplier
        — keepalive seconds
        — neighbor ip-address [create]
            — description v
            — local-address ip-address
            — priority-marking dscp dscp-name
            — priority-marking prec ip-prec-value
            — [no] shutdown
        — [no] shutdown
    — [no] shutdown

This example shows a GSMP group configuration.

A:ALA-48>config>service>vpls>gsmp# info
----------------------------------------------
                group "group1" create
                    description "test group config"
                    neighbor 10.10.10.104 create
                        description "neighbor1 config"
                        local-address 10.10.10.103
                        no shutdown
                    exit
                    no shutdown
                exit
                no shutdown
----------------------------------------------
A:ALA-48>config>service>vpls>gsmp#

A default QoS policy is applied to each ingress and egress SAP. Additional QoS policies can be configured in the config>qos context. There are no default filter policies. Filter policies are configured in the config>filter context and must be explicitly applied to a SAP.

See the following sections to configure local and distributed VPLS SAPs.

• Local VPLS SAPs
• Distributed VPLS SAPs

Use the following CLI syntax to configure subscriber management parameters on a VPLS service SAP on the 7450 ESS and 7750 SR. The policies and profiles that are referenced in the def-sla-profile, def-sub-profile, non-sub-traffic, and sub-ident-policy commands must already be configured in the config>subscr-mgmt context.

CLI syntax:

config>service>vpls service-id 
    — sap sap-id [split-horizon-group group-name]
        — sub-sla-mgmt
            — def-sla-profile default-sla-profile-name
            — def-sub-profile default-subscriber-profile-name
            — mac-da-hashing
            — multi-sub-sap [number-of-sub]
            — no shutdown
            — single-sub-parameters
                — non-sub-traffic sub-profile sub-profile-name sla-profile sla-profile-name [subscriber sub-ident-string]
                — profiled-traffic-only
            — sub-ident-policy sub-ident-policy-name

The following example shows a subscriber management configuration:

A:ALA-48>config>service>vpls#
----------------------------------------------
            description "Local VPLS"
            stp
                shutdown
            exit
            sap 1/2/2:0 create
                description "SAP for local service"
                sub-sla-mgmt
                    def-sla-profile "sla-profile1"
                    sub-ident-policy "SubIdent1"
                exit
            exit
            sap 1/1/5:0 create
                description "SAP for local service"
            exit
            no shutdown
----------------------------------------------
A:ALA-48>config>service>vpls#

When MSTP is used to control VLANs, a range of VLAN IDs is normally used to specify the VLANs to be controlled on the 7450 ESS and 7750 SR.

If an Ethernet tunnel SAP is to be controlled by MSTP, the Ethernet tunnel SAP ID needs to be within the VLAN range specified under the mst-instance.

vpls 400 customer 1 m-vpls create
            stp
                mode mstp
                mst-instance 111 create
                    vlan-range 1-100
                exit
                mst-name "abc"
                mst-revision 1
                no shutdown
            exit
            sap 1/1/1:0 create // untagged
            exit
            sap eth-tunnel-1 create
            exit
            no shutdown
        exit
        vpls 401 customer 1 create
            stp
                shutdown
            exit
            sap 1/1/1:12 create
            exit
            sap eth-tunnel-1:12 create
                // Ethernet tunnel SAP ID 12 falls within the VLAN
                // range for mst-instance 111
                eth-tunnel
                    path 1 tag 1000
                    path 8 tag 2000
                exit
            exit
            no shutdown
        exit

VPLS provides scaling and operational advantages. A hierarchical configuration eliminates the need for a full mesh of VCs between participating devices. Hierarchy is achieved by enhancing the base VPLS core mesh of VCs with access VCs (spoke) to form two tiers. Spoke SDPs are generally created between Layer 2 switches and placed at the MTU. The PE routers are placed at the service provider's Point of Presence (POP). Signaling and replication overhead on all devices is considerably reduced.

A spoke SDP is treated like the equivalent of a traditional bridge port where flooded traffic received on the spoke SDP is replicated on all other ‟ports” (other spoke and mesh SDPs or SAPs) and not transmitted on the port it was received (unless a split horizon group was defined on the spoke SDP; see section Configuring VPLS spoke SDPs with split horizon).

A spoke SDP connects a VPLS service between two sites and, in its simplest form, could be a single tunnel LSP. A set of ingress and egress VC labels are exchanged for each VPLS service instance to be transported over this LSP. The PE routers at each end treat this as a virtual spoke connection for the VPLS service in the same way as the PE-MTU connections. This architecture minimizes the signaling overhead and avoids a full mesh of VCs and LSPs between the two metro networks.

A mesh SDP bound to a service is logically treated like a single bridge ‟port” for flooded traffic where flooded traffic received on any mesh SDP on the service is replicated to other ‟ports” (spoke SDPs and SAPs) and not transmitted on any mesh SDPs.

A VC-ID can be specified with the SDP-ID. The VC-ID is used instead of a label to identify a virtual circuit. The VC-ID is significant between peer SRs on the same hierarchical level. The value of a VC-ID is conceptually independent from the value of the label or any other datalink-specific information of the VC.

SDPs — unidirectional tunnels shows an example of a distributed VPLS service configuration of spoke and mesh SDPs (unidirectional tunnels) between routers and MTUs.

The following output shows a service SAP queue override configuration example:

*A:ALA-48>config>service>vpls>sap# info
----------------------------------------------
...
exit
ingress
    scheduler-policy "SLA1"
    scheduler-override
        scheduler "sched1" create
            parent weight 3 cir-weight 3
        exit
    exit
    policer-control-policy "SLA1-p"
    policer-control-override create
        max-rate 50000
    exit
    qos 100 multipoint-shared
    queue-override
        queue 1 create
            rate 1500000 cir 2000
        exit
    exit
    policer-override
        policer 1 create
            rate 10000
        exit
    exit
exit
egress
    scheduler-policy "SLA1"
    policer-control-policy "SLA1-p"
    policer-control-override create
        max-rate 60000
    exit
    qos 100
    queue-override
        queue 1 create
            adaptation-rule pir max cir max
        exit
    exit
    policer-override
        policer 1 create
            mbs 2000 kilobytes
        exit
    exit
    filter ip 10
exit
----------------------------------------------
*A:ALA-48>config>service>vpls>sap#

Use the following CLI syntax to create mesh or spoke-SDP bindings with a distributed VPLS service. SDPs must be configured before binding. For information about creating SDPs, see the 7450 ESS, 7750 SR, 7950 XRS, and VSR Services Overview Guide.

Use the following CLI syntax to configure mesh SDP bindings.

CLI syntax:

config>service# vpls service-id 
    — mesh-sdp sdp-id[:vc-id] [vc-type {ether | vlan}]
        — egress
            — filter {ip ip-filter-id|mac mac-filter-id}
            — mfib-allowed-mda-destinations
                    — mda mda-id
            — vc-label egress-vc-label
        — ingress
            — filter {ip ip-filter-id|mac mac-filter-id}
            — vc-label ingress-vc-label
        — no shutdown
        — static-mac ieee-address
        — vlan-vc-tag 0..4094

Use the following CLI syntax to configure spoke-SDP bindings.

CLI syntax:

config>service# vpls service-id 
    — spoke-sdp sdp-id:vc-id [vc-type {ether | vlan}] [split-horizon-group group-name] 
        — egress
            — filter {ip ip-filter-id|mac mac-filter-id}
            — vc-label egress-vc-label
        — ingress
            — filter {ip ip-filter-id|mac mac-filter-id}
            — vc-label ingress-vc-label
        — limit-mac-move[non-blockable]
        — vlan-vc-tag 0..4094
        — no shutdown
        — static-mac ieee-address
        — stp
            — path-cost stp-path-cost
            — priority stp-priority
            — no shutdown
        — vlan-vc-tag [0..4094]

The following examples show SDP binding configurations for ALA-1, ALA-2, and ALA-3 for VPLS service ID 9000 for customer 6:

*A:ALA-1>config>service# info
----------------------------------------------
...
        vpls 9000 customer 6 create
            description "This is a distributed VPLS."
            stp
                shutdown
            exit
            sap 1/2/5:0 create
            exit
            spoke-sdp 2:22 create
            exit
            mesh-sdp 5:750 create
            exit
            mesh-sdp 7:750 create
            exit
            no shutdown
        exit
----------------------------------------------
*A:ALA-1>config>service#


*A:ALA-2>config>service# info
----------------------------------------------
...
        vpls 9000 customer 6 create
            description "This is a distributed VPLS."
            stp
                shutdown
            exit
            sap 1/1/2:22 create
            exit
            spoke-sdp 2:22 create
            exit
            mesh-sdp 5:750 create
            exit
            mesh-sdp 7:750 create
            exit
            no shutdown
        exit
----------------------------------------------


*A:ALA-3>config>service# info
----------------------------------------------
...
        vpls 9000 customer 6 create
            description "This is a distributed VPLS."
            stp
                shutdown
            exit
            sap 1/1/3:33 create
            exit
            spoke-sdp 2:22 create
            exit
            mesh-sdp 5:750 create
            exit
            mesh-sdp 7:750 create
            exit
            no shutdown
        exit
----------------------------------------------
*A:ALA-3>config>service#

This section provides a brief overview of the tasks that must be performed to configure a management VPLS for SAP protection and provides the CLI commands; see Example configuration for protected VPLS SAP. The following tasks should be performed on both nodes providing the protected VPLS service.

Before configuring a management VPLS, read VPLS redundancy for an introduction to the concept of management VPLS and SAP redundancy.

1. Create an SDP to the peer node.

2. Create a management VPLS.

3. Define a SAP in the M-VPLS on the port toward the MTU. The port must be dot1q or QinQ tagged. The SAP corresponds to the (stacked) VLAN on the MTU in which STP is active.

4. Optionally, modify STP parameters for load balancing.

5. Create a mesh SDP in the M-VPLS using the SDP defined in step 1. Ensure that this mesh SDP runs over a protected LSP.

6. Enable the management VPLS service and verify that it is operationally up.

7. Create a list of VLANs on the port that are to be managed by this management VPLS.

8. Create one or more user VPLS services with SAPs on VLANs in the range defined in step 6.

   Note: The mesh SDP should be protected by a backup LSP or Fast Reroute. If the mesh SDP went down, STP on both nodes would go to forwarding state and a loop would occur.

Use the following CLI syntax to create a management VPLS on the 7450 ESS or 7750 SR.

config>service# sdp sdp-id mpls create
    — far-end ip-address
    — lsp lsp-name
    — no shutdown

vpls service-id customer customer-id [m-vpls] create
    — description description-string
    — sap sap-id create
        — managed-vlan-list
            — range vlan-range
    — mesh-sdp sdp-id:vc-id create
    — stp
    — no shutdown

*A:ALA-1>config>service# info
----------------------------------------------
...
       sdp 300 mpls create
            far-end 10.0.0.20
            lsp "toALA-A2"
            no shutdown
       exit
       vpls 1 customer 1 m-vpls create
            sap 1/1/1:1 create
                managed-vlan-list
                    range 100-1000
                exit
            exit
            mesh-sdp 300:1 create
            exit
            stp
            exit
            no shutdown
        exit
...
----------------------------------------------
*A:ALA-1>config>service#

With the concept of management VPLS, it is possible to load balance the user VPLS services across the two protecting nodes. This is done by creating two management VPLS instances, where both instances have different active QinQ spokes (by changing the STP path-cost). When user VPLS services are associated with either of the two management VPLS services, the traffic is split across the two QinQ spokes. Load balancing can be achieved in both the SAP protection and spoke-SDP protection scenarios.

Example configuration for load balancing across two protected VPLS spoke-SDPs shows an example configuration for load balancing across two protected VPLS spoke-SDPs.

Use the following CLI syntax to create load balancing across two management VPLS instances.

CLI syntax:

config>service# sdp sdp-id mpls create
far-end ip-address
lsp lsp-name
no shutdown

CLI syntax:

vpls service-id customer customer-id [m-vpls] create
    — description description-string
    — mesh-sdp sdp-id:vc-id create
    — spoke-sdp sdp-id:vc-id create
        — stp
            — path-cost 
    — stp
    — no shutdown

The following example shows the VPLS configuration on ALA-A1 (upper left, IP address 10.0.0.10):

*A:ALA-A1>config>service# info
----------------------------------------------
...
      sdp 101 mpls create
            far-end 10.0.0.30
            lsp "1toALA-B1"
            no shutdown
      exit
      sdp 102 mpls create
            far-end 10.0.0.30
            lsp "2toALA-B1"
            no shutdown
      exit
 ...
     vpls 101 customer 1 m-vpls create
            spoke-sdp 101:1 create
               stp
                  path-cost 1
               exit
            exit
            mesh-sdp 300:1 create
            exit
            stp
            exit
           no shutdown
      exit
      vpls 102 customer 1 m-vpls create
            spoke-sdp 102:2 create
               stp
                  path-cost 1000
               exit
            exit
            mesh-sdp 300:2 create
            exit
            stp
            exit
            no shutdown
      exit
...
----------------------------------------------
*A:ALA-A1>config>service#

The following example shows the VPLS configuration on ALA-A2 (lower left, IP address 10.0.0.20):

*A:ALA-A2>config>service# info
----------------------------------------------
...
      sdp 101 mpls create
            far-end 10.0.0.40
            lsp "1toALA-B2"
            no shutdown
      exit
      sdp 102 mpls create
            far-end 10.0.0.40
            lsp "2toALA-B2"
            no shutdown
      exit
 ...
     vpls 101 customer 1 m-vpls create
            spoke-sdp 101:1 create
               stp
                  path-cost 1000
               exit
            exit
            mesh-sdp 300:1 create
            exit
            stp
            exit
           no shutdown
      exit
      vpls 102 customer 1 m-vpls create
            spoke-sdp 102:2 create
               stp
                  path-cost 1
               exit
            exit
            mesh-sdp 300:2 create
            exit
            stp
            exit
            no shutdown
      exit
...
----------------------------------------------
*A:ALA-A2>config>service#

The following example shows the VPLS configuration on ALA-A3 (upper right, IP address 10.0.0.30):

*A:ALA-A1>config>service# info
----------------------------------------------
...
      sdp 101 mpls create
            far-end 10.0.0.10
            lsp "1toALA-A1"
            no shutdown
      exit
      sdp 102 mpls create
            far-end 10.0.0.10
            lsp "2toALA-A1"
            no shutdown
      exit
 ...
     vpls 101 customer 1 m-vpls create
            spoke-sdp 101:1 create
               stp
                  path-cost 1
               exit
            exit
            mesh-sdp 300:1 create
            exit
            stp
            exit
            no shutdown
      exit
      vpls 102 customer 1 m-vpls create
            spoke-sdp 102:2 create
               stp
                  path-cost 1000
               exit
            exit
            mesh-sdp 300:2 create
            exit
            stp
            exit
            no shutdown
      exit
...
----------------------------------------------
*A:ALA-A1>config>service#

The following example shows the VPLS configuration on ALA-A4 (lower right, IP address 10.0.0.40):

*A:ALA-A2>config>service# info
----------------------------------------------
...
      sdp 101 mpls create
            far-end 10.0.0.20
            lsp "1toALA-B2"
            no shutdown
      exit
      sdp 102 mpls create
            far-end 10.0.0.20
            lsp "2toALA-B2"
            no shutdown
      exit
 ...
     vpls 101 customer 1 m-vpls create
            spoke-sdp 101:1 create
               stp
                  path-cost 1000
               exit
            exit
            mesh-sdp 300:1 create
            exit
            stp
            exit
            no shutdown
      exit
      vpls 102 customer 1 m-vpls create
            spoke-sdp 102:2 create
               stp
                  path-cost 1
               exit
            exit
            mesh-sdp 300:2 create
            exit
            stp
            exit
            no shutdown
      exit
...
----------------------------------------------
*A:ALA-A2>config>service#

Use the following CLI syntax to enable selective MAC flush in a VPLS.

config>service# vpls service-id 
    — send-flush-on-failure

Use the following CLI syntax to disable selective MAC flush in a VPLS.

config>service# vpls service-id 
    — no send-flush-on-failure

The following output shows configuration examples of multichassis redundancy and the VPLS configuration. The configurations in the graphics depicted in Inter-domain VPLS resiliency using multichassis endpoints are represented in this output.

Node mapping to the following examples in this section:

• PE3 = Dut-B

• PE3' = Dut-C

• PE1 = Dut-D

• PE2 = Dut-E

PE3 Dut-B

*A:Dut-B>config>redundancy>multi-chassis# info 
----------------------------------------------
            peer 10.1.1.3 create
                peer-name "Dut-C"
                description "mcep-basic-tests"
                source-address 10.1.1.2
                mc-endpoint
                    no shutdown
                    bfd-enable
                    system-priority 50
                exit
                no shutdown
            exit 
----------------------------------------------
*A:Dut-B>config>redundancy>multi-chassis#


*A:Dut-B>config>service>vpls# info 
----------------------------------------------
            fdb-table-size 20000
            send-flush-on-failure
            stp
                shutdown
            exit
            endpoint "mcep-t1" create
                no suppress-standby-signaling
                block-on-mesh-failure
                mc-endpoint 1
                    mc-ep-peer Dut-C
                exit
            exit
            mesh-sdp 201:1 vc-type vlan create
            exit
            mesh-sdp 211:1 vc-type vlan create
            exit
            spoke-sdp 221:1 vc-type vlan endpoint "mcep-t1" create
                stp
                    shutdown
                exit
                block-on-mesh-failure
                precedence 1          
            exit
            spoke-sdp 231:1 vc-type vlan endpoint "mcep-t1" create
                stp
                    shutdown
                exit
                block-on-mesh-failure
                precedence 2
            exit
            no shutdown
----------------------------------------------
*A:Dut-B>config>service>vpls#

PE3' Dut-C

:Dut-C>config>redundancy>multi-chassis# info 
----------------------------------------------
            peer 10.1.1.2 create
                peer-name "Dut-B"
                description "mcep-basic-tests"
                source-address 10.1.1.3
                mc-endpoint
                    no shutdown
                    bfd-enable
                    system-priority 21
                exit
                no shutdown
            exit 
----------------------------------------------
*A:Dut-C>config>redundancy>multi-chassis# 

*A:Dut-C>config>service>vpls# info 
----------------------------------------------
            fdb-table-size 20000
            send-flush-on-failure
            stp
                shutdown
            exit
            endpoint "mcep-t1" create
                no suppress-standby-signaling
                block-on-mesh-failure
                mc-endpoint 1
                    mc-ep-peer Dut-B
                exit
            exit
            mesh-sdp 301:1 vc-type vlan create
            exit
            mesh-sdp 311:1 vc-type vlan create
            exit
            spoke-sdp 321:1 vc-type vlan endpoint "mcep-t1" create
                stp
                    shutdown
                exit
                block-on-mesh-failure
                precedence 3
            exit
            spoke-sdp 331:1 vc-type vlan endpoint "mcep-t1" create
                stp
                    shutdown
                exit
                block-on-mesh-failure
            exit
            no shutdown
----------------------------------------------
*A:Dut-C>config>service>vpls# 

PE1 Dut-D

*A:Dut-D>config>redundancy>multi-chassis# info 
----------------------------------------------
            peer 10.1.1.5 create
                peer-name "Dut-E"
                description "mcep-basic-tests"
                source-address 10.1.1.4
                mc-endpoint
                    no shutdown
                    bfd-enable
                    system-priority 50
                    passive-mode
                exit
                no shutdown
            exit 
----------------------------------------------
*A:Dut-D>config>redundancy>multi-chassis# 

*A:Dut-D>config>service>vpls# info 
----------------------------------------------
            fdb-table-size 20000
            propagate-mac-flush
            stp
                shutdown
            exit
            endpoint "mcep-t1" create
                block-on-mesh-failure
                mc-endpoint 1
                    mc-ep-peer Dut-E
                exit
            exit
            mesh-sdp 401:1 vc-type vlan create
            exit
            spoke-sdp 411:1 vc-type vlan endpoint "mcep-t1" create
                stp
                    shutdown
                exit
                block-on-mesh-failure
                precedence 2
            exit
            spoke-sdp 421:1 vc-type vlan endpoint "mcep-t1" create
                stp
                    shutdown
                exit
                block-on-mesh-failure
                precedence 1
            exit
            mesh-sdp 431:1 vc-type vlan create
            exit
            no shutdown
----------------------------------------------
*A:Dut-D>config>service>vpls# 

PE2 Dut-E

*A:Dut-E>config>redundancy>multi-chassis# info 
----------------------------------------------
            peer 10.1.1.4 create
                peer-name "Dut-D"
                description "mcep-basic-tests"
                source-address 10.1.1.5
                mc-endpoint
                    no shutdown
                    bfd-enable
                    system-priority 22
                    passive-mode
                exit
                no shutdown
            exit 
----------------------------------------------
*A:Dut-E>config>redundancy>multi-chassis#  

*A:Dut-E>config>service>vpls# info 
----------------------------------------------
            fdb-table-size 20000
            propagate-mac-flush
            stp
                shutdown
            exit
            endpoint "mcep-t1" create
                block-on-mesh-failure
                mc-endpoint 1
                    mc-ep-peer Dut-D
                exit
            exit
            spoke-sdp 501:1 vc-type vlan endpoint "mcep-t1" create
                stp
                    shutdown
                exit
                block-on-mesh-failure
                precedence 3
            exit
            spoke-sdp 511:1 vc-type vlan endpoint "mcep-t1" create
                stp
                    shutdown
                exit
                block-on-mesh-failure
            exit
            mesh-sdp 521:1 vc-type vlan create
            exit
            mesh-sdp 531:1 vc-type vlan create
            exit
            no shutdown
----------------------------------------------
*A:Dut-E>config>service>vpls# 

Using BGP AD configuration example, assume PE6 was previously configured with VPLS 100 as indicated by the configurations code in the upper right. The BGP AD process commences after PE134 is configured with the VPLS 100 instance, as shown in the upper left. This shows a basic BGP AD configuration. The minimum requirement for enabling BGP AD on a VPLS instance is configuring the VPLS-ID and pointing to a pseudowire template.

In many cases, VPLS connectivity is based on a pseudowire mesh. To reduce the configuration requirement, the BGP values can be automatically generated using the VPLS-ID and the MPLS router-ID. By default, the lower six bytes of the VPLS-ID are used to generate the RD and the RT values. The VSI-ID value is generated from the MPLS router-ID. All of these parameters are configurable and can be coded to suit requirements and build different topologies.

PE134>config>service>vpls>bgp-ad#
[no] shutdown - Administratively enable/disable BGP auto-discovery
vpls-id - Configure VPLS-ID
vsi-id + Configure VSI-id

The following command displays the service information, the BGP parameters, and the SDP bindings in use. When the discovery process is completed successfully, each endpoint has an entry for the service.

show service l2-route-table

PE134># show service l2-route-table 
=======================================================================
Services: L2 Route Information - Summary Service
=======================================================================
Svc Id     L2-Routes (RD-Prefix)                 Next Hop        Origin
               Sdp Bind Id
-----------------------------------------------------------------------
100        65535:100-1.1.1.6                     1.1.1.6         BGP-L2
               17406:4294967295
-----------------------------------------------------------------------
No. of L2 Route Entries: 1 
=======================================================================
PERs6>#

PERs6># show service l2-route-table
=======================================================================
Services: L2 Route Information - Summary Service
=======================================================================
Svc Id     L2-Routes (RD-Prefix)                 Next Hop        Origin
               Sdp Bind Id
-----------------------------------------------------------------------
100        65535:100-1.1.1.134                   1.1.1.134       BGP-L2
               17406:4294967295
-----------------------------------------------------------------------
No. of L2 Route Entries: 1
=======================================================================
PERs6>#

When only one of the endpoints has an entry for the service in the l2-routing-table, it is most likely a problem with the RT values used for import and export. This would most likely happen when different import and export RT values are configured using a router policy or the route-target command.

Service-specific commands continue to be available to display service-specific information, including status:

show service sdp-using

PERs6# show service sdp-using
===============================================================================
SDP Using
===============================================================================
SvcId       SdpId               Type    Far End        Opr S* I.Label  E.Label
-------------------------------------------------------------------------------
100         17406:4294967295    BgpAd   10.1.1.134      Up     131063   131067
-------------------------------------------------------------------------------
Number of SDPs : 1
===============================================================================
* indicates that the corresponding row element may have been truncated.

BGP AD advertises the VPLS-ID in the extended community attribute, VSI-ID in the NLRI, and the local PE ID in the BGP next hop. At the receiving PE, the VPLS-ID is compared against locally provisioned information to determine whether the two PEs share a common VPLS. If they do, the BGP information is used in the signaling phase (see Configuring BGP VPLS).

T-LDP is triggered when the VPN endpoints have been discovered using BGP. The T-LDP session between the PEs is established when a session does not exist. The far-end IP address required for the T-LDP identification is learned from the BGP AD next hop information. The pw-template and pw-template-binding configuration statements are used to establish the automatic SDP or to map to the appropriate SDP. The FEC129 content is built using the following values:

• AGI from the locally configured VPLS-ID

• SAII from the locally configured VSI-ID

• TAII from the VSI-ID contained in the last 4 bytes of the received BGP NLRI

BGP AD triggering LDP functions shows the different detailed phases of the LDP signaling path, post BGP AD completion. It also indicates how some fields can be auto-generated when they are not specified in the configuration.

The following command shows the LDP peering relationships that have been established (see Show router LDP session output). The type of adjacency is displayed in the ‟Adj Type” column. In this case, the type is ‟Both” meaning link and targeted sessions have been successfully established.

The following command shows the specific LDP service label information broken up per FEC element type: 128 or 129, basis (see Show router LDP bindings FEC-type services). The information for FEC element 129 includes the AGI, SAII, and the TAII.

The pseudowire template is defined under the top-level service command (config>service>pw-template) and specifies whether to use an automatically generated SDP or manually configured SDP. It also provides the set of parameters required for establishing the pseudowire (SDP binding) as follows:

PERs6>config>service# pw-template 1 create
 -[no] pw-template <policy-id> [use-provisioned-sdp | prefer-provisioned-sdp]
<policy-id> : [1..2147483647]
<use-provisioned-s*> : keyword
<prefer-provisioned*> : keyword


[no] accounting-pol*    - Configure accounting-policy to be used
[no] auto-learn-mac*    - Enable/Disable automatic update of MAC protect list
[no] block-on-peer-*    - Enable/Disable block traffic on peer fault
[no] collect-stats      - Enable/disable statistics collection
[no] control word       - Enable/Disable the use of Control Word
[no] disable-aging      - Enable/disable aging of MAC addresses
[no] disable-learni*    - Enable/disable learning of new MAC addresses
[no] discard-unknow*    - Enable/disable discarding of frames with unknown source
                          MAC address
     egress             + Spoke SDP binding egress configuration
[no] force-qinq-vc-*    - Forces qinq-vc-type forwarding in the data-path
[no] force-vlan-vc-*    - Forces vlan-vc-type forwarding in the data-path
[no] hash-label         - Enable/disable use of hash-label
     igmp-snooping      + Configure IGMP snooping parameters
     ingress            + Spoke SDP binding ingress configuration
[no] l2pt-terminati*    - Configure L2PT termination on this spoke SDP
[no] limit-mac-move     - Configure mac move
[no] mac-pinning        - Enable/disable MAC address pinning on this spoke SDP
[no] max-nbr-mac-ad*    - Configure the maximum number of MAC entries in the FDB
                          from this SDP
[no] restrict-prote*    - Enable/disable protected src MAC restriction
[no] sdp-exclude        - Configure excluded SDP group
[no] sdp-include        - Configure included SDP group
[no] split-horizon-*    + Configure a split horizon group
     stp                + Configure STP parameters
     vc-type            - Configure VC type
[no] vlan-vc-tag        - Configure VLAN VC tag

A pw-template-binding command configured within the VPLS service under the bgp-ad sub-command is a pointer to the pw-template that should be used. If a VPLS service does not specify an import-rt list, then that binding applies to all route targets accepted by that VPLS. The pw-template-bind command can select a different template on a per import-rt basis. It is also possible to specify specific pw-templates for some route targets with a VPLS service and use the single pw-template-binding command to address all unspecified but accepted imported targets.

It is important to understand the significance of the split horizon group used by the pw-template. Traditionally, when a VPLS instance was manually created using mesh-SDP bindings, these were automatically placed in a common split horizon group to prevent forwarding between the pseudowire in the VPLS instances. This prevents loops that would have otherwise occurred in the Layer 2 service. When automatically discovering VPLS service using BGP AD, the service provider has the option of associating the auto-discovered pseudowire with a split horizon group to control the forwarding between pseudowires.

Use the following CLI syntax to create a VPLS management interface:

CLI syntax:

    config>service>vpls# interface ip-int-name
    address ip-address[/mask] [netmask]
    arp-timeout seconds
    description description-string
    mac ieee-address
    no shutdown
    static-arp ip-address ieee-address

The following example shows the configuration.

A:ALA-49>config>service>vpls>interface# info detail
---------------------------------------------
               no description
               mac 14:31:ff:00:00:00
               address 10.231.10.10/24
               no arp-timeout
               no shutdown
---------------------------------------------
A:ALA-49>config>service>vpls>interface#