Configuring SNMP

The sysName OID is located within the SNMP MIB-2 subtree, specifically at 1.3.6.1.2.1.1.5. This is generally the device FQDN. The SR Linux device reads the sysName from the configured system host name.

If the host name does not contain a dot (.) character, the configured domain name is also read, and is appended to the host name before being returned to the client.

The sysObjectId is located within the SNMP MIB-2 subtree, specifically at 1.3.6.1.2.1.1.2. This identifies the kind of device being managed. SR Linux uses the subtree at 1.3.6.1.4.1.6527.

The sysContact OID is located within the SNMP MIB-2 subtree, specifically at 1.3.6.1.2.1.1.4. This identifies the contact person for this managed node, together with information about how to contact this person. SR Linux propagates the information configured for /system/information/contact for the sysContact OID.

The sysLocation OID is located within the SNMP MIB-2 subtree, specifically at 1.3.6.1.2.1.1.6. This identifies the physical location of the device. SR Linux propagates the information configured for /system/information/location for the sysLocation OID.

The sysDescr OID is located within the SNMP MIB-2 subtree, specifically at 1.3.6.1.2.1.1.1. This value can include the name and version for the system hardware, software operating system, and networking software. This must contain only printable ASCII characters.

The SR Linux uses a fixed sysDescr field, based on this template:

<SRLinux-version (from IDB)> Nokia <Platform Type> right (c) 2000-2019 Nokia.
Kernel <kernel-version> <Linux-version> <SNMP-version> <kernel build date>.
All rights reserved. All use subject to applicable license agreements.

The ifIndex is located within the SNMP IF-MIB ifEntry subtree, specifically at 1.3.6.1.2.1.2.2.1.1. This is a unique value, greater than zero, for each interface. SR Linux propagates the /interface[]/ifindex leaf into the ifIndex OID. One ifEntry is created for each ifIndex found in the system. If an interface does not have an ifIndex, it is not populated into SNMP. An ifIndex is generated only for physical interfaces (excluding management).

The ifDescr OID is located within the SNMP IF-MIB ifEntry subtree, specifically at 1.3.6.1.2.1.2.2.1.2. This is a string containing information about the interface. This string can include the name of the manufacturer, product name, and version of the interface hardware/software. SR Linux propagates the /interface[]/description leaf into the ifDescr OID. If the description passed from /interface[]/description exceeds 255 characters, it is truncated.

The ifOperStatus OID is located within the SNMP IF-MIB ifEntry subtree, specifically at 1.3.6.1.2.1.2.2.1.8. This indicates the current operational state of the interface. SR Linux propagates the /interface[]/oper-state leaf into the ifOperStatus OID using the mapping shown in the following table.

The ifAdminStatus is located within the SNMP IF-MIB ifEntry subtree, specifically at 1.3.6.1.2.1.2.2.1.7. This is the desired state of the interface. The testing (3) state indicates that no operational packets can be passed. When a managed system initializes, all interfaces start with ifAdminStatus in the down (2) state. Based on either explicit management action or configuration information retained by the managed system, ifAdminStatus is then changed to either the up (1) or testing (3) states (or remains in the down(2) state).

SR Linux propagates the /interface[]/admin-state leaf into the ifAdminStatus OID using the mapping shown in the following table.

The ifType OID is located within the SNMP IF-MIB ifEntry subtree, specifically at 1.3.6.1.2.1.2.2.1.3. This indicates the type of interface. SR Linux propagates the ifType based on the interface name using the mapping shown in the following table.

The ifMtu is located within the SNMP IF-MIB ifEntry subtree, specifically at 1.3.6.1.2.1.2.2.1.4. This indicates the size of the largest packet that can be sent/received on the interface, specified in octets.

When used with Ethernet/bridged interfaces, this includes Ethernet overhead, but does not include the 4-byte FCS. When used with routed interfaces, this includes the IP header, but excludes any Ethernet encapsulation.

SR Linux propagates the /interface[]/mtu leaf into the ifMtu OID when dealing with physical or top level interfaces. For subinterfaces, the /interface[]/subinterface[]/l2-mtu should be used for type=bridged, and /interface[]/subinterface[]/l3-mtu should be used for type=routed.

The ifSpeed OID is located within the SNMP IF-MIB ifEntry subtree, specifically at 1.3.6.1.2.1.2.2.1.5. This is an estimate of the interface’s current bandwidth in bits per second. For interfaces that do not vary in bandwidth, or for those where no accurate estimation can be made, this object contains the nominal bandwidth.

If the bandwidth of the interface is greater than the maximum value reportable by this object, then this object reports its maximum value (4,294,967,295), and ifHighSpeed is used to report the interface’s speed using the mapping shown in the following table.

The ifPhysAddress OID is located within the SNMP IF-MIB ifEntry subtree, specifically at 1.3.6.1.2.1.2.2.1.6.

This is the interface address at its protocol sublayer. For example, for an 802.x interface, this object normally contains a MAC address. The interface’s media-specific MIB defines the bit and byte ordering and the format of the value of this object. For interfaces that do not have such an address (for example, a serial line), this object contains an octet string of zero length.

SR Linux propagates the /interface[]/ethernet/hw-mac-address leaf into the ifPhysAddress OID, with transformations to conform to the SNMPv2 IF-MIB. The transformations are to remove the ‟:” separators. For example, the MAC address 00:25:ba:51:c7:0a, is transformed into 0025ba51c70a. For subinterfaces, the parent interface MAC is used, and for any interfaces which do not use MAC addresses, the field contains an octet string of zero length.

The ifName OID is located within the SNMP IF-MIB2 ifXEntry subtree, specifically at 1.3.6.1.2.1.31.1.1.1.1.

This is the textual name of the interface. The value of this object is the name of the interface as assigned by the local device, and is suitable for use in commands entered at the device's console. This can be a text name, such as le0 or a simple port number, such as 1, depending on the interface naming syntax of the device. If several entries in the ifTable together represent a single interface as named by the device, then each has the same value of ifName. Note that for an agent that responds to SNMP queries concerning an interface on some other (proxied) device, then the value of ifName for such an interface is the proxied device’s local name for it.

If there is no local name, or this object is otherwise not applicable, then this object contains a zero-length string.

SR Linux propagates /interface[]/name (for physical or top-level interfaces) leaf or for subinterfaces the /interface[]/subinterface[]/name leaf into the ifName OID.

The ifHCInOctets OID is located within the SNMP IF-MIB2 ifXEntry subtree, specifically at 1.3.6.1.2.1.31.1.1.1.6.

This is the total number of octets received on the interface, including framing characters. This object is a 64-bit version of ifInOctets.

Discontinuities in the value of this counter can occur at reinitialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.

SR Linux propagates /interface[]/statistics/in-octets (for physical or top-level interfaces) leaf or for subinterfaces the /interface[]/subinterface[]/statistics/in-octets leaf into the ifHCInOctets OID.

The ifHCOutOctets OID is located within the SNMP IF-MIB2 ifXEntry subtree, specifically at 1.3.6.1.2.1.31.1.1.1.10.

This is the total number of octets transmitted out of the interface, including framing characters. This object is a 64-bit version of ifOutOctets.

Discontinuities in the value of this counter can occur at reinitialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.

SR Linux propagates /interface[]/statistics/out-octets (for physical or top-level interfaces) leaf, or for subinterfaces the /interface[]/subinterface[]/statistics/out-octets leaf, into the ifHCOutOctets OID.

The ifHighSpeed OID is located within the SNMP IF-MIB2 ifXEntry subtree, specifically at 1.3.6.1.2.1.31.1.1.1.15.

An estimate of the interfaces current bandwidth in units of 1,000,000 bits per second. If this object reports a value of `n then the speed of the interface is somewhere in the range of `n-500,000 to `n+499,999. For interfaces that do not vary in bandwidth, or for those where no accurate estimation can be made, this object contains the nominal bandwidth. For a sublayer that has no concept of bandwidth, this object is zero.

See Mapping between ifSpeed OID, ifHighSpeed, and port-speed leaf for the use of ifHighSpeed.

The ifPromiscuousMode is located within the SNMP IF-MIB2 ifXEntry subtree, specifically at 1.3.6.1.2.1.31.1.1.1.16.

This object has a value of false (2) if this interface only accepts packets/frames that are addressed to this station. This object has a value of true (1) when the station accepts all packets/frames transmitted on the media. The value true (1) is only legal for specific types of media. If legal, setting this object to a value of true (1) may require the interface to be reset before becoming effective.

The value of ifPromiscuousMode does not affect the reception of broadcast and multicast packets/frames by the interface.

This field is set to false (2) for all interfaces in SR Linux.

The ifConnectorPresent OID is located within the SNMP IF-MIB2 ifXEntry subtree, specifically at 1.3.6.1.2.1.31.1.1.1.17.

This object has the value true (1) if the interface sublayer has a physical connector and the value false (2) otherwise.

This field is set to false (2) for all non-physical interfaces. For physical interfaces with non-removable optics, this is set to true (1), and for physical interfaces with optics present, this is also set to true (1). A physical interface without an optic is set to false (2).

The ifAlias OID is located within the SNMP IF-MIB2 ifXEntry subtree, specifically at 1.3.6.1.2.1.31.1.1.1.18.

This object is an alias name for the interface as specified by a network manager, and provides a non-volatile identifier for the interface.

On the first instantiation of an interface, the value of ifAlias associated with that interface is the zero-length string. When a value is written into an instance of ifAlias through a network management set operation, the agent retains the supplied value in the ifAlias instance associated with the same interface for as long as that interface remains instantiated, including across all re-initializations/reboots of the network management system, including those that result in a change of the interface’s ifIndex value.

An example of the value that a network manager may store in this object for a WAN interface is the circuit number/identifier of the interface.

Some agents may support write access only for interfaces having particular values of ifType. An agent that supports write access to this object is required to keep the value in non-volatile storage, but it may limit the length of new values depending on how much storage is already occupied by the current values for other interfaces.

SR Linux propagates the /interface[]/description (for physical or top-level interfaces) leaf, or for subinterfaces the /interface[]/subinterface[]/description leaf, into the ifAlias OID.