Configure SNMP Traps/Informs When Using Cisco VRF-Lite

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Notes

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No VRF-Lite specific configuration is required for SNMP polling; VRF-Lite configuration is only required for trap and inform related (outbound) communications.

This configuration is not required if SNMP can operate using 'global' (non-VRF) router resources (i.e. interfaces and routes not assigned to a VRF.)

This configuration applies to SNMP v1 and v2 use only.

You can specify any VRF, as long as that VRF has a path to the trap or inform destination host.

You may not be able to configure distinct SNMP trap/inform destinations per VRF as only one trap/inform source interface can be specified; each VRF and the external networks/devices related to it on the path to the destination must have a return route to the specified source interface if this is to work. For this reason it may, in some environments, be preferable to use global router resources for all SNMP related functions.

Configuration Tasks

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To configure SNMP operation for VRF-Lite awareness, where VRF resources (interfaces, routes, etc) will be used by SNMP use these commands;

Configuration Context: font color=purpleGlobal Configuration/font

• Configure interface index persistence, if required: snmp ifmib ifindex persist

• Configure SNMP trap authentication, if required: snmp-server trap authentication vrf

• Configure one or more trap destinations, specifying the VRF that will be used to reach the destination: snmp-server host ip_address vrf vrf_name traps community_string acl_number/name

• Configure one or more inform destinations, if required, specifying the VRF that will be used to reach the destination: snmp-server host ip_address vrf vrf_name inform community_string acl_number/name

• Configure a trap/inform source interface, which must be in one of the VRF specified above: snmp-server trap-source interface_name/number

Verification

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Use the show snmp host command to verify your configuration;

Notification host: 1.2.3.20        udp-port: 162   VRFName: v500   type: trap
user: public         security model: v1
traps: FFFFFFFF.FFFFFFFF.FFFFFFFF

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