Information
The administrator can configure SNMP to the interfaces source IP address for notifications
By using a source interface the administrator can ensure that the source IP of SNMP traps does not change as the network topology changes. For instance, if a link fails or is reconfigured, and a different IP address is now topologically "closer" to the SNMP trap server.There are a few typical candidates for an SNMP source IP address:
- A loopback address, as loopbacks are always up, and can then route over any transit interface.
- The MGMT 0 address, as that provides an out-of-band path to the SNMP server. SNMP traffic volume will not affect traffic volumes, and SNMP cannot be "starved" for bandwidth by production traffic. If the entire path is out-of-band, this also provides excellent protection from eavesdropping by malicious actors that may be on the "production data side" of the switch.
- A combination of the two (this is less common) - for instance a loopback address in the management VRF
Solution
switch(config)# snmp-server host 1.2.3.4 source-interface mgmt 0
or
switch(config)# snmp-server host 1.2.3.4 source-interface loopback 0
SNMP Server traps or informs:
switch(config)# snmp-server source-interface traps loopback 0
switch(config)# snmp-server source-interface informs loopback 0
or
switch(config)# snmp-server source-interface traps mgmt 0
switch(config)# snmp-server source-interface informs mgmt 0