In a high-availability failover setting where SNMP monitoring of Messaging Server is desired, it is recommended that you run Messaging Server's SNMP subagent as a standalone agent as described in A.3.3 Running as a Standalone SNMP Agent. When the subagents are run in standalone mode, each HA instance of Messaging Server should have its local.snmp.listenaddr option set to the value of that instance's failover IP address. To simplify management, each instance should use the same UDP port, but that port should be distinct from those used by the snmpd daemons running on each of the physical cluster hosts. Typically those daemons will be using UDP port 161 so explicitly specify a different port number with the local.snmp.port option.
When Messaging Server's SNMP support is configured as recommended here, a monitoring station can monitor each instance of Messaging Server via its failover IP address or hostname regardless of which physical cluster host the instance is running on. Moreover, you are assured that Messaging Server's standalone SNMP agents will not conflict with one another as each listens only on its own virtual Ethernet interface identified by that instance's unique failover IP address. (These virtual Ethernet interfaces are automatically created by the HA failover framework.) Owing to the careful selection of a UDP port, the agents do not conflict with the snmpd daemons running on systems within the cluster.