Chapter 9 High Availability for FortiOS 5.0 : Operating a cluster : Clusters and SNMP
  
Clusters and SNMP
You can use SNMP to manage a cluster by configuring a cluster interface for SNMP administrative access. Using an SNMP manager you can get cluster configuration and status information and receive traps.
You configure SNMP for a cluster in the same way as configuring SNMP for a standalone FortiGate unit. SNMP configuration changes made to the cluster are shared by all cluster units.
Each cluster unit sends its own traps and SNMP manager systems can use SNMP get commands to query each cluster unit separately. To set SNMP get queries to each cluster unit you must create a special get command that includes the serial number of the cluster unit.
Alternatively you can use the HA reserved management interface feature to give each cluster unit a different management IP address. Then you can create an SNMP get command for each cluster unit that just includes the management IP address and does not have to include the serial number. See “Managing individual cluster units using a reserved management interface”.
For a list of HA MIB fields and OIDs, see “Fortinet MIBs”.