Fortinet 5003 User Manual

In a single chassis, more than one cluster can use the same base backplane 
interface for HA heartbeat communication. To separate heartbeat communication 
for multiple clusters on the same base backplane interface, configure a different 
HA group name and password for each cluster. 

In a single chassis, you can also use the same base backplane interface for data 
and HA heartbeat communication. If you are operating multiple clusters and 
multiple data paths on the same base backplane interface you may experience 
some bandwidth limitations. To increase the amount of bandwidth available you 
can add a second FortiSwitch-5003 board and use both backplane interfaces for 
HA heartbeat and data communication. 

If you have two FortiSwitch-5003 boards and two backplane interfaces available 
you can balance the traffic between the base backplane interfaces by how you 
configure your FortiGate-5000 board data interfaces and HA heartbeat interfaces. 
For example, if you have two busy FortiGate-5001SX clusters you might configure 
one cluster to use port9 for HA heartbeat traffic and the other to use port10. If you 
have a number of data paths that use the same base backplane interfaces you 
can change the configuration to distribute traffic between both base backplane 
interfaces.