Chapter 9 High Availability for FortiOS 5.0 : Full mesh HA : Full mesh HA overview : Full mesh HA and redundant heartbeat interfaces
  
Full mesh HA and redundant heartbeat interfaces
A full mesh HA configuration also includes redundant HA heartbeat interfaces. At least two heartbeat interfaces should be selected in the HA configuration and both sets of HA heartbeat interfaces should be connected. The HA heartbeat interfaces do not have to be configured as redundant interfaces because the FGCP handles failover between heartbeat interfaces.