This FortiOS Handbook chapter contains the following sections:
Solving the High Availability problem describes the high availability problem and introduces the FortiOS solutions described in this document (FGCP, VRRP, and standalone session synchronization).
An introduction to the FGCP introduces the FGCP clustering protocol and many of its features and terminology.
FGCP configuration examples and troubleshooting describes configuring HA clusters and contains HA clustering configuration examples.
Virtual clusters describes configuring HA virtual clusters and contains virtual clustering configuration examples.
Full mesh HA describes configuring FortiGate Full mesh HA and contains a full mesh HA configuration example.
Operating clusters and virtual clusters describes how to operate a cluster and includes detailed information about how various FortiGate systems operate differently in a cluster.
HA and failover protection describes in detail how FortiGate HA device failover, link failover, and session failover work.
HA and load balancing describes how FGCP HA active-active load balancing works and how to configure it.
HA with FortiGate-VM and third-party products describes how FortiGates interact with third-party products.
VRRP describes FortiOS support of the Virtual Router Redundancy Protocol (VRRP) and its use for high availability.
FortiGate Session Life Support Protocol (FGSP) describes how to use the FGSP feature to support using external routers or load balancers to distribute or load balance sessions between two peer FortiGates.