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.

Configuring and connecting HA clusters 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 a cluster 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 in detail how FortiGate HA active-active load balancing load balances sessions.

HA with FortiGate-VM and third-party products describes how FortiGate units 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 the FortiGate standalone session synchronization feature and its use for high availability.

Configuring FRUP describes how to set up a FortiGate Redundant UTM Protocol (FRUP) cluster consisting of two FortiGate-100D units.