High availability (HA) refers to the ability of a system to have a lower chance of failing during normal operation. Many Fortinet products include HA features that most commonly allow two or more devices to appear to function as one. In these redundant configurations, often called clusters, the devices in the cluster share information about their activities so that if one of the devices in the cluster fails, the other device can automatically take over full operation with only a minor interruption.
Fortinet products employ a wide variety of technologies to achieve HA and some of these HA technologies allow Fortinet products to join a cluster with third party products. FortiOS and FortiGates support the following HA technologies:
- The FortiGate Clustering Protocol (FGCP) is a proprietary HA technology in which two or more FortiGate units operate as a cluster.
- The FortiGate Session Life Support Protocol (FGSP) is similar to the FGCP, but relies on external routers or load balancers.
- Virtual Router Redundancy Protocol (VRRP) is an industry standard protocol that can be used for HA between FortiGates or between FortiGates and 3rd party routers that also support VRRP.
- Session-Aware Load Balancing Clustering (SLBC) combines FortiController-5000 series load balancers with clusters of FortiGate-5000 workers. A variation of SLBC is also used by FortiGate-7000 products.
- Enhanced Load Balancing Clustering (ELBC) combines FortiSwitch-5000 series load balancers with clusters of FortiGate-5000 workers.
- Content clustering uses FortiSwitch-5203Bs or FortiController-5902Ds to load balance content sessions to FortiGate-5000 workers.