Failover

The failover functionality is particularly favored for systems like database servers, where consistent operation and high availability are essential. Additionally, firewall systems—critical to ensuring internal network security—usually incorporate an HA cluster design with failover capabilities, commonly known as "stateful failover." Stateful failover specifically refers to the capability of transferring the active firewall's current session information directly to its standby firewall. If the active firewall encounters an issue, this ensures uninterrupted security by handing over processing seamlessly to the standby unit. To achieve stateful failover, two redundant firewalls must be interconnected using failover cables.

The F5 BIG-IP platform provided by F5 also supports this stateful failover functionality. Failover cables can be either dedicated serial cables or standard LAN cables. When serial cables are used for failover, the configuration is referred to as "Serial Failover," whereas failover through LAN cables is called "Network Failover."