About Host, Interface, and General Service Settings : About failover
  
About failover
In case of power loss or failure, appliances enter bypass mode to prevent network disruption. To maintain acceleration, you can set up redundant appliances as failover pairs.
For physical in-path failover, you configure two appliances: a primary and a backup. The primary is active, handling traffic, while the backup stays passive, checking the primary’s status. If the primary fails or hits its connection limit, the backup takes over. When the primary recovers, it notifies the backup, which stops handling new connections but continues processing existing ones until they finish.
In an out-of-path failover deployment, you deploy two server-side appliances and add a fixed-target rule to the client-side appliance defining primary and backup target appliances. When both the primary and backup appliances are functioning properly, the connections traverse the primary appliance. If the primary appliance fails, connections traverse the backup.
In an out-of-path failover setup, you deploy two server-side appliances and set a fixed-target rule on the client-side appliance to define the primary and backup. Normally, traffic goes through the primary appliance. If it fails, traffic shifts to the backup. The primary uses an out-of-band (OOB) connection to share internal data, and if it fails, the client-side appliance will switch to the backup after 40 to 45 seconds. During this time, new connections are passed through unoptimized. Every 30 seconds, the client-side appliance tries to reconnect to the primary. If both appliances are unreachable, new connections pass through unoptimized.
About general service settings
Failover support
About primary and backup failover pairs