What Causes a Failover Event?
In a Security Appliance failover configuration, one of the Security Appliances is considered
the active unit, and the other is the standby unit. As their names imply, the active unit
performs normal network functions and the standby unit monitors and is ready to take
control should the active unit fail to perform its functionality. A failover event occurs after a
series of tests determines that the primary (active) unit can no longer continue providing its
services, at which time the standby Security Appliance assumes the role of the primary. The
main causes of failover are shown in Table 12-2.
NOTE If multiple contexts are enabled on a Security Appliance, the Security Appliance
can act as a standby unit for another Security Appliance while acting as an active unit for
traffic flowing through it.