1-5
Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring Active/Active Failover
Information About Active/Active Failover
• The unit has a power failure.
• The unit has a software failure.
• You force a failover. (See Forcing Failover, page 1-24.)
Failover is triggered at the failover group level when one of the following events occurs:
• Too many monitored interfaces in the group fail.
• You force a failover. (See Forcing Failover, page 1-24.)
You configure the failover threshold for each failover group by specifying the number or percentage of
interfaces within the failover group that must fail before the group fails. Because a failover group can
contain multiple contexts, and each context can contain multiple interfaces, it is possible for all
interfaces in a single context to fail without causing the associated failover group to fail.
See the “Failover Health Monitoring” section on page 1-18 for more information about interface and unit
monitoring.
Failover Actions
In an Active/Active failover configuration, failover occurs on a failover group basis, not a system basis.
For example, if you designate both failover groups as active on the primary unit, and failover group 1
fails, then failover group 2 remains active on the primary unit while failover group 1 becomes active on
the secondary unit.
Note When configuring Active/Active failover, make sure that the combined traffic for both units is within the
capacity of each unit.
Table 1-2 shows the failover action for each failure event. For each failure event, the policy (whether or
not failover occurs), actions for the active failover group, and actions for the standby failover group are
given.
Table 1-2 Failover Behavior for Active/Active Failover
Failure Event Policy
Active Group
Action
Standby
Group Action Notes
A unit experiences a power or
software failure
Failover Become standby
Mark as failed
Become active
Mark active as
failed
When a unit in a failover pair fails,
any active failover groups on that
unit are marked as failed and
become active on the peer unit.
Interface failure on active failover
group above threshold
Failover Mark active
group as failed
Become active None.
Interface failure on standby failover
group above threshold
No failover No action Mark standby
group as failed
When the standby failover group is
marked as failed, the active failover
group does not attempt to fail over,
even if the interface failure
threshold is surpassed.
Formerly active failover group
recovers
No failover No action No action Unless failover group preemption is
configured, the failover groups
remain active on their current unit.
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