Cisco ASA 5505 Configuration Manual page 1224

Configuring Active/Standby Failover
IPv6 Guidelines
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Model Guidelines
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Additional Guidelines and Limitations
The following guidelines and limitations apply for Active/Standby failover:
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Configuring Active/Standby Failover
This section describes how to configure Active/Standby failover.
This section includes the following topics:
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Configuring Failover
Follow these steps to configure Active/Standby failover on both units.
The speed and duplex settings for the failover interface cannot be changed when Failover is enabled. To
change these settings for the failover interface, you must configure them in the Configuration >
Interfaces pane before enabling failover.
Step 1 Open the Configuration > Device Management > Failover > Setup tab.
Step 2 Check the Enable Failover checkbox.
Note
Cisco ASA 5500 Series Configuration Guide using ASDM
59-6
IPv6 failover is supported.
Stateful failover is not supported on the Cisco ASA 5505 adaptive security appliance.
To receive packets from both units in a failover pair, standby IP addresses need to be configured on
all interfaces.
The standby IP addresses are used on the security appliance that is currently the standby unit, and
they must be in the same subnet as the active IP address on the corresponding interface on the active
unit.
If you change the console terminal pager settings on the active unit in a failover pair, the active
console terminal pager settings change, but the standby unit settings do not. A default configuration
issued on the active unit does affect behavior on the standby unit.
When you enable interface monitoring, you can monitor up to 250 interfaces on a unit.
By default, the security appliance does not replicate HTTP session information when Stateful
Failover is enabled. Because HTTP sessions are typically short-lived, and because HTTP clients
typically retry failed connection attempts, not replicating HTTP sessions increases system
performance without causing serious data or connection loss. The failover replication http command
enables the stateful replication of HTTP sessions in a Stateful Failover environment, but it could
have a negative impact upon system performance.
Configuring Failover, page 59-6
Configuring Optional Active/Standby Failover Settings, page 59-9
Failover is not actually enabled until you apply your changes to the device.
Chapter 59 Configuring Active/Standby Failover
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