Chapter 14 Configuring Failover; Failover System Requirements; Software Requirements; License Requirements - Cisco 7604 Configuration Manual

Understanding Failover

Failover System Requirements

This section describes the software and license requirements for FWSMs in a failover configuration.
This section includes the following topics:
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Software Requirements

The two units in a failover configuration must have the same major (first number) and minor (second
number) software version. However, you can use different versions of the software during an upgrade
process; for example, you can upgrade one unit from Version 3.1(1) to Version 3.1(2) and have failover
remain active. We recommend upgrading both units to the same version to ensure long-term
compatibility.

License Requirements

Both units must have the same license. In the occurrence of a license mismatch, a failover pair enters
pseudo-standby mode, a condition in which failover is disabled. FWSMs in an active/active
configuration return to the active/standby state and do not pass any traffic.

Failover and State Links

This section describes the failover and the state links, which are dedicated connections between the two
units in a failover configuration. This section includes the following topics:
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Failover Link

The two units in a failover pair constantly communicate over a failover link to determine the operating
status of each unit. The following information is communicated over the failover link:
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Caution All information sent over the failover and Stateful Failover links is sent in clear text unless you secure
the communication with a failover key.
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
14-2
Software Requirements, page 14-2
License Requirements, page 14-2
Failover Link, page 14-2
State Link, page 14-3
The unit state (active or standby).
Hello messages (keep-alives).
Network link status.
MAC address exchange.
Configuration replication and synchronization.
Chapter 14 Configuring Failover
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