Understanding Failover - Cisco 7604 Configuration Manual

Configuring Failover
This chapter describes the FWSM failover feature, which lets you configure two FWSMs so that one will
take over operation if the other one fails. Failover is compatible with both routed and transparent firewall
modes, and with single and multiple context modes.
This chapter includes the following sections:
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For sample failover configurations, see the

Understanding Failover

The failover configuration requires two identical FWSMs connected to each other through a dedicated
failover link and, optionally, a state link. The health of the active interfaces and units is monitored to
determine if specific failover conditions are met. If those conditions are met, failover occurs.
FWSM supports two failover configurations, Active/Active failover and Active/Standby failover. Each
failover configuration has its own method for determining and performing failover.
With Active/Active failover, both units can pass network traffic. This lets you configure load balancing
on your network. Active/Active failover is available only on units running in multiple context mode.
With Active/Standby failover, only one unit passes traffic while the other unit waits in a standby state.
Active/Standby failover is available on units running in either single or multiple context mode.
Both failover configurations support stateful or stateless (regular) failover.
This section includes the following topics:
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Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
OL-20748-01
Understanding Failover, page 14-1
Configuring Failover, page 14-20
Controlling and Monitoring Failover, page 14-40
Failover System Requirements, page 14-2
Failover and State Links, page 14-2
Intra- and Inter-Chassis Module Placement, page 14-3
Transparent Firewall Requirements, page 14-7
Active/Standby and Active/Active Failover, page 14-8
Regular and Stateful Failover, page 14-17
Failover Health Monitoring, page 14-19
C H A P T E R
"Failover Example Configurations" section on page
14
B-18.
14-1