Cisco ASA Series Cli Configuration Manual page 337

Information About Failover
This chapter provides an overview of the failover features that enable you to achieve high availability on
the Cisco 5500 series ASAs. For information about configuring high availability, see
"Configuring Active/Active Failover"
This chapter includes the following sections:
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Introduction to Failover and High Availability
Configuring high availability requires two identical ASAs connected to each other through a dedicated
failover link and, optionally, a Stateful Failover 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.
The ASA 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 also lets you configure traffic
sharing 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.
Introduction to Failover and High Availability, page 1-1
Failover System Requirements, page 1-2
Failover and Stateful Failover Links, page 1-3
Active/Active and Active/Standby Failover, page 1-8
Stateless (Regular) and Stateful Failover, page 1-9
Intra- and Inter-Chassis Module Placement for the ASA Services Module, page 1-11
Transparent Firewall Mode Requirements, page 1-15
Auto Update Server Support in Failover Configurations, page 1-16
Failover Health Monitoring, page 1-18
Failover Times, page 1-20
Failover Messages, page 1-20
C H A P T E R
or Chapter 1, "Configuring Active/Standby Failover."
Cisco ASA Series CLI Configuration Guide
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Chapter 1,
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