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Cisco ASA Series CLI Configuration Guide
Chapter 1 Information About Failover
Failover and Stateful Failover Links
Failover and Stateful Failover Links
This section describes the failover and the Stateful Failover links, which are dedicated connections
between the two units in a failover configuration. This section includes the following topics:
•
•
Stateful Failover Link, page 1-4
•
Avoiding Interrupted Failover Links, page 1-5
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:
•
The unit state (active or standby)
•
Hello messages (keep-alives)
•
Network link status
•
MAC address exchange
•
Configuration replication and synchronization
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. If the ASA is used to terminate VPN tunnels, this information
includes any usernames, passwords and preshared keys used for establishing the tunnels. Transmitting
this sensitive data in clear text could pose a significant security risk. We recommend securing the failover
communication with a failover key if you are using the ASA to terminate VPN tunnels.
You can use any unused interface on the device as the failover link; however, you cannot specify an
interface that is currently configured with a name. The failover link interface is not configured as a
normal networking interface; it exists for failover communication only. This interface should only be
used for the failover link (and optionally for the Stateful Failover link).
Connect the failover link in one of the following two ways:
•
Using a switch, with no other device on the same network segment (broadcast domain or VLAN) as
the failover interfaces of the ASA.
•
Using a crossover Ethernet cable to connect the appliances directly, without the need for an external
switch.
Note
When you use a crossover cable for the failover link, if the interface fails, the link is brought down on
both peers. This condition may hamper troubleshooting efforts because you cannot easily determine
which interface failed and caused the link to come down.
Note
The ASA supports Auto-MDI/MDIX on its copper Ethernet ports, so you can either use a crossover cable
or a straight-through cable. If you use a straight-through cable, the interface automatically detects the
cable and swaps one of the transmit/receive pairs to MDIX.
Summary of Contents for 5505 - ASA Firewall Edition Bundle
Page 28: ...Glossary GL 24 Cisco ASA Series CLI Configuration Guide ...
Page 61: ...P A R T 1 Getting Started with the ASA ...
Page 62: ......
Page 219: ...P A R T 2 Configuring High Availability and Scalability ...
Page 220: ......
Page 403: ...P A R T 2 Configuring Interfaces ...
Page 404: ......
Page 499: ...P A R T 2 Configuring Basic Settings ...
Page 500: ......
Page 533: ...P A R T 2 Configuring Objects and Access Lists ...
Page 534: ......
Page 601: ...P A R T 2 Configuring IP Routing ...
Page 602: ......
Page 745: ...P A R T 2 Configuring Network Address Translation ...
Page 746: ......
Page 845: ...P A R T 2 Configuring AAA Servers and the Local Database ...
Page 846: ......
Page 981: ...P A R T 2 Configuring Access Control ...
Page 982: ......
Page 1061: ...P A R T 2 Configuring Service Policies Using the Modular Policy Framework ...
Page 1062: ......
Page 1093: ...P A R T 2 Configuring Application Inspection ...
Page 1094: ......
Page 1191: ...P A R T 2 Configuring Unified Communications ...
Page 1192: ......
Page 1333: ...P A R T 2 Configuring Connection Settings and QoS ...
Page 1334: ......
Page 1379: ...P A R T 2 Configuring Advanced Network Protection ...
Page 1380: ......
Page 1475: ...P A R T 2 Configuring Modules ...
Page 1476: ......
Page 1549: ...P A R T 2 Configuring VPN ...
Page 1550: ......
Page 1965: ...P A R T 2 Configuring Logging SNMP and Smart Call Home ...
Page 1966: ......
Page 2059: ...P A R T 2 System Administration ...
Page 2060: ......
Page 2098: ...1 8 Cisco ASA Series CLI Configuration Guide Chapter 1 Troubleshooting Viewing the Coredump ...
Page 2099: ...P A R T 2 Reference ...
Page 2100: ......