两台ASA5520配置Failover，简单拓扑如下：

ASA5520-1：

ciscoasa> en
Password:
ciscoasa# conf t
ciscoasa(config)# hostname ASA5520
ASA5520(config)# int g0/0
ASA5520(config-if)# nameif outside
INFO: Security level for "outside" set to 0 by default.
ASA5520(config-if)# no shut
ASA5520(config-if)# ip add 100.1.1.1 255.255.255.0
ASA5520(config-if)# int g0/1
ASA5520(config-if)# nameif inside
INFO: Security level for "inside" set to 100 by default.
ASA5520(config-if)# no shut
ASA5520(config-if)# ip add 192.168.0.1 255.255.255.0
ASA5520(config-if)# interface Management0/0
ASA5520(config-if)# no shut
ASA5520(config-if)# exit
ASA5520(config)# failover lan unit primary
ASA5520(config)# failover lan interface failover Management0/0
INFO: Non-failover interface config is cleared on Management0/0 and its sub-interfaces
ASA5520(config)# failover interface ip failover 1.1.1.1 255.255.255.0 standby 1.1.1.2
ASA5520(config)# failover
ASA5520(config)# write memory
Building configuration...
Cryptochecksum: b6bb8357 a400eae0 d063037d 1ef88a95

1893 bytes copied in 3.520 secs (631 bytes/sec)
[OK]
ASA5520(config)#

ASA5520-2：

ciscoasa> en
Password:
ciscoasa# conf t
ciscoasa(config)# interface Management0/0
ciscoasa(config-if)# no shut
ciscoasa(config-if)# exit
ciscoasa(config)# failover lan unit secondary
ciscoasa(config)# failover lan interface failover Management0/0
INFO: Non-failover interface config is cleared on Management0/0 and its sub-interfaces
ciscoasa(config)# failover interface ip failover 1.1.1.1 255.255.255.0 standby 1.1.1.2
ciscoasa(config)# failover
ciscoasa(config)# .

Detected an Active mate
Beginning configuration replication from mate.
ASA5520(config)# End configuration replication from mate.
ASA5520(config)#
ASA5520(config)# show failover
Failover On
Failover unit Secondary
Failover LAN Interface: failover Management0/0 (up)
Unit Poll frequency 1 seconds, holdtime 15 seconds
Interface Poll frequency 15 seconds
Interface Policy 1
Monitored Interfaces 2 of 250 maximum
Version: Ours 7.0(8), Mate 7.0(8)
Last Failover at: 09:22:55 UTC Sep 7 2009
This host: Secondary - Standby Ready
Active time: 0 (sec)
slot 0: ASA5520 hw/sw rev (2.0/7.0(8)) status (Up Sys)
slot 1: empty
Interface outside (0.0.0.0): Normal (Waiting)
Interface inside (0.0.0.0): Normal (Waiting)
Other host: Primary - Active
Active time: 1477 (sec)
slot 0: ASA5520 hw/sw rev (2.0/7.0(8)) status (Up Sys)
slot 1: empty
Interface outside (100.1.1.1): Normal (Waiting)
Interface inside (192.168.0.1): Normal (Waiting)

Stateful Failover Logical Update Statistics
Link : Unconfigured.

ASA5520(config)#

当关闭ASA5520-1时，show failover：

ASA5520(config)# sh fa
Failover On
Failover unit Secondary
Failover LAN Interface: failover Management0/0 (Failed - No Switchover)
Unit Poll frequency 1 seconds, holdtime 15 seconds
Interface Poll frequency 15 seconds
Interface Policy 1
Monitored Interfaces 2 of 250 maximum
Version: Ours 7.0(8), Mate 7.0(8)
Last Failover at: 10:00:56 UTC Sep 7 2009
This host: Secondary - Active
Active time: 7 (sec)
slot 0: ASA5520 hw/sw rev (2.0/7.0(8)) status (Up Sys)
slot 1: empty
Interface outside (100.1.1.1): No Link (Waiting)
Interface inside (192.168.0.1): No Link (Waiting)
Other host: Primary - Failed
Active time: 1726 (sec)
slot 0: ASA5520 hw/sw rev (2.0/7.0(8)) status (Up Sys)
slot 1: empty
Interface outside (0.0.0.0): Unknown (Waiting)
Interface inside (0.0.0.0): Unknown (Waiting)

Stateful Failover Logical Update Statistics
Link : Unconfigured.

ASA5520(config)#