Active/Standby Failover

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In active/standby implementations, only the primary device in a pair passes traffic. The standby device sits idle, ready to assume the active role should the primary device fail. The standby device may receive routing and state information from the primary device in order to facilitate stateful failover, but it doesn't actually pass traffic until the primary device fails.

The main differences between the two units in a failover pair are related to which unit is active and which unit is standby, namely which IP addresses to use and which unit is primary and actively passes traffic.

A few differences exist between the units based on which unit is primary (as specified in the configuration) and which unit is secondary:

• The primary unit always becomes the active unit if both units start up at the same time (and are of equal operational health).
• The primary unit MAC address is always coupled with the active IP addresses. The exception to this rule occurs when the secondary unit is active and cannot obtain the primary MAC address over the failover link. In this case, the secondary MAC address is used.

Configuration

(Note: First complete basic configuration as per given in the Topology Figure)

Topology

ASA_Active

int e0/0

nameif outside

ip add 101.1.1.100 255.255.255.0

no shut

exit

int e0/1

ip add 192.168.1.1 255.255.255.0

nameif inside

no shut

exit

inte0/2

no shut

ASA_Standby

inte0/2

no shut

ASA_Active

failover lan unit primary

failover lan interface fover e0/2

failover link fover e0/2

failover interface ip fover 10.0.0.100 255.255.255.0 standby 10.0.0.101

int e0/0

ip add 101.1.1.100 255.255.255.0 standby 101.1.1.101

exit

int e0/1

ip add 192.168.1.1 255.255.255.0 standby 192.168.1.2

failover replication http

failover

ASA_Standby

failover lan unit secondary

failover lan interface fover e0/2

failover link fover e0/2

failover interface ip fover 10.0.0.100 255.255.255.0 standby 10.0.0.101

failover replication http

failover

(Note: by default all the interfaces in monitor state by failover)

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