When a failover occurs
The following steps are followed after a device or link failure of the primary unit causes a failover.
1. If the primary unit fails, the subordinate unit negotiates to become the primary unit.
2. The new primary unit changes the MAC addresses of all of its interfaces to the HA virtual MAC addresses.
The new primary unit has the same IP addresses and MAC addresses as the failed primary unit.
3. The new primary units sends gratuitous ARP packets to the 10.10.101.0 network to associate its internal IP address with the internal virtual MAC address.
4. The new primary units sends gratuitous ARP packets to the 172.20.120.0 network to associate its external IP address with the external virtual MAC address.
5. Traffic sent to the cluster is now received and processed by the new primary unit.
If there were more than two cluster units in the original cluster, the new primary unit would load balance packets to the remaining cluster members.