A failure of the interconnection between the two locations is detected by both nodes, and each node takes over the IP addresses of the partner. Signaling traffic is still routed to both nodes as before. Both nodes attempting to take over each other’s function has to be avoided, so one of the nodes will be shut down.
After Shutdown of one of the nodes, the WAN continues to send signaling traffic to the now deactivated node, which cannot be sent to the partner node because the layer-2 bridge is down. Manual intervention is needed to reroute the traffic to location 2.
To avoid both nodes attempting to set up and clear calls to the same SIP phone simultaneously, both nodes send an SNMP power-down command to the remote access card of the partner node. This is controlled by different timers, so one node powers down its partner before the partner can send its own power-down command.
Parent topic: Cluster Redundancy