NOTE: The alert detailed below is given with a Check Point ClusterXL example, although F5 BIG-IP LTM is covered for this issue as well (see SOL7332).
This is a real life sample alert from indeni
A fail over was identified at Device time: Jul 18 03:02 2014 UTC, indeni time: Jul 18 03:02 2014 UTC. This device is now the active member of the cluster and in the period immediately following the fail over (3 minutes more or less) it received 0 packets compared to 104462 packets that were received by jcnj-fw2 (10.10.10.2) in a similar amount of time immediately BEFORE the fail over. This indicates the possibility that the surrounding network equipment may not be aware of the fail over on the layer 2 level.
Manual Remediation Steps:
It is possible this is caused by the fact that during a fail over the responsibility for the virtual IPs moves from one cluster member to the other and the MAC addresses change. ClusterXL issues gratuitous arps to deal with this but it may not work with your equipment. Please review SK50840 for more information.
How does this alert work?
indeni monitors the traffic passing through all members of an HA cluster. If it sees that post a failover the newly active member isn’t seeing remotely similar levels of traffic as the pre-failover active member did, the alert is triggered.