IKE Message ID Sync is supported in FortiOS 5.2. Message ID Sync allows IKEv2 to re-negotiate send and receive message ID counters after a high availability fail over. By doing this, the established IKE SA can remain up, instead of re-initializing.

A diagnose command has also been added to show statistics for the number of HA messages sent/received for IKE: diagnose vpn ike ha stats.