In the event of a failover in an HA pair, and a device transitions from a non-active state to active state, the following happens:
A request is made to enable all layer 3 physical links.
Two gratuitous ARPs (GARPs) are immediately sent.
Eight GARPs are scheduled to be sent in 1 second intervals.
Note: The links may take up to 4 seconds to become active, so it's possible that not all GARPs reach the wire. This not supported on L3 sub-interfaces.