Note that the term 'notification' here refers to an RF
notification and not an SNMP notification.
As the standby unit progresses to the 'standbyHot' state,
asynchronous messages are sent from the active unit to the
standby unit which must then be acknowledged by the standby
unit. If the active unit receives the acknowledgement during
the time period specified by this object, progression proceeds
as normal. If the timer expires and an acknowledgement was not
received by the active unit, a switch of activity occurs.