The value of tmnxVrrpPortDownEventPriority specifies the
priority level associated with this event. When the operational
state of the event transitions to one of the 'set' states,
this value will either be subtracted from the in-use priority
(if the event is a 'delta' event) or the in-use priority
will be explicitly overridden by this priority value
(if the event is an 'explicit' event).