The value of vRtrPimNgIfGrpSrcJoinPruneTimer indicates the time
remaining before the router transitions the value of
vRtrPimNgIfGrpSrcJPState to 'noInfo'.
The timer is started or restarted when a valid Join message is
received. If the value of this object is zero and
vRtrPimNgIfGrpSrcJPState is 'join' state, it means that the
downstream router sent a holdtime of '0xffff'. In this case,
vRtrPimNgIfGrpSrcJPState will not transition until an appropriate
cancelling of Join or Prune message is received.