The value inserted into the Holdtime field of a PIM
Join/Prune message sent on this interface. A value of 65535
represents an 'infinite' holdtime. Implementations are
recommended to use a holdtime that is 3.5 times the value of
hwPimInterfaceJoinPruneInterval, or 65535 if
hwPimInterfaceJoinPruneInterval is set to zero. PIM-DM
implementations are recommended to use the value of
hwPimInterfacePruneLimitInterval.