This feature is disabled by default, which is indicated
by a timer value of 0 seconds. When IGMP is enabled and
the value of the Delayed Group Flush Timer is not zero,
traffic filters for any previously-joined IGMP groups
which no longer have active members will persist for
the number of seconds indicated by the timer. This has
the effect of dropping any additional unjoined traffic
for an empty group until the Delayed Group Flush Timer
expires, at which time the traffic filter is then
removed.