A read-create setting, defaulting to disabled, controlling what happens on a port when its IGMP group count is already at the configured hh3cMPortGroupLimitNumber and a new group join request arrives: if enabled, the existing group with the lowest multicast address is replaced by the new one; if disabled, the new group request is simply refused. This gives an admin control over multicast join behavior at capacity, choosing between rejecting new channel requests outright or automatically evicting the lowest-address group to make room. An admin who wants channel-surfing subscribers to always be able to join a new channel, even at the cap, would enable this so the lowest-address group gets bumped automatically.