A read-create Unsigned32 setting the maximum number of multicast groups a specific port is allowed to join simultaneously, bounded by hh3cMPortGroupLimitMinNumber and hh3cMPortGroupLimitMaxNumber. This caps per-port multicast fan-out to prevent a single port, or a misbehaving device on it, from consuming excessive multicast bandwidth or hardware table space by joining too many groups. An admin limiting a residential access port to a small number of simultaneous IPTV channels might set this to 4.