if (!memcmp(&mgid0, &group->rec.mgid, sizeof mgid0)) {
rb_erase(&group->node, &group->port->table);
mcast_insert(group->port, group, 1);
if (!memcmp(&mgid0, &group->rec.mgid, sizeof mgid0)) {
rb_erase(&group->node, &group->port->table);
mcast_insert(group->port, group, 1);