This counter records the total number of IGMP packets received by the endstation, i.e., multicast group membership join/leave messages. Since IGMP is what tells the router which multicast groups downstream devices actually want to receive, a stuck-at-zero value here despite an expected multicast feed means no device has ever signaled a group join, which is the first thing to check before assuming a satellite-side multicast delivery fault. When a new set-top box on the LAN subscribes to a multicast video channel, an admin would expect this counter to tick upward by a handful of packets even before any of the actual multicast payload counter moves.