This read-only Counter64 counts messages the host-side logic discarded when a join or leave arrived on a port that has no established router port to forward toward. A climbing count on an access port means subscribers are trying to join multicast groups but the switch has no upstream path configured yet — a deployment gap rather than a subscriber fault; because it is drawn from the most recently completed 24-hour bin, frozen once the day rolled over, it is frozen and safe to use for day-over-day comparison, since no further traffic will ever be added to it. On a metro aggregation uplink carrying several video EVCs, a count of 122 over the last completed collection window is the kind of number an admin would trend against the join/leave rate on the same port to judge whether it's normal channel-surfing or an anomaly worth a closer look.