This read-only Counter64 counts IGMP packets dropped because the switch ran out of internal resources to process them. This is the counter that shows real control-plane overload — sustained increases mean the incoming IGMP message rate on this instance is outrunning the snooping/proxy engine's capacity, the first symptom of an IGMP flood; because it is drawn from this table's currently-accumulating, short-interval bin, it reflects only the last few minutes of activity, so it's the value to watch for a fast-forming problem rather than a long-term trend. On an access port serving a multi-dwelling unit, a count of 1,134 over the last 15 minutes 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.