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 the most recently completed short-interval historical bin, it is a closed record of the interval right before the current one, useful for checking whether a problem seen right now had already started in the previous window. On a residential VLAN used for multicast video delivery, a count of 382 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.