This read-only Counter64 counts IGMP packets received with an invalid IP checksum. Checksum failures point to link-layer corruption or a failing NIC/cable upstream of this port rather than a protocol issue, so admins treat a rising count here as a physical-layer lead; 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 residential VLAN used for multicast video delivery, a count of 616 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.