This counts CCMs received whose sequence number did not follow the expected order from the sending MEP, a gap or duplicate in the numbering each CCM carries so the receiver can detect lost or reordered heartbeats. A rising count here, even while overall CCM reception looks continuous, is an early indicator of intermittent packet loss or reordering on the path to a specific remote MEP, the kind of subtle issue that would not otherwise trip a hard connectivity alarm. Seeing this counter tick up by exactly one every few minutes on an otherwise up service is consistent with occasional microbursts dropping a CCM here and there rather than a full outage.