This counts instances where a PDU's source and destination addresses both resolved to the same physical port, an unusual and typically disallowed condition since SMDS traffic is meant to traverse the switch fabric to a different destination port. An admin treats a nonzero count as a sign of a misconfiguration, such as a customer's own address mistakenly appearing in their own destination screen list, or a loop in how addresses were provisioned. For example, if a customer's router accidentally sent a test PDU addressed to its own SMDS address, that self-addressed traffic would register here rather than being forwarded normally.