This Counter64 tallies the total number of bytes the CNT device has transmitted outbound over this transport-layer link since the counter was last reset. Because it only counts what leaves the link, a monitoring admin can compare successive polls to derive real outbound throughput and confirm the transport connection is actively passing data rather than stalled. For example, if the counter stops incrementing across several polling intervals on an otherwise 'up' transport, that flags a hung connection worth investigating.