This counts frames transmitted from this interface that were marked as CRC errors on the way out. Unlike the receive-side CRC counter, a CRC error on this port's transmit path can't be blamed on external noise on the wire since the frame hadn't left the switch yet -- a rise here during the current, still-accumulating short interval bin points at an internal ASIC, backplane, or line-card fault on this specific interface rather than at cabling. For example, TxCrcErrorPkts incrementing on this in-progress short-interval bin for a port with a clean RxCrcErrorPkts history would justify swapping the line card feeding that port before suspecting the cable plant.