Exactly as described, this is a running total of transmitted packets on this benchmark port that had CRC errors. CRC errors on transmit specifically, rather than receive, most often point to a problem inside the sending device itself -- a bad internal signal path or PHY issue on this test port -- rather than the far-end link or cabling, since the frame was already corrupted before it left the box. For example, this counter climbing steadily during an otherwise healthy-looking test would prompt swapping the SFP or line card on this specific port rather than troubleshooting the remote reflector.