The CRC error packets are usually caused by interference of network cables. If the error packet count keeps increasing, check the cable quality first. It is normal if a few CRC error packets are received. This is often caused by poor contact of network cables. In this case, remove and reinstall the cables. Ensure that optical interfaces at both ends of a link work in the same auto-negotiation mode. If they work in non-auto-negotiation mode, ensure that the interfaces work at the same rate and in the same duplex mode.
It is recommended that idle fiber connectors be covered with dust-proof caps to keep the fiber connectors clean. An unclean fiber connector may degrade the quality of optical signals or even cause link failures or error codes on the link. In the command output in step 2, the Transfer Distance field indicates the transmission distance supported the optical module. View this field to determine whether the optical fiber length is within the allowed transmission distance range of the optical module.
For example, in the preceding command output, the transmission distance supported by the OM1 optical fiber is 30 m. If the actual transmission distance exceeds 30 m, use an optical fiber with a longer transmission distance. Multimode optical modules must be used with multimode optical fibers. What is the meaning of the CRC counter on a cisco device? Ask Question. Asked 8 years, 5 months ago. Active 5 years, 7 months ago. Viewed 55k times. If the CRC counter of an interface is high, normally it's a bad sign, but why?
If the count is high, what does this mean technically? What can cause this counter to go up? On which layer in the OSI model will this counter react? Improve this question. Bulki Bulki 2, 7 7 gold badges 23 23 silver badges 43 43 bronze badges.
Thats is perfect answer i was looking for. Most helpful — user Add a comment. Active Oldest Votes. The counter is increasing because your frames are being corrupted. Improve this answer. Peter 1, 10 10 silver badges 27 27 bronze badges. Great info ytti. Maybe add possible causes to your post like duplex mismatch and faulty cabling. Change cable then change ports at the switch end. I would say duplex mismatch. Once CRC in 33k is not acceptable.
I have ports with Terabytes of traffic and zero CRCs. Make sure that both sides of the link are either hard coded or auto [or at last restort a combo of both]. I did not mention duplex as he had no late collisions, if there are also late collisions, that screams duplex mismatch. It could be nothing more than noise on the cable. I have to say I worry more about errors than one error, but you still have an error rate of 0. Is this between equipment which is always on, or devices that might be being powered off?
Many errors are harmless if they occur at power off. You ought to get more fragments if you are powering off stuff at random, though. This is from equipment that is always on. Its goes from the wall to a switch that has a computer and a network printer.
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