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New Member

CRC Error

What is CRC Error? What is the cause of this error?

I've just installed GE link between two switches. I have found CRC error on that particular interface.

I have checked the FIber backbone, the result show a pass. I even change the fiber patch cord. The CRC error still exist.

What other possibility.

Thank you.

New Member

Re: CRC Error


What sort of distance are you talking?


Are the interface settings default at the moment?



Re: CRC Error

Every ethernet frame carries a FCS (Frame Check Sequence) field at the end of it and this field is filled with a CRC (Cyclic Redundancy Check)code computed using the entire ethernet frame (on the transmitting site). This CRC computation results with a 32-bit or 16-bit value and CRC is such a computation function that even if one-bit of the ethernet frame changes, result of the CRC computation changes. At the receiving side, CRC function is recomputed for the received ethernet frame and result is compared to the value found in the FCS field of the frame. If two results are different received frame is not the original one, i.e. corrupted.

So CRC check error may indicate any erroneus situation causing the frame to corrupt- faulty receiver/transmitter, faulty media, faulty or loose GBICs, loose connectors.


Re: CRC Error

Some CRC errors on ethernet are normal, the number depends on the distance and quality of the link (and the amount of traffic). CRCs occur when a frame becommes currupt in transit. How many CRCs are you getting (and how much traffic is on the link?) How long is the circuit and how many connectors are there between the 2 switches? I am assuming that the switches are relativly close together and that you have multimode cable between them. Make sure that all of your cable is multimode (probably orange, not yellow) and that your GBICs are SX, multimode. After you have checked that all of the connectors are tight, try jiggling the connectors, cables, etc and see if you get any errors. Also make sure the connectors are clean.

Also, try playing with the autonegotaiation option on the interface. Please reply with the number of CRCs and total packets on the link, and also what the distance between the switches is.....



New Member

Re: CRC Error

Thank you very much for the information.

The number of CRCs increasing very fast.

I've clean the fiber connectors, and finally all the CRCs gone. The infrastructure is old. So I manage to reduce the CRCs. Thanks again for your help guys..


Re: CRC Error

The next time you're down for maintenance, clean the panel-side of the connection too. Everybody cleans the connectors, noone ever cleans the panel connector (less necessary if you keep the caps on when they're not used).

There are some special small "q tips" (foam tipped applicators)just for getting into the receptacle.