CRC errors

[miket]

In troubleshooting connectivity on a switch port, a 'show int' command shows that the port is getting CRC errors. What exactly is a CRC error and what causes them?

[Prashanth Krishnappa]

CRC is Cyclic Redundancy Check. Most of our switches use the store-and-forward switching method and so the switch copies the entire frame into its onboard buffers and computes the cyclic redundancy check (CRC). The frame is discarded if it contains a CRC error or if it is a runt (less than 64 bytes, including the CRC) or a giant (more than 1518 bytes, including the CRC). If the frame is discarded, the counter is incremented. Check for any duplex mismatch, bad cable/NIC. Also the following page should be useful

http://www.cisco.com/warp/public/473/53.shtml

[n.ahmedkhan]

For this CRC errors .. u can try replacing u r server network cards... actually there r situations where faulty network cards created this kind of errors....

sol: check the port which gives crc errors and change the NIC card for those systems and then monitor...

[n.ahmedkhan]

sorry i forgot to mention onething....

first u try to upgrade the code of the NIC cards if it is available r else try to reload the drivers again for that servers .. else in the worst if still rpob persists try to change the cards....

[dhayes]

CRC errors are generally caused by either bad cable or duplex mismatch. You can copy the "show int" output to CIsco's tool, and it will give you an explaination