The command "show interface fa0/1" prints the following output:

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What is the difference between "CRC" and "input errors"? CRC errors confirms that a frame error has occured, but what about "input errors"?

  • If you are getting CRC errors, there is a good chance that you have an issue with the cable. If you are just seeing Input errors, to fix my issue, it was a duplex and speed issue and i needed to set the interface to auto negotiate. The interface has been hard coded to speed 100 and duplex full. Jul 25, 2017 at 12:04

2 Answers 2


The "input errors" counter will increment whenever the interface receives a frame with any sort of input error, which includes CRC among other types of errors. Each frame is only counted once, no matter how many types of specific errors it contains.

You can see an example of this if you check this recent question which also has input errors.


See this page, table 4-6:


Description of input errors from that page:

Includes runts, giants, no buffer, CRC, frame, overrun, and ignored counts. Other input-related errors can also cause the input error count to be increased, and some datagrams may have more than one error; therefore, this sum may not balance with the sum of enumerated input error counts.

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