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New Member

reset interface stats


I have two individual port channels made up of two ISL's over DWDM links. I have had some (still to be identified) problems with the links and there are a lot of errors on one port. How do I reset the interface stats? Looking at an error number in the 10000's doesn't do much for me. A change in the single digits would be better as I think I might have discovered the problems. Telling the interface to ignore bit errors also has made my life easier.


Cisco Employee

Re: reset interface stats

If you are looking to clear the interface counters via the command line, this command will work.

clear counters interface fc x/y

If you are referring to the asic counters, then that's a bit different.

For example module 2 asics.

attach module 2

clear asic-cnt all


I would not recommend doing the all asic count clearing process on a heavily utilized line card.

Hope this helps,


New Member

Re: reset interface stats

Hi Mike,

Thanks for the info. I cleared the interface fc counters and also the port-channel counters hoping it would clear the Errors and Discards seen in the switch Device Manager Summary GUI. It didn't. Any ideas on how to do that?

Also, while looking at the syslog output, I noticed some link failures and then:

%PORT-5-IF_DOWN_LOOPBACK_ISOLATION %$VSAN XX%$ Interface fcx/x is down (Isolation due to port loopback to same switch).

What does that mean? The system at the other end is having problems.

Thanks again for the wonderful assistance.


New Member

Re: reset interface stats

Will the module reboot or cause corruption?

Like Stephen, I've tried clearing the counters without any success so I'm interested in how to do this too.


New Member

Re: reset interface stats


I've run into this about 2 years ago when connecting ISL's between 2 Cisco 9509's going over DWDM. For about 2 weeks thought it was Qwest (teleco) or our Nortel gear that our light was going through at the MPOP (sp?). Turned out our new Cisco 9509 switch at our DR site had a clock failure that was only diagnosed when a local Cisco engineer came in with a Finisar to see what was going on.

During the troubleshooting stage and before we knew we had a clock failure, I put a hard loopback on the fiber just before our Cisco 9509 at our DR site pointing towards our production site. This validated the Qwest network and Nortel gear was good and the port on our Cisco 9509 at our production site went into a "loopback isolation". It does this when the switch is seeing his own signal.

I hope this helps.