3850 switch

[tstrode01]

I have a strange issue that I am having trouble finding a solution.

One building on our campus loses connectivity every few months.  When I troubleshoot the 3850 for that location, I notice an exponential increase in crc errors on the link back to the core switch.  The core side does not see the errors.  I swap out fiber patch cables at both ends, as well as SFPs.  The only thing that resolves the issue until the next time it arises is switching fiber pairs.  We have had all twelves of fiber recertified and does not register any issues.

Has anyone experienced this or have a solution?

[chrihussey]

Got some questions:

1- What needs to be done to restore connectivity?

2- What type of SFPs are you using, what type of fiber is it and what's the distance?

3- Can you post a "show inventory" and  "show version"?

Thanks

[nazimkha]

Check the transmit and receive power of the port, maybe there is fiber burnout. The switch port might have also gone bad

[jbogdan]

What type of fiber?  SM or MM?  what is the distance between sites?

[Leo Laohoo]

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@tstrode01 wrote:

 I notice an exponential increase in crc errors on the link back to the core switch.  The core side does not see the errors. 

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So only the remote end is experiencing the CRC errors?  

The next time this happens, post the complete output to the command "sh interface <PORT> controll".