UDLD on GigabitEthernet link

Posted on 2009-12-18
Last Modified: 2012-05-08

I have a Distribution layer switch connected to an access layer switch through GigabitEthernet link. This link went down and I am seeing the following message on the access  layer switch:

Dec 17 22:41:51.073 est: %PM-4-ERR_DISABLE: udld error detected on Gi0/1, putting Gi0/1 in err-disable state
Dec 17 22:41:52.073 est: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to down
Dec 17 22:41:53.085 est: %LINK-3-UPDOWN: Interface GigabitEthernet0/1, changed state to down

Please let me know how to fix this?

Thanks in advance.
Question by:thunder8080
    LVL 34

    Accepted Solution


    it seem there is a proble with the patch cable or the gigabit port, please change the patch cable, and tell us the result!

    Best regards,
    LVL 17

    Assisted Solution


    Since UDLD checks that the link is bidirectional, you need to check the gigabit ports at both ends of the link. Also check that there aren't any cabling misconfigurations.
    LVL 50

    Expert Comment

    by:Don Johnston
    If the "link went down" after it had been working, I would first reseat any loose connectors. If that doesn't clear it up, it's probably a bad cable or connector.

    If the link has never worked then it's either a misconfiguration or a bad cable/connector.

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