Cisco 1841 Fas 0/0 Interface UP porotocol Down

Unanswered Question
Jun 15th, 2009


I am replacing a cisco 1751 router with the new 1841 router.

The WAN side is UP/UP. The fastethrenet side is UP/DOWN. The speed is auto and duplex full. It is configured the same as it was in Cisco 1751.

The Fas 0/0 connects to 3COM switch. The LED on 3com switch is off when 1841 is connected.But on 1841 the LED for fas 0/0 is green.

Any ideas what is happening here?

I have this problem too.
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singhsaju Mon, 06/15/2009 - 12:26

I have already tried hardcoding speed/duplex. The interface is still UP/Down.

Paolo Bevilacqua Mon, 06/15/2009 - 13:28

That is strange, other than trying other IOS I wouldn't know what to suggest. Perhaps the TAC has information on the issue.

pompeychimes Mon, 06/15/2009 - 18:56

Try a ethernet loopback plug in the Router ethernet port. See if it comes up.


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