Stack port flapping

Unanswered Question
Jul 9th, 2007

Hi,

we have just discovered some error messages indicating stack port flapping.

we have swapped stack cable, but error messages wouldn't stop.

It is a 2 x 3750 cisco switches stack, and it has been up and running for quite a while. The redundant stack port is also working fine.

error messages look like this:

Jul 10 16:07:48.903: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has ch

anged to state UP

Jul 10 16:07:50.455: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has ch

anged to state UP

Jul 10 16:07:51.462: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has ch

anged to state DOWN

Jul 10 16:07:51.923: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has ch

anged to state DOWN

Jul 10 16:07:52.469: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has ch

anged to state UP

I searched on cisco website but didn't seem to find any solutions to it.

Any input would be much appreciated.

Cheers,

YingJie

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Amit Singh Tue, 07/10/2007 - 02:54

The error message means that one of the stack connections is flapping,going up-down constantly.

According with the messages, the connection we are having problems with is the one between switch 1 stacking port 1 and switch 2 stacking port 2. This error message could be caused by a faulty stacking cable or a faulty stacking oort. If possible, I would like you to remove the stacking cable connected on these ports and then clear the log and verify if the message stops. Then, if you had a spare stacking cable,it would be a good idea to try it out.

If you do not have a spare cable, in order to determine if the problem is with the cable or the a stacking port it self, we would need to swap the stacking cables around, and if the error message now points to the other two ports, it would be definitively a problem with the stacking port itself.

HTH,Please rate if it does.

-amit singh

yingjiecisco Tue, 07/10/2007 - 18:36

Hi Amit,

Thanks for the reply.

- I have swapped a brand new cable, error persists.

- Did what u suggested... removed the cable and error did stop... however, isn't this expected because nothing was plugged into the port hence it wouldn't bother checking?

cheers

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