3750 Stack Stack_link_Change

Unanswered Question
Jul 9th, 2007

We have a 3 switch stack that starting spewing the folowing log entries late last night repeatedly:

152342: Jul 9 14:03:26 EDT: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has changed to state DOWN

152343: Jul 9 14:03:27 EDT: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has changed to state DOWN

152344: Jul 9 14:03:28 EDT: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has changed to state UP

152345: Jul 9 14:03:30 EDT: %STACKMGR-6-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has changed to state UP

The switches in question are:

Switch Ports Model SW Version SW Image

------ ----- ----- ---------- ----------

* 1 52 WS-C3750-48P 12.2(25)SEB C3750-IPSERVICESK9-M

2 52 WS-C3750-48TS 12.2(25)SEB C3750-IPSERVICESK9-M

3 52 WS-C3750-48TS 12.2(25)SEB C3750-IPSERVICESK9-M

This stack has been up for over a year so what would cause this all of a sudden like this?

Thanks in advance.


I have this problem too.
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Overall Rating: 3.5 (2 ratings)
yingjiecisco Mon, 07/09/2007 - 22:24

Hi John,

It seems that i have just encountered the same problem... We have swapped a brand new stack cable and reseated the plug, nothing seemed to have helped.

would love to know how things progress on your side... have you found a solution yet?



guruprasadr Mon, 07/09/2007 - 22:34

HI John,

It seems like Stack Updates are not propagating in a right way.

Pls Check your Stack Cable Quality / Try changing your Stack Cable.

Pls Rate if Helps

Best Regards,

Guru Prasad R

Amit Singh Tue, 07/10/2007 - 02:27


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

John Rumball Tue, 07/10/2007 - 05:01

Thank you all for your replies to my post.

Shortly after posting this, I noticed two ports in err-disable mode. I shut these ports down and then observed that the errors suddenly stopped appearing in the logs. I thought I had the problem solved... until an hour later when they started up again. I immediately checked again for ports in err-disable mode but could not find any. Now I was puzzled.

Since the errors did not seem to be affecting the performance of the switch, I decided to leave it for awhile until I heard back from this post if at all. This morning I checked the switch and the errors are nowhere to be found... they must have stopped sometime during the night without any intervention on my part.

Thanks again for attempts to help.


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