Stack port down on 3750

[jcounsell1222]

have a cable i think is bad, is it possiable to switch the cable out without causing any downtime to the switch or connected devices?

HQ-1st-Flr-Stack#show switch stack-ports summary

Switch#/  Stack   Neighbor   Cable    Link   Link   Sync      #         In 

Port#     Port              Length    OK   Active   OK    Changes   Loopback

          Status                                          To LinkOK         

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

  1/1     Down      None    50 cm     No     No     Yes        3        No

  1/2     OK         2      50 cm     Yes    Yes    Yes        1        No

  2/1     OK         1      50 cm     Yes    Yes    Yes        1        No

  2/2     OK         4      50 cm     Yes    Yes    Yes        1        No

  3/1     OK         5      3 m       Yes    Yes    Yes        1        No

  3/2     Down      None    50 cm     No     No     No         3        No

  4/1     OK         2      50 cm     Yes    Yes    Yes        1        No

  4/2     OK         5      1 m       Yes    Yes    Yes        1        No

  5/1     OK         4      1 m       Yes    Yes    Yes        1        No

  5/2     OK         3      3 m       Yes    Yes    Yes        1        No

HQ-1st-Flr-Stack#

[mahmoodmkl]

Hi
AFIK u need to do it by shutting down the switches


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[Gregory Snipes]

I do not know of any reason why you would need to shutdown a 3750 stack to replace a cable. You can even hot swap switches in and out of the stack without shutting down the whole stack.

[Gregory Snipes]

Yes, you have connected them redundantly so you can switch the cable out no problem.

[jcounsell1222]

ok, will the devices that are connected to the one 3750 lose connectivity? or will they be fine because of the secondary connection on the same switch.

[Gregory Snipes]

Removing the stack cable will have no impact. It will be exactly like it is now as you have no connection on the link that you belive has a bad cable. Just do not pull any of the other cables.

[jcounsell1222]

i figured as much, thank you. i will test this today and get back to this thred with the results.

[jcounsell1222]

tested the stack cable on a brand new switch and it detected the cable on both stack ports. at this pint i know its one of the switch stack ports that are the issue. i was wondering if there was a way to see if the port was administrativly "down".

[Gregory Snipes]

This document goes over a lot of the details on stacking if you want to give it a read, but the answer is no. The stack ports are always enabled. If you have confirmed that the cable is good you likely have a hardware failure and will need to contact Cisco to have the hardware replaced.

[jcounsell1222]

i figured as much. now i just need to figure out witch switch has the bad stack port and will need downtime to test that.

[Gregory Snipes]

Online port diagnostics should provide results for the stack ports as well. Please see this document for more info on running them.

[jcounsell1222]

i tested both switches with the following command:

diagnostic start switch # test non-disruptive and they both came back with a passed result. im guessing that this test is not in depth enough to test weather the stack ports work or not. i know the cable its self is good. will need to run a more in depth test to figure out what is going on at this point.

[hobbe]

Hi

It seems like you have the same problem that I have had some experience with..

What I do is generally just loosen the cable and replace with a new cable if i have one.

That normally does the trick.

If you have no new cable to use then just remove the cable and flip it over so that the end that was in switch 2 now points to switch 1 and attach it again.

Most of the time this fixes the problem, it seems like the cable is very sensitive to be placed a little out of place.

background infor that might be good to have.

The stacking cables actually work by chaining together the different stacks in two bi directional rings.

So when you break the stack ring by removing the cable the ring just lost half its speed and the redundancy to have two ways to move data between the different switches,

Thats why you can remove and replace the cable without the stack breaking apart.

Good luck

HTH

[jcounsell1222]

This did not solve my issue. I'm going to test the cables tomorrow to make sure they work. If they are fine I'll need to schedule downtime to test the switch.


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[Matthew Frederick]

can you post the output of "sh int x/x" (whichever one is in question)? this might help us troubleshoot further.