Catalyst 3850 switchstack, stack port status down

[corpengineer818]

We have (4) Catalyst 3850 switches, configured as a stack. 

Seems that one or both stack ports on switch 3 and 4 are down.

How do I troubleshoot this?  I don't see any commands to re-establish the stackports.  All the commands I see only report on status of the switchstack. 

I already rebooted the switchstack.

Any help would be much appreciated.

Please see output below.

Thank you.

Catalyst3850Stack#show switch neighbors
  Switch #    Port 1       Port 2
  --------    ------       ------
      1         2             4
      2         3             1
      3        None           2
      4         1            None

Catalyst3850Stack#show switch detail
Switch/Stack Mac Address : a.b.c.d - Local Mac Address
Mac persistency wait time: Indefinite
                                             H/W   Current
Switch#   Role    Mac Address     Priority Version  State
------------------------------------------------------------
*1       Active   a.b.c.d     15     V03     Ready
 2       Standby  a.b.c.d     14     V03     Ready
 3       Member   a.b.c.d     13     V03     Ready
 4       Member   a.b.c.d     1      V02     Ready

         Stack Port Status             Neighbors
Switch#  Port 1     Port 2           Port 1   Port 2
--------------------------------------------------------
  1         OK         OK               2        4
  2         OK         OK               3        1
  3       DOWN         OK             None       2
  4         OK       DOWN               1      None

[Leo Laohoo]

The only way to troubleshoot this is to do a visual inspection of the stacking cable.  

[corpengineer818]

I unplugged, then re-plugged in the stacking cable in question.  Still, it did not resolve the issue.  The units are only 1 year old, I wouldn't expect the cable to go bad so quickly. 

Anything else I can try at the console? 

Are there any commands to try to re-sync up the switchstack?

Thank you.

[paul driver]

Hello

Try powering down SW3 and SW4 and remove stacking cables

Power up each switch standalone and check for any issues, Then wipe the config and renumber and prioritze each switch.

Power down again and then re-introduce each switch one at a time back into the stack.

res
Paul

[corpengineer818]

Got it, thank you.

Was hoping to not have to take everything down.  Are there any less invasive options, to re-sync these switches back up?

Thank you.

[swasthik_ms87]

Hi,

Did you try replacing the Stack Cable with new one or any other working one ? You could try replacing the stack cable from, say Switch 01 to 02 and try on 03 to 04 and see if that brings the Stack link UP, If Yes, it's issue with Stack Cable. 

If this didn't help, most probably issue could be with Stack Ports on Switch 03 or 04.

I don't really think there is command on Switch console to bring Stack link UP/Down.

Thanks

Swasthik M S

[corpengineer818]

Thank you