Switch Stack links bouncing after upgrade.

[devingu]

Hello, 

I'm reaching out as I recently performed a Firmware upgrade on a WS-C2960S-24TS-L swtich stack (2 switches) from software version 12.2(55)SE3 to 15.2(2)E9. The upgrade appeared to go well but once the switches fully booted I saw our redundant link began bouncing. This caused several of the servers as well as the management SVI to start reporting significant packet loss. I was able to bypass this by removing the molex cable from ports 2. Is there any known bugs for the C2960S platform that would cause what I'm seeing?

May 26 16:04:41.991: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has changed to state UP
*May 26 16:04:42.107: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UP
*May 26 16:04:42.988: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has changed to state DOWN
*May 26 16:04:43.108: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN
*May 26 16:04:44.110: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UP
*May 26 16:04:45.111: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN
*May 26 16:04:49.111: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UP
*May 26 16:04:50.107: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN
*May 26 16:04:52.991: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has changed to state UP
*May 26 16:04:54.108: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UP
WOODLAND_DR_SW#sh switch
Switch/Stack Mac Address : 0008.3081.ba80
H/W Current

Switch# Role Mac Address Priority Version State
----------------------------------------------------------
*1 Master 0008.3081.ba80 1 5 Ready
2 Member 0008.30eb.ee80 1 5 Ready

WOODLAND_DR_SW#sh switch detail
Switch/Stack Mac Address : 0008.3081.ba80
H/W Current
Switch# Role Mac Address Priority Version State
----------------------------------------------------------
*1 Master 0008.3081.ba80 1 5 Ready
2 Member 0008.30eb.ee80 1 5 Ready

Stack Port Status Neighbors
Switch# Port 1 Port 2 Port 1 Port 2
--------------------------------------------------------
1 Ok Down 2 None
2 Ok Down 1 None

[Reza Sharifi]

Hi,

Usually, a software upgrade should not effect the stacking cables. You may want to make sure the stacking cable is in the slot securely. Also, try a different stacking cable.

HTH

[devingu]

I'll give that another try. are these molex cables hot swappable? or do I need to power down when adding/removing cables? I will try that during a maintenance window if I need to power down.

[Reza Sharifi]

You should not need any reboot/shutdown when replacing the stacking cable. That said, I would do it during a maintenance window just in case something unexpectedly goes wrong.

HTH

[Leo Laohoo]

Cold reboot the entire stack.