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Native stack links are flapping on Summit x460's

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TitleNative stack links are flapping on Summit x460's
Symptoms
Native stack links go down and back up on Summit x460's at a fast rate.

Logs:
09/24/2014 11:16:21.43 <Info:HAL.Port.Info> Slot-2: Stacking port 3:1 link down.
09/24/2014 11:16:21.43 <Info:HAL.Port.Info> Slot-2: Stacking port 2:2 link down.
09/24/2014 11:15:06.43 <Info:HAL.Port.Info> Slot-2: Stacking port 3:1 link up at 10Gbps.
09/24/2014 11:15:05.58 <Info:HAL.Port.Info> Slot-2: Stacking port 2:2 link up at 10Gbps.
09/24/2014 11:15:02.43 <Info:HAL.Port.Info> Slot-2: Stacking port 3:1 link down.
09/24/2014 11:15:02.43 <Info:HAL.Port.Info> Slot-2: Stacking port 2:2 link down.


In some cases this can cause one of the switches in the stack to reboot due to dual-mastership.
This can be seen when checking the local logs of the slot that rebooted.

04/23/2015 18:54:30.05 <Warn:DM.Warning> Slot-2: Slot-1 FAILED (1) Dual Master
04/23/2015 18:54:30.05 <Crit:NM.NodeStateFail> Slot-2: Slot-1 has failed for the reason of "Dual Master".
Environment
  • Summit x460 in a native stacking topology
Cause
Stack link flaps occur due to the X460 detecting a transient local fault and sent a remote fault to the peer. The peer declared link down when detecting remote fault.
Resolution
1. Upgrade EXOS to a version that includes the change for xos0059131, and submit the below command to change the debounce timer to 150ms.  If there are still stack link flaps move the debounce timer to 300.

configure stack-ports [<stacking-port-list>] debounce time [default | <milliseconds>]

Example:

configure stack-ports 2:2 debounce time 150

2. Confirm Debounce settings are changed.

show stack-ports debounce
Additional notes
xos0059131 is included in the below code and later:
  • 15.6 +
  • 15.5.2.9-patch1-1
  • 15.4.2.8-patch1-3
  • 15.3.4.6-patch1-14

 

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