Sep 06

Cisco StackWise – 3750 Stacking Issue

We found a really weird issue with a version of IOS on our Cisco 3750 stack. A stack of five 3750 switches was created and configured for one switch to be master of the stack and another stack member as secondary master. However, as soon as you reboot the stack, the switches come back online and form two different stacks with two different stack master. Even thought the switches are cabled to form one stack they virtually form two stacks. If you reboot them again, they might form three stacks. This is explained in the figure below

To resolve this we downgraded the IOS from 12.2(53) SE2 to IOS 12.2(50) SE5.

IOS Causing Issue : 12.2(53) SE2
IOS Fixed the Issue: IOS 12.2(50) SE5


  1. Fred

    Is there a defect associated with the bad stack on 12.2.53?

    1. xerunetworks

      Yes, if you try to merge two stacks or try to add new switches to current stack then it splits these into two stacks. 

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