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Cisco Catalyst with StackWise not that wise

Today I attempted to add a Cisco catalyst 3750 to an existing stack of Cisco switches. A stack is a number of sequentially connected switches via the proprietary 16gbps StackWise™ cable. As the advertising story goes adding a switch to an existing stack should be as simple as connecting the switch to the stack via the StackWise™ cable and powering it on. After my experience call shenanigans on StackWise™ technology.

The first thing that happened after hooking up and powering up the new switch was a software incompatibility that apparently prevented it from joining the stack. Turned out the stack master switch IOS version (12.2(25)SEE2) was different from the switch to be added (12.2(35)SE5). The master switch election function attempted but failed at downgrading the IOS of the switch to be added to match its own and so finally the new switch sat there in the stack completely useless.
Switch#  Role      Mac Address     Priority     Current State
———————————————————————————-
1       Member    0000.1111.2222     1         Version Mismatch

*25       Master     3333.4444.5555      1         Ready

I had a choice: Either manually upgrade the stack master and perform a reload on a production stack or manually downgrade the new stack to match.  Business hours and a weekday made that decision easy…downgrading the new switch it was. Here’s how:

  1. Delete the image on the new switch to create room for the older image from the master switch.
    #delete flash1:c3750-ipservices-mz.122-35.SE5
    #delete flash1:c3750-ipservices-mz.122-35.SE5/c3750-ipservices-mz.122-35.SE5.bin
  2. Copy the image from the master switch to the new switch
    #copy flash:c3750-ipservices-mz.122-25.SEE2.bin flash1:
  3. Reload the new switch
    #reload slot 1
  4. Ensure that the all switches (including new switch) will always boot the downgraded image in the event of a failure or power out. To do this I connected directly to the new switch.
    (config)#no boot system
    (config)#boot system switch all flash:/c3750-ipservices-mz.122-25.SEE2.bin

Now everything was working, but it definitely wasn’t automatic or easy.
Switch#  Role      Mac Address     Priority     Current State
———————————————————————————–
1       Member    0000.1111.2222      1         Ready

*25       Master     3333.4444.5555      1         Ready

June 6, 2008

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