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New Member

Catalyst 3750 replacement procedure when in a stack

1. If I want to replace one switch in the stack (slave switch) in a stack of 4 switches, with a spare do I have to first upgrade my spare 3750 to the same IOS as the other members in the stack or will the current stack master automatically copy the IOS from itself to the new replaced switch.

2.If the answer is that the current stack master will automatically copy the IOS from itself to the new replaced spare, then is the answer the same whether the new spare is a higher or lower version of IOS than the current master. Or will I get a version mismatch error under some circumstances.

3. Lastly will the config get automatically copied from the master to the new spare.

I have read information at the following links


but reading is not the same as asking for the input of someone who has done this practically.

In some of this forum entries it says to copy the IOS first into the spare switch and also to copy the template into the spare switch. What template is it talking about.

Cisco Employee

Re: Catalyst 3750 replacement procedure when in a stack

Ok, you would get as many suggestions & ideas as many documents you read. I have done around 50's if not 100's of stack upgrades & I would give you the best & easiest way to upgrade the stack without ending up with a down core.

1) The new spare switch that you want to add to the stack, is not on the network obviously, so the best is to upgrade or downgrade it to the version that is currently running on your stack.

2) Using the command 'switch 1 priority 1' command make the spare switch a lower priority than your master. If your master switch has a priority of 1, then use the command 'switch priority 15'. The higher the priority of a switch the better chance it has of becoming the master. We do this step so that in no circumstance the new spare switch becomes the master.

3) Make sure that the new spare switch is powered off.

4) Connect the stacking cables between the spare switch & the master switch.

5) Once the cables are connected power on the new switch

6) It should gracefully join the stack as a member

You do not have to worry at all about copying the configuration or template or anything. In a stack the configuration is on the master so you DO NOT need to do anything with the configuration of the spare switch.

Hope that helps!!

New Member

Re: Catalyst 3750 replacement procedure when in a stack


My experience with replacing a switch in a stack is as follow.

I change de switch number and priority of the spare switch in the following order

switch [stack-member-number] priority [new-priority-number]

switch [current-stack-member-number] renumber [new-stack-member-number]

Then I reload the switch and after start up I remove the following command

no switch 1 provision [Type] (look up with show run )

and save the config.

Then I take of the power and install the switch into the stack.

After connecting the power, the switch will be added to the stack as follow.

The switch is recognized and the software will be corrected bij the stack and be taking into account.

If the switch is not accepted, you will see with show switch that the switch stands with a Version Mismatch.

With this command you can copy the software from another stack member:

archive copy-sw /force-reload /destination{destination_switch_number} {source_switch_number}

The /force-reload command will reload the only de destination switch after copiyng the software.

In some cases you have to change the SDM template of the switch. But if you change the switch for a similar switch then this will not happen.

When I follow this procedure, I never had a rebooted stack or a mesh-up config.

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