Cisco 3750 stack replacement

bstrubeTD3 · ‎05-28-2020

I have read the Cisco 3750 documentation about replacing stack members, but I want to make sure I understand completely. Ihave a stack member that is starting to fail, it is not the master, and I have a 3750 from a different site with the same license and SW version. It is the same model as the one I am replacing.

From what I read I need to do the following:

1. Power off the failing member.

2. Remove the stack cables from the failing switch. This happens to be the last switch in the stack.

3. Remove the provisioned switch from the config ( 3750(config)# no switch 7 provision ws-c3750-24ps)

Here is my question:

I will be replacing with a switch that already has a configuration on it. Do I erase this configuration before I add it to the stack?

Or do I just have to change the switch 1 provision ws-3750x-24ps to switch 7 provision ws-3750x-24ps? Or do I do the switch 7 provision ws-3750x-24ps on the stack?

My thinking is that I need to erase the config on the switch I will be adding and do the switch 7 provision ws-3750x-24ps on the stack. Is this correct?

Reza Sharifi · ‎05-28-2020

My thinking is that I need to erase the config on the switch I will be adding and do the switch 7 provision ws-3750x-24ps on the stack. Is this correct?

That is correct. Yes, I would erase the config before adding the new switch to the stack.

HTH

Martin L · ‎05-28-2020

Just to be sure you can erase start config and vlan.dat files on old sw. once you in switch mode, you can also change switch stack number to 7 and change priority to 1.
Most importantly Make sure your current Mater sw and backup master have higher priority then switch u adding. 15 for current master; 14 for back up. you do not have to remove switch 7 provision ws-3750x-24ps if it is the same model.

Normally, new switch will download config from Master during sync phase unless new sw priority is higher then current Master. If new sw with no config or bad config has priority 15, it may take over and your current stack switches will change configs which is very bad!

Switch provision # comes from last # available. Not 100% sure but Command switch # provision ws-3750x-24 maybe skipped. Sw will add that command once new member joined stack OK.

Regards, ML
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mohammedshahidali88 · ‎05-28-2020

Better to add the New Switch in the Stack and once it is up and running you can renumber the Switch.

Leo Laohoo · ‎05-28-2020

@bstrubeTD3 wrote:

Remove the provisioned switch from the config ( 3750(config)# no switch 7 provision ws-c3750-24ps)

If the replacement is the same as the faulty unit then there is no need to do this.

NOTE: A stack size of 7 is really large. I wouldn't recommend stack size of 7 and higher as there can be some performance issue that usually creeps up when the uptime is high.