topic Re: Adding replacement 3750X stack switch in Switching

Adding replacement 3750X stack switch

Dante Verastegui Noriega — Thu, 07 Mar 2019 23:40:44 GMT

Hi everyone!

I need some help with a stack configuration!

A client had two 3750X 24 ports IP Base switches configured in stack (I didnt do the config). Everything was working perfectly but the slave switch failed and they had to replace it for a new one. Same switch, same IOS, same version, same everything.

So now my doubts are, if the master is still working, do I have to configure anything on the new switch that will be a slave? Or its just plain and simple, to connect the stacks and thats it?

I havent configured anything on the new switch since Im trying to learn about how stack exactly works. So far what i know is that you dont need to configure anything on the new stack member since the master syncs the configuration, but does not configure anything, means exactly that? not even passwords or usernames or something?

Please i would appriciate your help!!

Thank you!

Sincerely

Dante V.

PS: Im attaching the config for the master switch

Re: Adding replacement 3750X stack switch

Joseph W. Doherty — Wed, 25 Sep 2013 16:14:16 GMT

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Posting

If replacement is exactly the same model, and has same IOS, and is in a default configuration, it should "picked up" configuration for prior stack (I believe).

Re: Adding replacement 3750X stack switch

CSCO12052693 — Wed, 25 Sep 2013 16:30:53 GMT

If I can remember, it copies everything over at bootup (the whole config file). I'd recommend hard setting a master for the slaves instead of letting it decide. you can view with a show switch. I believe set the priority for the master is:

switch stack-member-number priority new-priority-value

Here is a good link though:

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_example09186a00807811ad.shtml

Adding replacement 3750X stack switch

Dante Verastegui Noriega — Wed, 25 Sep 2013 16:38:05 GMT

Hi Joseph,

It is the same, However, when I do a show switch (on the new replacement switch) it shows me that its a master, do they come like this as default?

If i connect it to the Master switch of the network, would it become a slave automatically? Or do I have to configure something else?

I'd appriciate your help

Sincerely

Dante V

Adding replacement 3750X stack switch

bgroves — Wed, 25 Sep 2013 18:07:05 GMT

My advice after managing hundreds of stacks of stackable switches.

ALWAYS force the switch number and priority.

When adding or replacing ensure you have same code, set the switch # and priority and plug it in no hoping or guessing required.

Set the switch you want as master as sw #1 and pri 15 the next one as 2 and 14 and so on.

Always set these parameters on any new stack member, especially if you are reusing one formerly used for something else.

You plug in a switch with a better priority and your stack now has it's config.

sh sw

Switch/Stack Mac Address : 001c.5812.4080

H/W Current

Switch# Role Mac Address Priority Version State

----------------------------------------------------------

1 Master 001c.5812.4080 15 0 Ready

2 Member 001a.6d26.0a00 14 0 Ready

3 Member 001a.6d79.0f00 13 0 Ready

4 Member 001d.45e4.2c00 12 0 Ready

5 Member 001d.45fb.0000 11 0 Ready

Being somewhat OCD they are physically stacked in that order as well.

OK climbing off my soapbox now.... 🙂

Re: Adding replacement 3750X stack switch

Joseph W. Doherty — Wed, 25 Sep 2013 23:01:51 GMT

Disclaimer

Liability Disclaimer

Posting

A 3750 switch running by itself will always be a master, as it's a "stack" of one.

Brian's suggestion about setting the replacement's switch number is excellent. As to the suggestion of setting the switch's priority, when you add the replacement switch to the stack, there shouldn't be a stack election so the existing master would be retained even if the replacement switch had a higher priority. However, if you did have a stack election, like powering on both switches at the same time, setting the priority higher on the existing master would insure it wins the stack election.

There a bunch of documentation about 3750 stack management on Cisco's main web site, so you might also look there.

Re: Adding replacement 3750X stack switch

Dante Verastegui Noriega — Thu, 26 Sep 2013 00:10:43 GMT

Thank you!

I set up the priority of the master to 15 and the new one to 1 and it worked!

Everything is running great now

Sincerely,