Adding replacement 3750X stack switch

Answered Question
Sep 25th, 2013
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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

Correct Answer by bgroves about 3 years 10 months ago

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.... :-)


Correct Answer by CSCO12052693 about 3 years 10 months ago

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

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Joseph W. Doherty Wed, 09/25/2013 - 09:14
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Disclaimer


The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.


Liability Disclaimer


In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.


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).

Dante Verastegu... Wed, 09/25/2013 - 09:38
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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

Correct Answer
bgroves Wed, 09/25/2013 - 11:07
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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.... :-)


Dante Verastegu... Wed, 09/25/2013 - 17:10
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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,

Joseph W. Doherty Wed, 09/25/2013 - 16:01
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Disclaimer


The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.


Liability Disclaimer


In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.


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.

Correct Answer
CSCO12052693 Wed, 09/25/2013 - 09:30
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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

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