Switch ordering in a 3750x stack

[keithsauer507]

Hello,

Does it matter which switch in a 3750x stack is the master (switch1)?  I have two 3750x's, one a 48 port poe and another a 24 port poe.  They are in a stack.  Now the 48 port is on top and stacking cables connected to the 24 port on bottom.  Of course the bottom switch becomes switch 1 and has interfaces Gi1/0/1 through 1/0/24.

They are both running 12.2(55)SE8 C3750E-UNIVERSALK9-M (ipbase).  They are in staging now going to a new remote branch office.

I guess it really doesn't matter which switch is 1 and which is 2 does it?  When we get into the new office and I break this equipment down, then I will rack the 24 port on top and the 48 port on bottom then if that makes more sense.

Or I could change it, I guess by altering this line in the config right

switch 1 provision ws-c3750x-24p

switch 2 provision ws-c3750x-48p

to

switch 1 provision ws-c3750x-48p

switch 2 provision ws-c3750x-24p

Or do you think a 24 port as the master would be better.  If it has less ports to manage, maybe more CPU cycles to do master stack related things?

[Reza Sharifi · Accepted solution]

Hi,

It really doesn't matter, as long as both have the same image and license level. If the switches are sitting right on top of each other, for easier access, I would put the 48 port at the top and call it master and give it priority 15.  The 24 port can be default or a lower priority.

I also put a sticker on them something like:

switch-1 master

switch-2 member

HTH

[keithsauer507]

Ok thanks, good to know it doesn't really matter.  Because of how they will be situated in the rack when we move to the new office, I changed the priority and did some renumbering.  After a few reloads I have it exactly how I want it.  Top switch is 48 port and master, bottom switch is 24 port and member.

[Joseph W. Doherty]

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

Cisco recommends the stack master not host stack uplinks.  As best as I can tell, this is to try to keep some CPU processing off the stack master.  So, in theory, having the master on the switch with the fewer ports might be "better" too.  (Also if only one uplink, keep it off the stack master.)

As higher stack priority doesn't preempt (when a member joins a stack), you cannot guarantee which switch is the stack master unless you manually oversee the stack election.  So, personally, I don't try to control it.  Also, if the switch stack is forwarding in hardware, as it should, I wouldn't expect such forwarding to matter much to the switch running as master, i.e. available CPU cycles, for master needs, should be the about the same on any stack unit.

[keithsauer507]

Ok, well its not so much where I care which one is the stack master... its the switch numbering I'm really more concerned about.  The way the patch panels and rack is setup, when it goes to its home the 48 port will be on top and the 24 port will be on bottom.  So logically I want the 48 port on top to be Switch 1.  I did make this change with the switch 1 renumber 3, wr mem, reload then sw 2 renumber 1, switch 3 renumber 2, wr mem, reload.  Then unprovisioned the "temporary" switch 3 from the config.

So now I have what I want.  As far as which one is the master, I can always just alter the priorities.

To be honest, its a remote branch and the traffic will be small.  Were talking VOIP calls, print jobs, office documents from a file server, and the connection to the HQ is a 10mbps WAN with a 4G LTE backup off a Cisco 2900 series router.

Core applications mostly run in the web browser, and other applications require small bandwidth (were talking kbps, not mbps).