questions regarding Cisco StackWise

I have a following Cisco StackWise setup:

Switch Ports Model              SW Version            SW Image                 
------ ----- -----              ----------            ----------               
*    1 28    WS-C3750G-24TS-1U  12.2(53)SE1           C3750-IPBASEK9-M         
     2 28    WS-C3750G-24TS-1U  12.2(53)SE1           C3750-IPBASEK9-M         
     3 12    WS-C3750G-12S      12.2(53)SE1           C3750-IPBASEK9-M

As you can see, switch 1 is selected as a stack master. Is there a service interruption if I do:

switch 1 priority 5
switch 2 priority 15

..which sets the priority of the first switch lower than the second one? In addition, when does the stack-master election occur? According to Cisco documentation, it is a part of the bootup process, but is there a way to manually force stack-master election once I have changed the priority?

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Comments

*BB*

You can change the priority of whichever switch you want to be the master, but I believe you will need to reboot the stack in order for it to take effect.

cisco_trooper

*BB* wrote: »

You can change the priority of whichever switch you want to be the master, but I believe you will need to reboot the stack in order for it to take effect.

This is correct. I've got multiple 3750 stacks.

m4rtin

*BB*, cisco_trooper:

ok, so there isn't any other way to evoke master election other than reboot the whole switch stack? So basically following commands:

switch 1 priority 5
switch 2 priority 15

..will prefer the switch 2 to become a master once the next election takes place, but once the whole stack isn't rebooted, nothing happens?

cisco_trooper

Well, I suppose you could disconnect the stack master then reconnect it within the stack election window. Should be 20 to 60 seconds if I remember right.

cisco_trooper

Ok. Stack master election from Troubleshooting Switch Stacks - Cisco Systems

A new stack master is elected when you:
•Power off, disconnect, or reboot the current stack master.
•Power on all switches in a new stack at the same time.
•Reboot all switches after you manually change the stack member priorities by using the CLI.
•Connect a powered-on stack to another powered-on stack merging two separate stacks merge into one.