Question regarding to 3750 switch stack

[Difan Zhao]

Hi experts,

I have a switch stack. They are the following models and at the following firmwares:

Switch Ports Model              SW Version            SW Image
------ ----- -----              ----------            ----------
*    1 30    WS-C3750E-24TD     12.2(53)SE2           C3750E-UNIVERSALK9-M
     2 30    WS-C3750E-24TD     12.2(53)SE2           C3750E-UNIVERSALK9-M
     3 26    WS-C3750V2-24PS    12.2(53)SE2           C3750-IPSERVICESK9-M
     4 26    WS-C3750V2-24TS    12.2(53)SE2           C3750-IPSERVICESK9-M
     5 12    WS-C3750G-12S      12.2(53)SE2           C3750-IPSERVICESK9-M
     6 12    WS-C3750G-12S      12.2(53)SE2           C3750-IPSERVICESK9-M

Every time I reboot the switch stack the #3 will be elected as master. And yes I have the #1 set the highest priority.

Switch#  Role   Mac Address     Priority Version  State
----------------------------------------------------------
*1       Master 0024.9813.7c80     15     1       Ready
2       Member 18ef.63b1.9980     14     1       Ready
3       Member 18ef.63f1.b300     1      0       Ready
4       Member a8b1.d4a5.ab00     1      0       Ready
5       Member d0d0.fde5.e880     1      0       Ready
6       Member d0d0.fde5.8580     1      0       Ready

I think the problem is that the first two switches take way longer to boot up than the rest so they will miss the "master" election process and that's why they can't be elected. Is there any way to fix this? Like a command to increase the timeout for the election process?

Another question is that if #3 is elected as master, is there a way to make the #1 master again other than rebooting the #3 switch?

Thanks!

Difan

[Reza Sharifi]

Another question is that if #3 is elected as master, is there a way to make the #1 master again other than rebooting the #3 switch?

yes, on switch 3 issue "switch 1 priority 15"

Then

reload slot 3

This will reboot switch 3

HTH

Reza

[Difan Zhao]

Hi Reza,

Thanks for the reply but that will still require the switch 3 to be reloaded. Is there a way to make #1 master without reloading the #3?

Thanks,

[Reza Sharifi]

As far as I the know, there is no way to force reelection without a reboot, or the failure of the master switch.

BTW, the reboot should need to happen very often.  Once you get switch 1 to be the primary that should be good for a long time unless there is hardware failure or IOS upgrade.  3750s are in general pretty reliable switches.

HTH

Reza

[Difan Zhao]

Got it!

So is there anyway to slow down the boot time of the rest 3750 switches so there will be enough time for the first two switches to be up and participate in the master election?

Thanks,

[Reza Sharifi]

There is no command to slow down the boot process.  Maybe what you can do is to turn off all the switches then turn on the master first and after few seconnd turn on the rest.  This way your master boots first

HTH

Reza

[Difan Zhao]

Hi Reza,

We can definitely do this when we are onsite. However this is just in case (etc, upgrading firmware) that we need to reboot it remotely... If there is no better way then I guess I have to get the #3 to reboot again to yeild the master!!

Thanks for the help,