upgrading IOS on a stack

[waqas gondal]

Hi,

Is it possible to upgrade an image on a switch that is part of a stack without having to reboot the whole stack?

Say for example if I have 2 3650s or 2 3750X switches in a stack and I only wanted to upgrade the IOS on 1 switch in the stack at a time without reloading everything at once.

Regards,

Waqas

[Leo Laohoo · Accepted solution]

Is it possible to upgrade an image on a switch that is part of a stack without having to reboot the whole stack?

Not possible.  If you don't reboot the entire stack how can the stack load the new IOS?

Say for example if I have 2 3650s or 2 3750X switches in a stack and I only wanted to upgrade the IOS on 1 switch in the stack at a time without reloading everything at once.

This can be done, HOWEVER, the switch with the new IOS will not be able to join the stack until the master switch gets rebooted.

[waqas gondal]

Thanks Leo

[Leo Laohoo]

Thanks for taking the time to rate our posts. 

[Joseph W. Doherty]

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Posting

As Leo has described, every stack member needs to reload in order to run a newer IOS.  (Of course, you can upgrade the IOS in a stack members flash without reloading the switch, but then its not yet running that image.)

Starting with release 58, 3750X stacks have a new feature, rolling stack upgrade (RSU), which tries to minimize the impact of upgrading IOS across stack members.