3850 switch stack upgrade with minimum downtime

[CiscoNutt]

I was wondering if it is possible to do an upgrade of the individual stack members one at a time?

Is it possible to go from one major release to another doing this?

Is it possible to do this going from one minor release to another?

Is it possible to upgrade one stack member at a time within the maintenance release?

Thanks

[Ashok Kumar]

I was wondering if it is possible to do an upgrade of the individual stack members one at a time?

Ans: Yes you can, but the switch will leave the stack 

Is it possible to go from one major release to another doing this?

Is it possible to do this going from one minor release to another?

Is it possible to upgrade one stack member at a time within the maintenance release?

Ans for all above 3: For Stack configuration to work properly, switches must have the exactly same ISO

Recommendation: If they're many switches in stack,

1. upload the IOS file in all the switches

2. change the boot order in running config by:

boot system flash: <new ios fiile name> 

boot system flash: <old ios fiile name>

3.  take the reload one  by one & copy the running config

4. in this case, basically you would be making the new parallel switch stack by adding the reloaded switch with same config but with new IOS image  

[CiscoNutt]

But wouldn't this mean that I will also need to disconnect the stack cable from the existing stack?  I.e. I would need to be onsite to be able to do the upgrade.

[Reza Sharifi]

There is really no way (that I know) you can upgrade a stack without any down time.

The reason for that is if you try to upgrade one switch at a time and reboot, you will have problems with stacking, meaning each switch becomes a stand alone switch, and now you have different IOS versions installed on different switches.

The easiest way to do this is to have a maintenance window and load the IOS to all switches using .tar file. Once completed, reboot the entire stack.

http://www.cisco.com/c/en/us/support/docs/switches/catalyst-3750-series-switches/64898-upgrade-3750-stack.html#mupgrade

HTH 

[mbrunton77]

Would you say the only downtime for the switch, would be the time it takes to reboot?  Say like 5 minutes or so?

[Reza Sharifi]

That is correct. The 3850 takes about 5 to 6 minutes to reboot when you unplug the power core and plug it back in.

HTH

[Florin Barhala]

Hi guys,

I am planning to buy a pair of 3850 for one location where redundancy is required. Basically I have two FWs running VRRP and each connects downstream to one of the two switches.

Now if I want to update it the 3850 stack without traffic disruption while both of the two switches are cabled/connected identically what do you think about this sequence:

1. Have console access on each SW

2. Upload on the flash of each SW the new image

3. interface range gi2/0/1-48 

shutdown

At this moment as all connections are duplicate there should be no outage. If by any mean I close the ports of the switch used by the active firewall, then a firewall switchover should be triggered by the ports shutdown.

3.1 I think I should also shutdown the stacking ports on switch 2 at this moment, too.

4. Using console on switch 2, install new image and reboot the switch

Now how can I convince switch 2 to become stack master when enabling back the stack ports? After IOS upgrade I would like/need to shutdown all ports on switch 1 and switchover all traffic on switch 2. But to avoid an outage I would need for small period of time to have both switches on.

Thoughts?

Thanks in advance,

Florin.