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New Member

Rolling Stack Upgrade on 3750X switches


Guys, I am really new to all this. I was given the task of upgrading a stack of 2  3750X switches running IOS v 12.2(55)SE4 to version 15.0.1-SE3. Why this version and not a newer one? Well, this stack is in a production environment and sits between an esxi hosts, a sql cluster and an EqualLogic SAN; and on the compatibility matrix of the SAN, this is the required one. These devices/hosts are not using LACP, they have nic teams but none of the teams are configured to use LACP. 

The stack has 4 Uplinks that are set as L2 - NO-LACP PortChannel, they go to another stack of 2 extreme L3 switches, that provide connectivity to the lan). It goes as follow:

2 ports from the cisco switch 1 go into member 1 and 2 ports of the extreme stack

2  ports from the cisco switch 2 go into member 1 and 2 portsof the extreme stack


I would like to do this upgrade the least disruptive way possible for my esxi hosts and sql cluster (Cant shut them down).

I went seeking help from cisco TAC and they sent me these 2 links to guide me through the upgrade process, but I ended up really confused even though it seems to be a really straight forward process.



The first link (3750 Series Switch Stack IOS Upgrade - Automatic (.tar image)) mentions the upload image process but it is not clear if it will reboot one member at a time and not both.

The 2nd link(not my current IOS), on the other hand, talks about portchanel with lacp enabled which I dont have.

Which path should I follow?

Your help is greatly appreciated!








  • Storage Networking
Hall of Fame Super Gold

Firstly, when you want to

Firstly, when you want to upgrade a stack of switch, you will need outage because you need to reboot the switch.  Now I've got a bigger surprise for you (even TAC didn't mention) ... You're going from 12.2(55)SE5 to 15.0, this means your IOS upgrade will also include an automatic bootstrap upgrade.  This bootstrap upgrade will take a good 35 minutes.  


Secondly, unless you want stability, I'd recommend you upgrade to 12.2(55)SE9.  


Third, if you want to upgrade in a more simplistic manner, the best method is to use the old method command:  


archive download-sw TFTP://<TFTP IP address>/IOS_filename.tar

New Member

Thanks Leo,So basically you

Thanks Leo,

So basically you are saying I cant do this upgrade 1 switch at a time like RSU states. And having stack is useless in terms of HA.

One of the thing they brag about is the "Cisco StackWise Plus technology on Catalyst 3750-X switches", which advertises, quoting here "Rolling stack upgrade to minimize network disruption when the members of a switch stack are upgraded one at a time."

I know I have to reboot the switch, but you would think that having a stack with multiple members will allow you to do this with almost zero disruption to your hosts (note: all my hosts and sql cluster servers have multiple paths going across the 2 switches in the stack). 

I dont care if it takes 2 hrs to complete the upgrade as long as it is 1 switch at a time ;)

Secondly, unless you want stability, I'd recommend you upgrade to 12.2(55)SE9.  

Like I mentioned, the IOS version will be guided by the compatibility matrix of the SAN connected to it. Thanks for the heads up though.

Thanks again.


Hall of Fame Super Gold

Let me put it this way ... If

Let me put it this way ... If you want to upgrade/reboot your stack of switches one-at-a-time, you can.  You can use RSU or you can use the old fashion method of manually telling the stack which switch member you want to reload first.  


I cannot say which is recommended for you because I don't know how many uplinks are distributed between your stack.  I don't know how your SAN hosts are distributed between your stack.  I don't know how your SAN will run if one of your switch stack fails.  Too many things to consider.  


Your call on what IOS you want to settle, however, I strongly recommend you review the Release Notes.  


FYI:  SAN switches and Catalyst 3K switches don't mix.  Pay close attention to your "Packet Output Drops" counters on your downstream interfaces (facing your SAN).  If they increment, this is not good.

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