Upgradation of WS-C3750X-48T-E from 12.2.(55)SE5 to 15.0.2-SE9

[Vikas Gundu]

Dear Team,

Customer had a concern that he want do upgrade the L3 device with minimum downtime.

Current version running is 12.2 and upgrading to new version 15.0.2.

He is concern of zero downtime with respect to access Switch.

He has 2960 sw at a access later and has etherchannel configured towards L3 (i.e. one link goes to SW1 and other link goes to SW2). This L3 switches are stacked.

Now he is planning to load the image in master and slave.

He will reboot only the master SW1 and now the stack will break and traffic of 2960 will go from Sw2.

After SW1 comes up they will reboot SW2 and now the traffic of 2960 will go from SW1.

After both are on the same version he will form the stack of both the Switches so that user dont face any issue or we can upgrade with minimum downtime.

Pls let me know whether I can go with this procedure.

Pls find the attached for the network diagram.

Thanks in advance

Regards,

Vikas

[Joseph W. Doherty]

I don't recall the 3750X stack supporting a rolling upgrade (at least in the 12.x IOS family), which is what your customer is attempting to accomplish.

If it doesn't, you could break the stack into two independent units, and upgrade them individually, minimizing downtime. Of course, you would also need to stop using the dual Etherchannels between the 3750X stack and the 2960 edge devices.

Once both switches are upgraded, you could reform the stack.

The above would be a lot of work, but it might be the only way to provide almost zero downtime.

BTW, upgrading a 3750X from 12.2 to 15.x might be much more time consuming then normal, as a flash upgrade might be involved. If so, a device reboot might take 15 to 20 minutes.