Hello - I am looking to upgrade from 5.1.1 to 6.1.?(3). Depending on the Cisco TAC I get different suggestions - wish they were more consistent. Anyone that has gone from 5.1(1) to 6.x could you provide the path? I cannot go direct from 5.1(1) to 6.1.3 so I need an intermediate step. Could go direct to 6.1.1 and then to 6.1.3 or 5.1.1 to 5.1.3 and then to 6.1.3. I am beginning to read thru the release notes as well as the bugs each may have.
I have done both. My recommendation to you is that if you are going to 6.1.3, you might as well go to 6.1.4 right after.
Here is what upgrades i have done:
Gone from 5.1.1 to 5.1.3
and then from 5.1.3 to 6.1.3
and then from 6.1.3 to 6.1.4
Main thing to remember here is do your publisher, reboot it and make sure it is stable. After that, you can do your subscribers. Also make sure that you dont make any config changes to your call manager while doing your upgrade.
If you have more than one subscriber, you can upgrade them all at the same time. Main thing to remember here is to have your publisher upgraded, then rebooted to stability. After that, you can do your subscribers simulteanously and reboot them one by one.
You might run into the issue where the CUCM machines do not recognize your DVD media upgrade, you can either do SFTP or CLI to get the file over to the CUCM boxes.
Here is a good resource for the CLI upgrade method.