Upgrade CUCM 11.0 to 11.5

[bkhanal1971]

I am planning to upgrade my 11.0 CUCM cluster to 11.5 soon. I went through the link https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/upgrade/11_5_1/cucm_b_upgrade-guide-cucm-115/cucm_b_upgrade-guide-cucm-115_chapter_010010.html to get understanding on various upgrade scenarios. In my case, I would need to be able to perform the upgrade with least impact on the phone service as ours is 24x7 environment. The sequence of operation mentioned in Table 4 states that I perform upgrade on all subscriber nodes in parallel after upgrading publisher. Here I am unclear about what happens to the phones when I am upgrading all subscribers in parallel? Do they stay registered and functional? If so, then there will not be much downtime for the phone service other than the time it takes for the phones to fall back to secondary subscriber as primary subscriber is going through switch version and vice versa. Is this true?

Just want to make sure I get it right before I begin the upgrade.

Thanks for your help.

Regards, Khanal

Thank

[j.huizinga]

Upgrade from 11.0 to 11.5 is a minor upgrade, so no issues with licenses

You first must upgrade the publisher, when this is successful you can start with the subscribers. When all machines have upgraded correctly you do switch-version on Pub and when this server is up and running you do the subs one by one. When a phone switches from an 11.0 to 11.5 server it might do a firmware upgrade, and depending on the phone, the phone can be unusable for several minutes

Also 11.5 removed some support for older Cisco phones, check if you have some of them

JH

[bkhanal1971]

Thanks for the response. So, while I am upgrading the subscribers, phones continue to work correct?

[Gregory Brunn]

While you are installing the upgrade into the inactive partition services are not impacted. Services will only be impacted when you are switching version.

If you want to mimizie your upgrade impact, I would install the exact version of phone firmware needed prior to the upgrade. You can find the phone firmware in the CUCM release notes.  Also you will want to switch version on your subscribers based on your CUCM groups.  We will keep it simple. If you have have 1 CUCM group that has Sub1 and then Sub2 You would switch version on sub 2 then sub 1 so phones stay up until you switch version on Sub1.  Note the more CUCM groups the harder this becomes to plan. I always just set up a maintenance window that will cover the entire time it would take it do the switch version on my subscriber nodes.