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UCM - Migrating from IP address to FQDN

Simon Battye
Level 2
Level 2

Hi,

I am in the process of planning an upgrade from UCM/UCXN v9.1 to v11 with an end goal of integrating everything with IMP/Expressways for MRA/Expressways for Jabber Guest/ Conductor and vTPS.

With this in mind i will need to move from IP address to FQDN on the UCM/UCXN servers in order to cover off certificate dependencies and allow everything to integrate seamlessly.

So at the moment UCM is configured with:

  • Hostname configured in OS Admin
  • IP Address configured in System -> Server
  • No DNS Servers and no DNS Domain configured

I understand the dependencies of ensuring all phones and gateways should have DNS servers configured but i am led to believe that it is possible that post-changing to FQDN could cause the phones not to register due to the ITL certificate.

Has anyone come across this before or got a workaround to prevent the phone certificate issues?

Thanks, Simon

1 Accepted Solution

Accepted Solutions

I would recommend doing them as two completely separate changes. Changing the hostname has many of the same implications as adding a domain to the CUCM (host file changes, regenerate all certs at once, need to reboot servers, etc...). I personally would do the hostname change first, then give it at least another week before doing the domain addition so I can identify any issues. Maybe someone else out there has a different take on it though and a good process to follow that ensures you won't break anything serious.

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/install/10_0_1/ipchange/CUCM_BK_C3782AAB_00_change-ipaddress-hostname-100/CUCM_BK_C3782AAB_00_change-ipaddress-hostname-100_chapter_011.html

View solution in original post

7 Replies 7

Jaime Valencia
Cisco Employee
Cisco Employee

So long you do not change the settings in all servers at the same time, or one right after the other, it will work fine, read here

http://www.cisco.com/c/en/us/support/docs/voice-unified-communications/unified-communications-manager-callmanager/116232-technote-sbd-00.html

HTH

java

if this helps, please rate

Jamie,

Thanks for this.

So as long as i make the changes on the publisher first and only proceed with the subscriber once the Publisher has rebooted and is back active on the network - i should be OK.

There is no CTL used on this cluster.

Jaime is saying to not do all servers at once, or even to closely to each other. If you do one node, wait for the server to come back online, then wait for the phones to register again, then move on to the next node, so on and so forth, you should be fine (assuming there are not ITL issues currently). Here is a video I made about how to do it soup to nuts.

https://supportforums.cisco.com/document/12759291/how-enable-dns-cucm-versions-9-through-11-after-installation

please let me know if you have any questions after watching the video and I should be able to clear up any confusion.

The video is really useful, thanks for that! I just wanted to be 100% clear on the procedure to minimise any risk.

One last question, if i am changing the hostname as well as adding DNS servers and a DNS Domain, should i ensure that the Hostname is changed before adding the DNS? Are there any implications i should be aware of changing the hostname or should i be OK as long is a work on one node at a time and give plenty of time before moving onto the next.

Thanks, Simon

I would recommend doing them as two completely separate changes. Changing the hostname has many of the same implications as adding a domain to the CUCM (host file changes, regenerate all certs at once, need to reboot servers, etc...). I personally would do the hostname change first, then give it at least another week before doing the domain addition so I can identify any issues. Maybe someone else out there has a different take on it though and a good process to follow that ensures you won't break anything serious.

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/install/10_0_1/ipchange/CUCM_BK_C3782AAB_00_change-ipaddress-hostname-100/CUCM_BK_C3782AAB_00_change-ipaddress-hostname-100_chapter_011.html

Please rate helpful content (i.e. videos, documents, comments) and please select the correct answer(s) if any comment(s) answer your question.

Otherwise it remains in the list of unanswered questions on the support forum.

Ayodeji Okanlawon
VIP Alumni
VIP Alumni

Simon,

I recently did this and due to a lack of proper documentation I wrote a guide on how to do this and the pitfalls to avoid.

Please refer to the guide here..

https://supportforums.cisco.com/document/12948656/changing-cucm-host-names-ip-address-fqdn

NB: One major difference is that in my case, the servers were already defined using FQDN in the OS platform, I was only changing the system server name from IP to FQDN. The greater implication of this is that in my case my certs were not regenerated since I wasn't changing my domain name etc..

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