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Changing NTP server stratum for CUCM 10.x

Kevin SAS

Hello guys,

During a migration for our CUCM (9 nodes) + 2 IMP, we encountered some failures in the process with NTP check step.

Our NTP server was stratum 6 instead of recommended stratum 1 to 3 for the nodes.

I want to change the stratum, but, If I change my ntp server, I need to reboot all the nodes according to the cisco documentation

-> don´t want that

Second plan : I can change the actual stratum for the actual NTP server (2 cisco GW) in changing the NTP server by an external.

Question : does I need to reboot if my NTP server change it stratum ?

Any advices ?

Thanks in advance

1 Accepted Solution

Accepted Solutions

Hi Kevin,

You are right , the documentation does point to a cluster reboot after NTP change. So i would recommend doing it in a maintenance window.


View solution in original post

7 Replies 7

Manish Gogna
Cisco Employee
Cisco Employee

CUCM server restart is not needed when you add / delete or modify NTP server information. Just update the NTP information and do a "utils ntp restart" and it should be good enough to synsc cucm with correct NTP. We recommend that the NTP for the publisher is set to stratum 1, 2, or 3, and that you use only a Linux or IOS NTP source. Windows Time Services as an NTP server is not recommended or supported.


Thanks for your response.

However, according this OS guide, it is mandatory to reboot all the nodes

But if you confirm me, it will be good if I change the stratum on my current NTP server, I will do that

Hi Kevin,

You are right , the documentation does point to a cluster reboot after NTP change. So i would recommend doing it in a maintenance window.


Thanks for your assistance

[+5] to Manish.

I faced this issue where in I had to delete NTP server and then, add new NTP server in CUCM.

SO, you need to have at least one NTP server defined else u won't be able to delete the existing one.

Also, the new NTP server should be reachable. If not, u won't be able to add that.

Lastly, no reboot of CUCM is required when NTP is changed.



Hi Aman,

To be honest even i don't remember rebooting cluster after changing NTP and i have done it N number of times. However, i am a bit surprised by this documentation, maybe if Kevin can open a TAC case to get it confirmed and possibly get a documentation defect opened if it actually turns out to be incorrect. At least it will get the things clarified. My suggestion would be to try the NTP change and observe the stratum and database replication on cucm cluster for a couple of hours. If all stays well there should be no need for reboot.


I will keep you updated, I asked to change the NTP server stratum for next week in NBH.

I will then monitor the ntp status, if all is good, fine.

if not, I will restart the ntp service and worst case restart the node.


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