Question on setting up NTP on Cisco Voice Gateway for CUCM 9.1

[Fahim Sha]

Hi Guys,

I do have question on setting up NTP on Cisco Voice Gateway (3825 Series Router).

What we have been trying to do is as follows. CUCM 9.1 will be pointed to Cisco 3825 Router for NTP. And the Cisco 3825 Router will sync with a public IP address (from internet) for NTP.

Inorder to achieve this, the following commands were entered in Cisco 3825 Router

ntp master

ntp server <ip address for NTP from internet>

And as mentioned above, ntp for CUCM 9.1 will be Cisco 3825 Router.

Now, the issue that I come across is that, whenever the Cisco 3825 Router is in sync with Internet NTP IP address, CUCM 9.1 will be unsynchronised with Cisco 3825 Router (but still accessible in CUCM OS Administration --> Settings --> NTP Server).

And, whenever Cisco 3825 is not in sync with Internet NTP IP address (in sync with local time of Router), CUCM 9.1 will be in sync with Cisco 3825 Router.

I couldn't find CUCM 9.1 in sync with Cisco 3825 Router, when Cisco 3825 Router isin sync with Internet NTP IP address.

Is this behaviour normal, or is this any kind of bug / issue?

We have scheduled to upgrade the IOS of Cisco 3825 Router this weekend, to see if have any changes.

I will keep you posted. At the same time, any suggestions would be appreciated.

Am I missing out something ??

With Kind Regards,

Fahim Sha.

[James Hawkins]

Hi,

Do you know what stratum number your gateway is advertising itself as to CUCM?

utils ntp status on the cucm console should tell you this

I think that CUCM can only sync with NTP servers of stratum 10 or less.

If you are seeing a high stratum advertised from the gateway try setting it lower using the optional argument on the ntp master ios command

It can take CUCM some time to sync with an NTP server especially if the initial time on the server is a long way off what is being received from NTP.