CUCM 6.1 SCCP NTP - Pub linked to NTP, but will it update for DST changes?

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Jul 20th, 2009
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Hi all,

I have an NTP source added in OS Admin to reference one of our Stratum level 2 devices (a Domain Controller that automatically updates for BST changes etc)

Quick question - although my NTP source for the SCCP phones we use is setup, my "Date/Time group" in the Admin GUI is setup as "GMT Standard/Daylight Time GMT"

Does this infer that CallManager will remain "dumb" to any daylight savinggs time dates, and will ONLY pull correct time from the NTP source with which the Publisher is linked?

Im a little worried that the recent March 2009 DST/BST debacle :o) where IP Phones didn't adjust might impact us again, even though I have a valid NTP source set...?

Im running CUCM 6.1(2) and currently the times are correct after setting the NTP source, restarting my Pub and Subs, then resetting all the devices in my Time/Date Group. Im not certain this will remain the case when BST ends later this year :o)

Thoughts appreciated.


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James Hawkins Mon, 07/20/2009 - 06:49
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Hi Andy,

My understanding of NTP is that it just supplies UTC time and it is the receiving systems responsibility to apply any offset (from UTC) and to implement things like Daylight Saving.

If your NTP server suddenly changes the time it is advertising by one hour the NTP client will not accept the update immediately and will probably mark the servers as "insane" -i.e. not believable.

You would be fair better off selecting the GMT/BST timezone within CUCM and the timechange should be totally seamless.

andy_vvc2 Tue, 07/21/2009 - 01:35
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Cheers Jamesha. I was hoping that i wouldn't have to update the NTP source and that CUCM would do all the changes :o) I guess i just hope that the recent DST issues were US related only and that GMT/BST timezone settings will work fine.

James Hawkins Tue, 07/21/2009 - 08:18
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Hi Andy,

We have lots of UK based customers with CUCM6/7 and daylight saving works ok for them. I think the problems in the US were caused because the dates on which the daylight savings adjustments changed.


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