[ntp:questions] Poll timing

Steve Kostecke kostecke at ntp.org
Thu Aug 16 12:21:28 UTC 2007

On 2007-08-16, Jussi Kauppinen <jtkauppi at cc.hut.fi> wrote:

> Paul.Croome at softwareag.com wrote:
>> Why should the exact instant when NTP polls be important? It doesn't
>> matter whether the polling interval is 64 seconds or 64.1 seconds or
>> whatever.
> I'm developing a system that utilize NTP. Unfortunately, the details of 
> the system are confidential. For this system to work properly, it is 
> essential that polling phase inside a second is approximately constant 
> related to the clock of the client,

The exact poll timing is irrelevant as far as NTP is concerned.

The Unicast (i.e. client/server) polling scheme time-stamps the packet
when it is sent from the "client", at the "server", and again when it
arrives back at the "client". These three time stamps are collected at
each poll interval from each time source. The NTP algorithms use these
time-stamps to, over time, determine what the correct time is.

Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/

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