[time-nuts] Tracking NTP displacement and correlation betweentwo clients.

Bob Bownes bownes at gmail.com
Fri Oct 5 00:42:42 EDT 2012


David,

The problem is that they start in sync and over the course of a day drift that far apart despite having NTP running. We're not sure why NTP isn't correcting it along the way. Though at this point, we are looking at a firmware bug.

Thanks!
Bob

On Oct 5, 2012, at 12:30 AM, "David J Taylor" <david-taylor at blueyonder.co.uk> wrote:

> The problem stems from one of the two (identical) machines drifting off by
> 60-70 seconds per day. So a few ms here and there are ok.
> []
> Bob
> ==================================
> 
> Bob,
> 
> NTP is normally limited to a +/- 500 parts per million correction - 43 seconds per day.  You may be operating outside the range NTP is expecting to handle.  If the clock offset is a stable value of 60-70 seconds per day you can bias NTP to correct within +/- 500 ppm of that drift.
> 
> Cheers,
> David
> -- 
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-taylor at blueyonder.co.uk 
> 
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