[ntp:questions] Bug 2341 - ntpd fails to keep up with clock drift at poll>7

David Taylor david-taylor at blueyonder.co.uk.invalid
Tue Dec 3 08:59:15 UTC 2013


On 03/12/2013 00:34, Brian Inglis wrote:
[]
> BTDT, but we all still need decent network servers as check and backup
> in case
> there are ref clock issues - we don't all have an in house NTP Server
> farm! ;^>

Yes, having good Internet servers as a backup or check is desirable, if 
not mandatory.  I recall that in the early days with Windows before all 
the interpolation and other improvements were added to NTP I was 
plotting offsets on a +/- 100 ms scale - that's how bad it was.

If someone can only use Internet servers, it's better to have a small 
(e.g. Raspberry Pi) Linux or FreeBSD local server, or perhaps a Windows 
8.1 box, syncing to the Internet, and to which the Windows PCs are 
synced with a small poll interval (say 32 seconds).  For the RPi alone:

   http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#results

I've not tried Windows directly taking its time from the Internet for 
quite a while except on holiday, when I saw offsets in the 10 -25 
millisecond range, and averaged jitter up to 30 milliseconds.  This 
through whatever Wi-Fi connections were available.  The offset did 
converge, though.  Poll interval started at 64, but never got higher 
than 256 seconds over a couple of hours of use.

Hope that helps.
-- 
Cheers,
David
Web: http://www.satsignal.eu



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