[ntp:questions] Packet timestamps when using Windows-7/Vista

Martin Burnicki martin.burnicki at meinberg.de
Mon Dec 14 11:07:50 UTC 2009


unruh wrote:
> And given these results would the advice given by some in this list
> to go ahead and use Windows as a time server still stand?
> 
> (Of course it depends on the accuracy required. For 1 sec accuracy, it
> looks like it should be fine.)

Yes, that's exactly the point, as also mentioned by David J. Taylor.

You *can* run ntpd on Windows machines and use them as a time server, if the
resulting accuracy is sufficient, e.g. if the clients are also Windows
workstations which suffer under the same timelkeeping limitations as the
server.

Undoubtfully there are better ways to set up a NTP server using a Unix-like
OS in a mixed environment. 

BTW, there is currently a bug in the NTP version shipped with openSUSE 11.2
which lets the measured time differences reported in the loopstats files
bounce from -0.5 ms to +0.5 ms, i.e. the granularity is degraded to 1ms.

This is reported in:
https://bugzilla.novell.com/show_bug.cgi?id=557716

Looks like this is an openSUSE specific problem to work around a problem
reported in NTP's bug #1219:
https://support.ntp.org/bugs/show_bug.cgi?id=1219

The good news here is that this can be fixed since the code which does the
timekeeping is known (both NTP and the kernel), whereas under Windows NTP
needs to workaround limitations of the Windows kernel the code of which is
not known, so the workarounds can only be based on assumptions how the
kernel works.

Martin
-- 
Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont
Germany




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