[ntp:questions] What level of timesynch error is typical on Win XP?

Joseph Gwinn joegwinn at comcast.net
Fri Oct 22 11:37:51 UTC 2010


In article <i9r6cb$627$1 at news.eternal-september.org>,
 "David J Taylor" <david-taylor at blueyonder.co.uk.invalid> wrote:

> "Joseph Gwinn" <joegwinn at comcast.net> wrote in message 
> news:joegwinn-EE48FD.22434621102010 at news.giganews.com...
> > In article <i9pkvb$dc6$1 at news.eternal-september.org>,
> > "David J Taylor" <david-taylor at blueyonder.co.uk.invalid> wrote:
> []
> >> You might consider providing a local, more precise NTP server with
> >> something like a small, fan-less Intel Atom system running FreeBSD and
> >> synched across the network to your GPS time server.  You might be able 
> >> to
> >> keep a small box like that in a more temperature controlled 
> >> environment,
> >> but even without it might provide a way of smoothing out any jitter due 
> >> to
> >> your remote connection to the GPS server.
> >
> > I'm not convinced that this would help.  NTP reports a round trip time
> > of slightly more than 2 mS, which is very close to the two milliseconds
> > that ping sees, so it seems unlikely that the time server or intervening
> > network is the root cause.
> []
> > Joe Gwinn
> 
> No, I wasn't convinced either - hence it was just a suggestion.  On the 
> systems here, though, the NTP delay shows around 0.25-0.75 msec to the LAN 
> servers.

I must say that I don't know why ping sees 2 milliseconds, which did 
seem high, but I also don't know the physical location of the 
timeserver, or how many hops (and firewalls) it takes to get there.  
I'll have to explore it with traceroute.

But the 2 ms RT time explains only a millisecond or so of timesync 
error, leaving much error to be explained.  Research continues.


Joe Gwinn




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