Dated but interesting paper from Audio Engineering Society Convention 2004 regarding An Internet Protocol (IP) Sound System. PP#5-6 [Microsoft] discusses NTP use and possible modifications they would have made to make it more accurate. [pdf attachement]
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Richard B. Gilbert Sent: Monday, April 03, 2006 4:37 AM To: [email protected] Subject: [ntp:questions] Re: NTP client on Windows platform provides less accurate results then on the UNIX or Linux. Why? Ry wrote: > On 4/2/06, Danny Mayer <[EMAIL PROTECTED]> wrote: > >>That should have no more affect on NTP than anything else running on >>the box. We have seen no such affects. If you want to report a problem >>then you need to send much more detail. > > > I'm not reporting a specific issue, I'm just pointing out potential > problem areas for the original poster to look at. Additional, > systemic, asymmetric latency on the Windows machines would certainly <snip> > > On both of my stratum-2 boxes on Windows 2003sp1, they converge to > withing a half-dozen milliseconds in about 8 hours. But after running > for several days, they seem to converge to within ~1 ms offset. I > don't know why that is, but NTP certainly does seem to get better on > my Windows machines over longer periods of time. When I frequently > restart a machine, I never get much better than 10ms accuracy. I don't > know why that is, other than NTP isn't disciplining the clock during > the actual shutdown and restart. > > Of course drift would only be about 2 ms per minute of NTPd downtime > on a 30ppm machine. But it seems to me after NTPd is down it over > corrects a bit with the drift calculation and I get a few swings > before it settles in after 8 or so hours. I posted a chart of this > "restart over correction" on an XP box at: <snip> I have noticed similar overcorrections when starting my Sun Ultra 10/Solaris 8/ntpd 4.2.0. This machine is equipped with a Motorola Oncore reference clock. It started up about ten milliseconds off, started correcting and overshot by nearly ten milliseconds. It then overshot in the other direction. I didn't time the process but it took at least thirty minutes to settle down. I think I could have figured it out faster with pencil and paper! _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
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