On Jul 20, 10:36 pm, "David J Taylor" <david-tay...@blueyonder.not- this-part.nor-this.co.uk.invalid> wrote: > paul wrote: > > Hi All, I'm new to NTP, glad to meet you here. > > > I did some experiments to test NTP performance on WINNT. In an > > isolated network, two machines are inter connnected with a switcher. > > Machine A is configure as a stratum 12 NTP server, using lcl as > > reference clock; machine B is sychronized to machine A. Then, 'ntpq - > > p' is performed on machine B every 16 seconds. The output of ntpq is > > cooked by a python script and offset field is recorded to log file. > > After about 2 hours, I check the log file and found the offset value > > is 4 ~ 8 ms. Is this normal? I mean if things are properly done, how > > small the offset I can expect? Thanks. > > > The OS is Windows XP Pro SP3 and NTP software is 4.2.4-p7 from > > mainberg. > > Paul, > > For comparison, I have the performance of a mixture of Windows systems > running a mixture of NTP versions plotter here: > > http://www.satsignal.eu/mrtg/daily_ntp.html > > The Windows XP system synced to a local stratum-1 clock is Narvik, showing > an offset of within 1.5ms, but that is with a poll interval clamped to > 64s. The best is the system Feenix with a local GPS serial and PPS > reference clock (but no temperature control) where the offset is within > about 0.2ms, and the worst the Windows Vista system Gemini which has a > DVB/USB data reception system capturing about 20GB/day, but clobbering the > offset with transient peaks of at least 50ms. > > "How long is a piece of string...." comes to mind! > > Cheers, > David
Thank you, David. In my situation, no GPS is availiable. So can I expect better performance when GPS is used as reference clock, or when a stratum-1 NTP server is added to the network? And, I noticed the offset for Narvik is more stable than that for Hydra, is it due the PPS feeded to Narvik? But Bacchus is doing good too without PPS, Why? _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
