[ntp:questions] Slow convergence of NTP with GPS/PPS

Unruh unruh-spam at physics.ubc.ca
Fri Oct 24 17:27:47 UTC 2008


hal-usenet at ip-64-139-1-69.sjc.megapath.net (Hal Murray) writes:


>>It is more like 20m. And even for 2000km (Vancouver to Regina) on the
>>public CanadaNet network it is only 40ms.

>The time-of-flight (speed of light) delay doesn't matter (much).
>It's mostly a constant.  (Routing shifts on long paths introduce
>shifts.)

>The problem is queueing delays.  They aren't stable.

Agreed. Which is also why I find it amazing that on my gps controlled
server, with a Regina level 1 backup, the regina offset is less than 1ms
even though the round trip time is 40-50 ms. Ie, assymmetric router delays
do NOT appear to be a problem.
Just one data point however.. 





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