[ntp:questions] Re: All my servers rejected

David Woolley david at djwhome.demon.co.uk
Wed Jan 7 21:00:10 UTC 2004


In article <cMZKb.47412$Dm.45292 at edtnps89>,
"David Moerman <david.(dot)m@(at)advmeas.(dot)com>" <> (munged) wrote:

> I've got a situation where I'm trying to synchronize through a modem
> connection (115200 bps through a satellite).  Ping delays are between 2 to
> 3.5 seconds, and jitter is often above 1 second.  I've tried between 3 and 5

This significantly exceeds the maximum permitted root delay.  No servers
will be acceptable over such a link.  You need to get round trip
times significantly under 2 seconds (and repeatable to under 200ms).
I suppose you could change this figure, but I suspect you will violate
various stability assumptions, not that you can use the NTP protocol
properly over a low duty cycle connection.

You need a radio clock or to use GPS satellite data directly.

Over your satellite link, I think that only a very minimal SNTP
implementation could be justified as the data quality wouldn't support
anything better.



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