[ntp:questions] Getting NTP to correct only the clock skew

Maarten Wiltink maarten at kittensandcats.net
Mon Apr 2 13:36:55 UTC 2007


"Spoon" <devnull at localhost.com> wrote in message
news:4610e30a$0$12301$426a74cc at news.free.fr...
[...]
> B is supposed to re-send the packets it receives at the rate they
> were originally sent by A.
[...]
> If the clocks on A and B do not tick at the same rate, the buffer
> used by B will either overflow or underflow.
>
> This is why I need A's clock and B's clock to tick at the same rate.
>
> But it is not important to me that A and B's clock give the same
> absolute time. ...

But nothing will break if they do, either. Right? The simplest solution
would be to have both synchronised to UTC, or either one to the other,
and accept that they will keep better time or at least closer time.
>From the sound of it, you do not care about what time A keeps _at all_,
so if you simply slave it to B, your problem goes away.

The fact that you are concerned with reproducing timing but not with
good time is, frankly, suspect and leads me to propose a different
'solution': could you monitor the buffer length and adjust frequency
on system B from that? If it's slowly draining, slow down B a little;
if it's growing, speed it up ever so slightly. Just like NTP does,
really.

Groetjes,
Maarten Wiltink





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