[ntp:questions] Frequency adjustments in a local network

William Unruh unruh at invalid.ca
Thu Apr 3 15:34:59 UTC 2014


On 2014-04-02, Maximilian Brehm <maximilian.brehm at tu-ilmenau.de> wrote:
>
>
> Hey NTP community, 
>
> I need to synchronize only the frequency of a
> destination systems based on the frequency of a reference system in the
> same network. This is because the reference system does not supply
> timestamps and they are not important for the destination system. So, I
> would say I need (a) only frequency and no clock adjustments for the
> destination system and (b) a method to synchronize clocks via a local
> network. 

The latter behaves just as does any other server. The former is NOT part of
ntpd. ntpd adjusts the frequency based on what the offset in time is. If
the time offset is positive (system clock ahead of remote clock) the
frequency is decreased, etc.

It is unclear to me how you would determine that the frequency of one
system is different from that of the other without using time stamps. 
Under chrony, the frequency and the offset are calculated separately
(from a series of timestamps.) and the chrony could be rewritten to
ignore the offset. But it would require a rewrite, since the whole basis
of any program using ntp protocol is precisely to bring times, not
frequencies, together.
>
> Are there ways to achieve this using NTP that are implemented
> or may be implemented? If yes, can you recommend me starting points for
> either way? 
>
> Thanks 
>
> Maximilian Brehm



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