[ntp:questions] Re: ntpd Not Converging
David J Taylor
david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk.invalid
Fri Nov 4 14:44:57 UTC 2005
David T. Ashley wrote:
> But the replies did not zero in on the key question. It is a control
> law question. When ntpd starts and the server time is off of the
> true time by an offset (say, 2 seconds), what "control law" does it
> apply to reconverge the server's time and the true time?
A simple answer would be:
- if the clock is off by a large amount, it is first stepped
- a damped control loop is then used to keep the offset approaching zero
- recognising that there is a fixed rate offset which is the value stored
in the drift file
I don't understand why you delete the drift file, as that file is supposed
to speed the convergence process. There is a limit of 500 ppm in the
clock error beyond which NTP will not converge.
Now, please note that this is my simple and rough understanding - there
are many far more expert than me here, so if my description is incorrect I
hope they will correct me. You should also read David Mills'
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