Tim,
A good deal of quality design time went into the statistical analysis of
errors and the manner in which statistics are presented to the
application, in this case via ntp_gettime(). You don't want to know
anything other than the carefully maintained maximum error and estimated
error statistics. Neither the stratum of the server nor the poll
interval nor the precision nor any other statistic is necessary to
evaluate the quality of time. The maximum error and estimated error
already take those factors into account. You really don't want to second
guess what the server is doing, just that it and the local client are
providing dependable statistics.
As I said in my last, your clock is Big Ben and NTP is manipulating the
number of farthings, h'apennies, pence, shillings, pounds and guineas on
the pendulum. [Gawd, after 33 years since decimalization, I'm not sure I
remember how to spell all that coinage.]
Dave
Tim wrote:
On Wed, 05 Oct 2005 18:34:08 +0000, Brian T. Brunner sent:
missing from the ntpd design(?): some system-readable TimeIsGood flag set
by ntpd for applications to use where they must have trustable time. alt:
TimeStateIs flag with values of LOST (no net, no idea what time it is),
SEEKING (found a source, getting time), and SYNC (time is good) alt:
SEEKING_n for n ranging 1 to the "minimum acceptable set size" for your
site; SYNC means the highest minimum has been met. This allows different
applications to decide when is the time sufficiently good for that
application.
Are you saying that the stratum information can't provide you with
adequate information about how much faith to put in your time, or that the
output from ntpstat (three different example results below) isn't machine
parseable in some useful way?
synchronised to local net at stratum 8
time correct to within 12 ms
polling server every 64 s
unsynchronised
time server re-starting
polling server every 64 s
synchronised to NTP server (83.137.103.134) at stratum 3
time correct to within 264 ms
polling server every 64 s
_______________________________________________
questions mailing list
[email protected]
https://lists.ntp.isc.org/mailman/listinfo/questions
