On 2017-01-22 23:46, suhas manjunath wrote:
>> Sources marked true are passed by the select process;
>> sources marked prefer may be discarded by the select process;
>> sources marked true or prefer may be discarded by the cluster process;
>> sources marked prefer reaching the combine process will be selected
>> as the system source and their offset and jitter used as the system
>> values used to discipline the system clock.
> But the man page of ntp.conf says using true option it will always
> survive the selection and clustering algorithms.
> "true
> Force the association to assume truechimer status; that is, always
> survive the selection and clustering algorithms. This option can be
> used with any association, but is most useful for reference clocks
> with large jitter on the serial port and precision pulse-per-second
> (PPS) signals. Caution: this option defeats the algorithms designed
> to cast out falsetickers and can allow these sources to set the
> system clock. This option is valid only with the *server* and *peer*
> commands."
> So if i use true and prefer option together it has to pass cluster
> process also and hence it has to be taken as preferred server. but in
> our case it is not taking as preferred server.
Look at the html pages for select, cluster, and prefer/combine:
https://www.eecis.udel.edu/~mills/ntp/html/select.html
https://www.eecis.udel.edu/~mills/ntp/html/cluster.html
https://www.eecis.udel.edu/~mills/ntp/html/prefer.html
which say what I said above: I tend to believe the algorithms pages
over the conf man or html pages.
I also suspect that a server can either be marked true or prefer but
perhaps not both.
Only the sources can really tell us which of the possible alternatives
for these options are correct:
https://github.com/ntp-project/ntp
--
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
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