[ntp:questions] ntpd stuck at default minpoll on stratum one

Per Hedeland per at hedeland.org
Sat Oct 6 18:50:54 UTC 2007

In article <hoikt4-f6p.ln1 at osl016lin.hda.hydro.com> Terje Mathisen
<terje.mathisen at hda.hydro.com> writes:
>Dennis Hilberg, Jr. wrote:
>> Hi,
>> I have a stratum one server running ntpd 4.2.4p3 at 1.1502 with a Garmin 
>> GPS 18 LVC as a refclock.  I use the shmpps driver from 
>> http://time.qnan.org/ . Since this driver only provides the PPS signal, 
>> I need to have a few other servers defined in my ntp.conf so that my 
>> ntpd knows what time it is.
>> Here's my concern: the poll interval on those servers is always stuck at 
>> the default minpoll (64sec), even though I have not specified so.  I 
>> would rather not poll those servers at such a rapid rate, but ntpd seems 
>> to be doing this on its own, as far as I know.
>I think this is a known problem/bug/feature: The prefer peer responsible 
>for naming the PPS ticks is clamped at minpoll. In fact, if you adjust 
>minpoll to 4 (i.e. 16 seconds), which can be a good idea for a GPS-class 
>PPS signal, then you'll also lock your prefer peer at the same rate.

AFAIK it's not limited to the prefer peer - note that Dennis' ntp.conf
didn't have 'prefer' on *any* of the remote servers, I believe having
one used to be a requirement for a PPS-only clock to work, but
apparently that has changed. I.e. if you have a reference clock, *all*
remote servers will be clamped at minpoll for the reference clock.

--Per Hedeland
per at hedeland.org

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