[ntp:questions] Ref clocks and polling intervals

Chris Hastie chris at loopy.oak-wood.co.uk
Wed Nov 24 09:09:18 UTC 2004

About a year ago I raised an issue I was having whereby as soon as I
connected a ref clock the poll interval for all other sources dropped to
64s and stayed there.

A message from David Mills that I missed was recently brought to my
attention and as a result I upgraded to a dev version announcing itself
as 4.2.0 at 1.1179-r Wed Nov 17 16:04:21 GMT 2004 (1).

This has led to poll intervals rapidly reaching 1024s. But as David
points out in the message, it stiffens the PLL frequency and
consequently I'm seeing a marked diurnal oscillation of offset - the
machine is no where near air conditioned, in fact it's in a room that
the woodburner's chimney goes up through :( See <http://ntp.raggedstaff.

10 or 11 hours ago I set maxpoll to 8 on the reference clock in an
attempt to find a compromise. It's early, but it looks as if this may
have calmed down the daily swings a bit. But of course it's also
increased the frequency of polling to other sources.

Can anyone give me some hints as to what effects the following might

1)  Reduce maxpoll for the reference clock to 6, but explicitly set it
    to 10 for all other sources.

2)  Reduce maxpoll for the reference clock to 6 but use a tinker maxpoll
    10 command

What I'm trying to achieve is a reduction in the daily swings whilst
still being a better neighbour than with a 64s poll interval to

Chris Hastie

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