[ntp:questions] systems won't synchronize no matter what

Dave Hart davehart at gmail.com
Thu Oct 28 11:52:10 UTC 2010


On Thu, Oct 28, 2010 at 11:07 UTC, Parvin, Richard
<richard.parvin at hp.com> wrote:
> I've noticed that a lot of people use iburst on thier server lines.  I'm wondering why.

http://www.eecis.udel.edu/~mills/ntp/html/confopt.html#server

As explained on the "Poll Program" page that links to, iburst reduces
the time to initial sync.  ntpd requires three exchanges with a source
to partially fill the 8-sample clock filter register before it will
draw any conclusions.  Without iburst, that means a few minutes at the
default initial poll interval of 64s.  iburst accelerates the process
by sending a series of six requests 2 seconds apart when starting up,
and also after a server has become unreachable.  The first packet must
elicit a response or the rest are not sent.

The visible result when using iburst on all your server lines is it
takes a few seconds instead of a few minutes for ntpd to take the
wheel (and possibly step the clock, if out more than 128ms by
default).

Cheers,
Dave Hart



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