[ntp:questions] Re: Best way to harness multiple stratum 1 servers

Ronan Flood ronan at noc.ulcc.ac.uk
Tue Apr 4 17:55:17 UTC 2006

jra at febo.com (John Ackermann N8UR) wrote:

> Old HP 5061As with the digital clock option; they provide a 1pps output 
> to use with the ATOM driver.

Ta.  I see Symmetricom are selling the 5071 now, I shall have to
investigate their range (for our own purposes, see earlier posts).

> I guess my question may go to the fundamentals of ntp:  can an NTP 
> server ever do better than any of the individual servers it sees?  In 
> other words, does the algorithm blend the offset/jitter/delay 
> information it has to generate a concept of time based on not just one, 
> but the ensemble (or at least the survivors of the sanity checks), of 
> the available servers?  If so, how best to configure that?

Left to itself ntpd is supposed to do that, and there is anti-hopping
code in newer versions -- see clock_select() in ntp_proto.c and the
description of mitigation in


                      Ronan Flood <R.Flood at noc.ulcc.ac.uk>
                        working for but not speaking for
             Network Services, University of London Computer Centre
     (which means: don't bother ULCC if I've said something you don't like)

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