[ntp:questions] Number of Stratum 1 & Stratum 2 Peers

Harlan Stenn stenn at ntp.org
Thu Dec 18 00:25:32 UTC 2014


Martin Burnicki writes:
> Harlan Stenn wrote:
> > Martin Burnicki writes:
> >> Rob wrote:
> >>> Unfortunately, the same mechanism isn't used for leap seconds.
> >>> There would be no problem at all when the system time ticked in TAI
> >>> and the addition of the leap seconds is done via some rule table similar
> >>> to the local time rules.  ntpd would not even be involved in the problem.
> >>
> >> Also agreed. However, actually ntpd expects UTC, not TAI.
> >
> > One of the things I'm thinking about for NTP5 is systems that choose to
> > run in TAI and not UTC.  This is a natural tie-in with NTF's General
> > Timestamp API, as we need to know what timescale the remote system is
> > using.
> 
> Of course. However, you would anyway need the current rules or 
> algorithms required to do the conversion.
> 
> > This woud also handle the case of maintaining sync with a system that
> > chooses to implement Google's leap smear,
> 
> Do you know the *exact* algorithm how Google smears a leap second? If 
> you don't know it there will be differences in the time computed by 
> standard ntpd v5 and Google's. ;-)

I know what they've published.

If we assign unique "leap method numbers" and folks actually use these
properly, at worst we would say "Don't sync with Google Leap Smear
machines on the day a leap second is being processed".

If a system is using an older NTP it will ID as v4, and any ntp5
instances will be able to "know" to be careful.
-- 
Harlan Stenn <stenn at ntp.org>
http://networktimefoundation.org - be a member!


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