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

Harlan Stenn stenn at ntp.org
Tue Dec 16 22:55:46 UTC 2014

Martin Burnicki writes:
> Harlan Stenn wrote:
> > An alternative is that we get enough support to advance NTF's General
> > Timestamp API, and then we can run systems on either TAI or UTC and
> > these conversions will happen automatically.
> >
> > Since timescale files in the GTSAPI are "versioned", one could still use
> > an obsolete leapsecond file, and while those UTC timestamps would be
> > "wrong" if a new leapsecond was added, these timestamps would be
> > correctable when a new version of the UTC timescale file was available.
> Hm, that may not really help if the API returns a wrong UTC time stamp 
> which is then used to set the system time wrong.

Anything on the box that uses UTC in this situation will be using an
outdated UTC timescale, and when any newer versions are made available
the library API will handle the conversion.

Think of the case where you want to set an event for a future time - if
you want to tag something with an absolute time of 10am UTC a year in the
future, there's no way to know if there will be a leap second in there
or not.  So as we get closer to the actual date, if the UTC timescale
gets updated the absolute UTC timestamp will be properly adjusted as
soon as we know.

Similar things happen if one is using an IERS timescale, which gets a
new version every week.

> The tzdist protocol could also be helpful here to provide the 
> information required to do the conversion correctly. An expiration date 
> could be used for versioning.

I'm sure that will play a factor in this, and the "timescale version"
stuff will be covering a number of different timescales.


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