Subject: [ntpwg] Leap seconds file

From: Brian Haberman <[email-masked]>
Date: Tue, 5 Apr 2016 16:19:28 -0400

All,
     During Denis' presentation today, there was a question about the
validity of http://www.ietf.org/timezones/data/leap-seconds.list. It
turns out that the info available in that file is pulled from the IANA
timezone information found at http://www.iana.org/time-zones. The README
states it is non-authoritative, but it appears to be as close to the
authoritative information as I can find.

Just passing info along...

Brian

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From: David Malone <[email-masked]>
Date: Tue, 5 Apr 2016 21:59:27 +0100

> authoritative information as I can find.

There seem to be a few people providing leap seconds information
in this format at the moment:

	https://www.ietf.org/timezones/data/leap-seconds.list
	ftp://tycho.usno.navy.mil/pub/ntp/leap-seconds.list
	ftp://time.nist.gov/pub/leap-seconds.list
	https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list

I guess technically, it is probably the IERS who are making the
decision about when leap seconds are, but I think they are relatively
new to the game of providing a file for ntp.

If anyone is interested, I've written up some of my measurements
of the NTP network's behaviour during leap seconds, which includes
some comments on the leap second file:

	http://www.maths.tcd.ie/~dwmalone/p/tma2016.pdf

David.

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From: Warner Losh <[email-masked]>
Date: Tue, 5 Apr 2016 17:48:15 -0600

> new to the game of providing a file for ntp.

IETF is relatively a newbee too at providing this file. USNO has been
providing this info for a while now, but in different formats. NIST has
been doing in this format for at least two decades, but that's just because
Judah's Lavine is there and his keen interest in ntpd. It's the canonical
source of the file, even if IERS is the canonical source of the data used
to generate the file. This distinction a relic of the days when Bulletin C
received by people who had to do things based on it. :)

Warner