Hi Phillip,
For those who are interested in the proceedings, they took place
yesterday at the ITU's Radio Advisory Group (RAG). The United States
introduced the proposal to do away with leap seconds. They were not,
shall we say, universally supported. Those in favor were largely in
line with what you wrote below, Phillip. Those opposed were not clear
that there really was a problem to solve, and wanted more time to
consult. The matter was referred back to the study group for further
consideration, as well as broader consultation, and will be taken up
again at the next RAG (approximately two years from now).
If you have a TIES account at the ITU, you can listen to the proceedings
by going to the following link and moving to time index 1:43:15 or so.
http://www.itu.int/ibs/ITU-R/RA12/links/1-20120119-1400-en.smil
Regards,
Eliot
On 1/20/12 3:20 PM, Phillip Hallam-Baker wrote:
If we are ever going to get a handle on Internet time we need to get
rid of the arbitrary correction factors introduced by leap seconds.
The problems caused by leap seconds are that they make it impossible
for two machines to know if they are referring to the same point in
future time and quite often introduce errors in the present.
1) No machine can determine the number of seconds between two
arbitrary UTC dates in the future since there may be a leap second
announced.
2) If Machine A is attempting to synchronize with machine B on a
future point in time, they cannot do so unless they know that they
have the same view of leap seconds. If a leap second is announced and
only one makes the correction, an error is introduced.
3) In practice computer systems rarely apply leap seconds at the
correct time in any case. There is thus a jitter introduced around the
introduction of leap seconds as different machines get an NTP fix at
different points in time.
4) Even though it is possible to represent leap seconds correctly in
standard formats, doing so is almost certain to exercise code paths
that should be avoided.
Since the ITU does not look like sorting this out, I suggest we do so
in the IETF. There is no functional reason that Internet protocols
should need leap seconds.
I suggest that the IETF plan to move to Internet Time in 2015,
immediately after the next ITU meeting. Internet time would be TAI
plus the number of leap seconds that have accumulated up to the next
ITU decision point. So if UTC drops leap seconds at the next meeting
the two series will be in sync, otherwise there will be a divergence.
--
Website: http://hallambaker.com/
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