A new Internet-Draft with implementation guidelines on how to handle UTC
leap seconds in Internet protocols was posted today on the IETF web
site:
"Coordinated Universal Time with Smoothed Leap Seconds (UTC-SLS)",
Markus Kuhn, 18-Jan-06. (36752 bytes)
http://www.ietf.org/internet-drafts/draft-kuhn-leapsecond-00.txt
Background information, FAQ, etc.:
http://www.cl.cam.ac.uk/~mgk25/time/utc-sls/
Abstract:
Coordinated Universal Time (UTC) is the international standard timescale
used in many Internet protocols. UTC features occasional single-second
adjustments, known as "leap seconds". These happen at the end of
announced UTC days, in the form of either an extra second 23:59:60 or a
missing second 23:59:59. Both events need special consideration in
UTC-synchronized systems that represent time as a scalar value. This
specification defines UTC-SLS, a minor variation of UTC that lacks leap
seconds. Instead, UTC-SLS performs an equivalent "smooth" adjustment,
during which the rate of the clock temporarily changes by 0.1% for 1000
seconds. UTC-SLS is a drop-in replacement for UTC. UTC-SLS can be
generated from the same information as UTC. It can be used with any
specification that refers to UTC but lacks provisions for leap seconds.
UTC-SLS provides a robust and interoperable way for networked UTC-
synchronized clocks to handle leap seconds. By providing UTC-SLS instead
of UTC to applications, operating systems can free most application and
protocol designers from any need to even know about UTC leap seconds.
Please have a careful look at the full specification and rationale.
Markus
--
Markus Kuhn, Computer Laboratory, University of Cambridge
http://www.cl.cam.ac.uk/~mgk25/ || CB3 0FD, Great Britain
Received on Wed Jan 18 2006 - 14:17:21 PST