[154404] in North American Network Operators' Group
RE: F-ckin Leap Seconds, how do they work?
daemon@ATHENA.MIT.EDU (Keith Medcalf)
Tue Jul 3 16:08:51 2012
Date: Tue, 03 Jul 2012 14:08:01 -0600
In-Reply-To: <10203536.12328.1341343627358.JavaMail.root@benjamin.baylink.com>
From: "Keith Medcalf" <kmedcalf@dessus.com>
To: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> > The system clock needs to be UTC, not UTC =C2=B1 some offset stuck
> > somewhere that keeps some form of running tally of the current leap
> > second offset since the epoch.
> Nope. UTC *includes* leap seconds already. It's UT1 that does not.
> Are you suggesting that NTP timekeeping should be based on UT1?
The system clock should be based on UT1 and should be monotonically increas=
ing since this matches the common concept of time. Calculations done with =
this value are all based on it being UT1 and using the "common" notion of U=
T1 rules. The root cause of the difficulties is that someone decided that =
the system clock would not maintain "wall clock" time (UT1) but rather some=
other timebase and then "step" that time to keep it in sync with UT1.
NTP can keep time in UTC (or anything else) if it wants, but it should disc=
ipline the system clock to monotonically increasing UT1.
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