Re: [LEAPSECS] Internet-Draft on UTC-SLS

From: M. Warner Losh <imp_at_BSDIMP.COM>
Date: Thu, 19 Jan 2006 09:58:55 -0700 (MST)

The biggest objection that I have to it is that NTP servers will be at
least .5s off, which is far outside the normal range that NTP likes to
operate. Unless the prceice interval is defined, you'll wind up with
the stratum 1 servers putting out different times, which ntpd doesn't
react well to.

ntpd runs at a 1024s interval, typically. Depending on when the leap
second is announced, and when it polls, ntpd would see a 1s step
(since the rubber seconds happen over 1000s). It wouldn't believe it
(since it has popcorn outlier rejection). It would then believe the
step after 2048s, but since the step is so large, it would just exit
(depending on the flags given to ntpd). This will lead to *MORE*
clock skew, not less.

I'm also concerned about the fact that many radio time codes do not
announce the leap second pending until the last hour or less. This
makes it hard to propigate out to the non-stratum 1 servers.

It is a horrible idea. It is a horrible kludge and I'm not mollified
by the weak justifications that are given in the "faqcrit." My
concerns are real and valid and this will cause more problems than it
kludges over. It is a terrible idea.

Warner
Received on Thu Jan 19 2006 - 09:01:29 PST