Subject: Re: [art] Confirm submission of I-D draft-touch-time

From: Martin Burnicki <[email-masked]>
Date: Wed, 31 Jan 2018 15:30:37 +0100

Hi all,

I just saw a link to this discussion, joined the mailing list and try to
reply in the correct thread context, even though I read the previous
emails only in the archive.

Philip Homburg wrote:
> So in the context of NTP, there needs to be a flag of some kind that signals
> that the timestamps in the packet are subject to smear. In the case of an API,
> ideally the system returns that the time is smeared. Or the application
> requests that explicitly.

Indeed, leap smearing has been implemented in ntpd. See:
https://bugs.ntp.org/show_bug.cgi?id=2855
(The site seems to fail while I'm writing this email)

If you are interested, here's a whitepaper that describes the basic
concepts of this implementation, and also contains some test results:
https://www.meinbergglobal.com/download/burnicki/Leap%20Second%20Smearing%20With%20NTP.pdf

Right now this has been implemented as smearing with a cosine shape that
is finished at the end of the leap second. While smearing is in
progress, the "refid" field in the NTP packets sent to clients has a
specific encryption which tells that the NTP server is currently
smearing, and it also contains the current smear offset.

Also, the command "ntpq -c rv" run on the server is telling if smearing
is in progress, and the value of the current smear offset.

Martin
-- 
Martin Burnicki

Senior Software Engineer

MEINBERG Funkuhren GmbH & Co. KG
Email: [email-masked]
Phone: +49 5281 9309-414
Linkedin: https://www.linkedin.com/in/martinburnicki/

Lange Wand 9, 31812 Bad Pyrmont, Germany
Amtsgericht Hannover 17HRA 100322
Geschäftsführer/Managing Directors: Günter Meinberg, Werner Meinberg,
Andre Hartmann, Heiko Gerstung
Websites: https://www.meinberg.de  https://www.meinbergglobal.com
Training: https://www.meinberg.academy

---

From: Joe Touch <[email-masked]>
Date: Wed, 31 Jan 2018 08:28:31 -0800

Martin,

Can you help clarify whether this is an update to the NTP protocol or
merely an update to the user libraries that are provided with it?

(i.e., AFAICT, smearing is a local function that doesn't involve
synchronization per se, but does rely on NTP-like sync of time outside
the smearing period as well as external input on planned leap events)

Joe

---

From: Steffen Nurpmeso <[email-masked]>
Date: Wed, 31 Jan 2018 21:49:09 +0100

Joe Touch <[email-masked]> wrote:
  ...
 |(i.e., AFAICT, smearing is a local function that doesn't involve
 |synchronization per se, but does rely on NTP-like sync of time outside
 |the smearing period as well as external input on planned leap events)

As far as i know nothing except the fully-blown and slow RFC 7808
tzdist (untested) and Poul-Henning Kamp's leap DNS record idea as
posted on leapsecs@ helps to avoid the downloading and parsing of
the IERS leapseconds file on your own if you want to include
leapsecond notification in a daily report, on at least systems
which were off overnight.

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)

---

From: Joe Touch <[email-masked]>
Date: Wed, 31 Jan 2018 12:56:55 -0800

Hi Steffens,

Leap seconds are introduced months in advance. Short of a new boot, there should not be an urgent need to update that info so rapidly. 

It would be useful to have more efficient ways to do that update though. 

Joe

> On Jan 31, 2018, at 12:49 PM, Steffen Nurpmeso <[email-masked]> wrote:
> 
> _______________________________________________
> art mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/art