Subject: [Ntp] I-D Action: draft-stenn-ntp-leap-smear-refid-02.txt

From: [email-masked]
Date: Mon, 25 Mar 2019 17:41:16 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Network Time Protocol WG of the IETF.

        Title           : Network Time Protocol Leap Smear REFID
        Author          : Harlan Stenn
	Filename        : draft-stenn-ntp-leap-smear-refid-02.txt
	Pages           : 5
	Date            : 2019-03-25

Abstract:
   Leap Seconds are part of UTC.  NTP timestamps are based on POSIX
   timestamps, which require each day to have exactly 86,400 seconds per
   day.  Some applications and environments choose to "smear" leap
   second corrections over a period that can last up to 24 hours' time,
   and implement NTP servers that offer smeared time to clients asking
   them for the time.

   Both NTP clients and operators have no current way to tell if an NTP
   server is offering leap-smeared time or not.  This is a problem.

   Similarly, an NTP server may choose to offer leap-smeared time to
   clients that do not appear to know that a leap event is in-process.
   This is a problem.

   This proposal offers a mechanism that provides a simple and clean
   solution to problems, by giving a way that clients (and operators)
   can trivially ask for leap-smeared time and detect a server that is
   offering leap-smeared time.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-stenn-ntp-leap-smear-refid/

There are also htmlized versions available at:
https://tools.ietf.org/html/draft-stenn-ntp-leap-smear-refid-02
https://datatracker.ietf.org/doc/html/draft-stenn-ntp-leap-smear-refid-02

A diff from the previous version is available at:
https://www.ietf.org/rfcdiff?url2=draft-stenn-ntp-leap-smear-refid-02

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

---

From: "Ulrich Windl" <[email-masked]>
Date: Tue, 26 Mar 2019 08:16:06 +0100

>>> <[email-masked]> schrieb am 26.03.2019 um 01:41 in Nachricht
<[email-masked]>:

> A New Internet‑Draft is available from the on‑line Internet‑Drafts
directories.
> 	Filename        : draft‑stenn‑ntp‑leap‑smear‑refid‑02.txt
> 	Pages           : 5
> 	Date            : 2019‑03‑25
> 
> Abstract:
>    server is offering leap‑smeared time or not.  This is a problem.

What about "...eared time or not, causing problems."?
Does it make sense to distinquish between clients and operators? I mean most
RFCs do not deal with problems humans may have: If the client (software) is
fixed, the operator should be happy, too ;-)

> 
>    Similarly, an NTP server may choose to offer leap‑smeared time to
>    clients that do not appear to know that a leap event is in‑process.
>    This is a problem.

Maybe add the kind of problem to the abstract: The frequency correction may
get confused, and an additional leap second might be applied in non-smear-aware
clients.

>    can trivially ask for leap‑smeared time and detect a server that is
>    offering leap‑smeared time.

The more often I read about that, the less is like the "smear" term. Is
another maybe more technical term possible?

Regards,
Ulrich

> https://datatracker.ietf.org/doc/draft‑stenn‑ntp‑leap‑smear‑refid/ 
> 
> https://tools.ietf.org/html/draft‑stenn‑ntp‑leap‑smear‑refid‑02 
> https://datatracker.ietf.org/doc/html/draft‑stenn‑ntp‑leap‑smear‑refid‑02 
> 
> https://www.ietf.org/rfcdiff?url2=draft‑stenn‑ntp‑leap‑smear‑refid‑02 
> 
> 
> Internet‑Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet‑drafts/ 
> 
> _______________________________________________
> ntp mailing list
> [email-masked] 
> https://www.ietf.org/mailman/listinfo/ntp

---

From: Harlan Stenn <[email-masked]>
Date: Tue, 26 Mar 2019 00:38:39 -0700

> What about "...eared time or not, causing problems."?

I don't understand your question.

> fixed, the operator should be happy, too ;-)

I think so.  An NTP instance may care very much about the time it wants
to follow during a leap second.  And operators separately want to be
able to quickly and clearly see what systems are offering correct or
leap-smeared time.

> get confused, and an additional leap second might be applied in non-smear-aware

Perhaps to the Introduction.  I just spent a lot of time and effort
making the Abstracts much shorter, as people complained that there was
too much information in there.
> another maybe more technical term possible?

It's the only term I've ever seen used.

Thanks for your comments.

H
--

-- 
Harlan Stenn, Network Time Foundation
http://nwtime.org - be a Member!

---

From: Martin Burnicki <[email-masked]>
Date: Tue, 26 Mar 2019 09:17:43 +0100

> fixed, the operator should be happy, too ;-)

The basic idea with leap second smearing was to hide the leap second
from the clients, so that the clients are spoofed and don't even notice
when a leap second occurs.

In my opinion it's totally up to the operators to select smearing
servers for clients that are to be spoofed because they can't handle a
leap second correctly, or run applications that are confused if the
system time steps back by 1 s because a leap second is inserted, or
select "normal" servers for clients that can handle a leap second properly

> another maybe more technical term possible?

I think smearing is the word that is used in most cases. If you choose a
different word here then folks who are less familiar with this kind of
stuff may not easily associate the RFC with leap second smearing.

Martin
-- 
Martin Burnicki

Senior Software Engineer

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