Subject: [Ntp] I-D Action: draft-aanchal-time-implementation-guidance-01.txt

From: [email-masked]
Date: Mon, 22 Oct 2018 12:10:49 -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           : On Implementing Time
        Authors         : Aanchal Malhotra
                          Kristof Teichel
                          Martin Hoffmann
                          Willem Toorop
	Filename        : draft-aanchal-time-implementation-guidance-01.txt
	Pages           : 9
	Date            : 2018-10-22

Abstract:
   This document describes the properties of different types of clocks
   available on digital systems.  It provides implementors of
   applications with guidance on choices they have to make when working
   with time to provide basic functionality and security guarantees.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-aanchal-time-implementation-guidance/

There are also htmlized versions available at:
https://tools.ietf.org/html/draft-aanchal-time-implementation-guidance-01
https://datatracker.ietf.org/doc/html/draft-aanchal-time-implementation-guidance-01

A diff from the previous version is available at:
https://www.ietf.org/rfcdiff?url2=draft-aanchal-time-implementation-guidance-01

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: "Dieter Sibold" <[email-masked]>
Date: Wed, 31 Oct 2018 20:09:07 +0100

I appreciate the intention of this document and I think this can be a 
very valuable document. But from my point of view Sec. 5 and 6 currently 
are somewhat short for a real helpful guidance for implementors. The 
approach using relative time is interesting; but it misses to indicate 
the possibility to syntonize clocks. Especially, I missed a discussion 
for the situation for using relative time in time synchronized systems. 
The reason is that it is  nearly unimaginable to operate computer 
systems unsynchronized. Usually, regulations such as ISO/IEC 27002 
enforce the need to synchronize your systems to an external time 
reference.

Other comments:

- Sec. 2, last paragraph. I would claim that e.g. ITU-R TF.686-3 define 
most of the terms used in this document.

- Sec. 3.2, second paragraph: I would suggest to replace „rate of 
passage …“ with frequency or even better with the term „clock 
rate“

- Sec. 4. I don’t get the meaning of the first sentence. Is it 
possible to rephrase in order to make it easier to understand?

- Sec. 4.2, 5th paragraph, last sentence. Chrony, OpenNTP are all more 
or less complete implementations of NTP and not different time protocols 
as implied by this sentense.

- Sec. 4.2, 7th paragraph. I would think, that adjusting time zone 
offsets is not to be compared to the manuell adjustment to what is 
called the world clock.

- Sec. 5, last paragraph: an application may rely on timing over short 
and long time periods depending on the specific situation. So this is 
not only application but also depending upon the specific situation.

- Sec. 6.1 introduce the term „raw time“ without definition

Dieter

On 22 Oct 2018, at 21:10, [email-masked] wrote:

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