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

["Dieter Sibold" <[e-mail]>]

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, [e-mail] wrote:

> 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/
>
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