Re: [Ntp] NTPv5 draft

Agree, these fields could use better descriptions or (better) replacement.

One manufacturer (LeoNTP) lowers precision to indicate reduced accuracy and
claims to obey the NTP specification.

Should a stratum 1 NTP server report root distance=0  ?   National labs
differ.

Using NTP short format the smallest non-zero root dispersion is 15
microseconds.  One can argue for finer granularity

Steve Sommars

On Mon, Nov 30, 2020 at 2:03 PM Kurt Roeckx <kurt@roeckx.be> wrote:

> On Mon, Nov 30, 2020 at 08:12:06PM +0100, Dieter Sibold wrote:
> >
> > 3. Traceability
> >
> > It would make sense that the v5-packets optionally provide information
> about
> > the uncertainty of the timestamps taken. These formally for establishing
> > traceability.
>
> The NTPv4 packet contains 3 fields that's related to the
> uncertainty: precision, root delay, root dispersion. I'm not sure if
> anybody is using the precision for anything, but it also has an
> effect on the uncertainty.
>
> I'm wondering if the combination of those 3 fields is useful, and
> if we need other fields to replace them. We at least need some
> specification on how to calculate the values. Is the root distance
> a mean, filtered or last value? Does the dispersion field have a 95%
> (k=2) confidence interval?
>
> > Additionally, in order to maintain traceability during the
> > time period in which leap smearing is applied the client needs to obtain
> the
> > necessary information to calculate the offset between UTC and smeared
> time.
> > This also is mandatory to maintain traceability.
>
> I think the document, at least the version in git, has an
> extension for that.
>
>
> Kurt
>
> _______________________________________________
> ntp mailing list
> ntp@ietf.org
> https://www.ietf.org/mailman/listinfo/ntp
>