Re: [Ntp] NTPv5 draft

[Kurt Roeckx <[e-mail]>]

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