Re: [Ntp] NTPv5 draft

[Miroslav Lichvar <[e-mail]>]

On Mon, Nov 30, 2020 at 02:32:35PM -0600, Steven Sommars wrote:
> 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.

I think that's just a workaround for limited resolution of the root
dispersion field. That's no longer a problem with the NTPv5 draft,
where the field has a resolution of 3.7 nanoseconds.

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

If we ignore rounding, then no, there is no single clock that can
claim to be perfectly accurate to UTC. I think the only case where it
makes sense to report a dispersion and delay of exact zero is a clock
in the local/orphan mode, which is the "true" time for an isolated
network.

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

The draft does that.

-- 
Miroslav Lichvar