Re: [Ntp] Antw: [EXT] Re: New Version Notification for draft‑gruessing‑ntp‑ntpv5‑requirements‑03.txt

[Miroslav Lichvar <[e-mail]>]

On Tue, Oct 19, 2021 at 11:43:25AM +0200, Ulrich Windl wrote:
> >>> Miroslav Lichvar <[e-mail]> schrieb am 19.10.2021 um 10:17 in
> Nachricht <YW5/KqAZdI+EmlTn@localhost>:
> > That's the Timescale Offset field in my draft. If the selected
> > timescale is UTC or TAI, it contains the TAI‑UTC offset, or 0x8000 if
> > unknown. The expectation is that client will request the timescale
> > which it is using for timestamping of NTP packets.
> 
> Would it be allowable for a stratum-1 server to provide an "unknown TAI
> offset" while still claiming to be "v5"?

Yes, of course. Most systems don't care about TAI.

> It could be a challenge for systems like DCF-77 that do do provide a TAI
> offset.

Right. There are also isolated networks where computers are
synchronized to one another, but only loosely synchronized to UTC
(e.g. manual correction few times per year).

> > If all computer clocks were keeping time in TAI, or at least could
> > convert all their timestamps to TAI, that would make sense. But I
> > think it's more likely that UTC will stop leaping before TAI is
> > adopted everywhere.
> 
> It depends how future OS time APIs will look like.

Right.

One of the requirements for NTPv5 should be that it can be properly
implemented on current versions of all major systems, i.e. TAI cannot
be the only supported timescale.

-- 
Miroslav Lichvar