Subject: [Ntp] Routing asymmetries in v5

From: Watson Ladd <[email-masked]>
Date: Sun, 12 Apr 2020 18:42:02 -0700

Definitely it should be a draft! I'm happy to write text to make it so.

It seems that corrections are discarded if asymmetric and I don't
think this is necessary. If we have all the boxes speaking NTPv5
corrections, then the routing delay in the boxes should be compensated
out and the correction field will properly adjust the measurements.
Maybe I'm missing something.

Sincerely,
Watson

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From: Daniel Franke <[email-masked]>
Date: Mon, 13 Apr 2020 00:03:03 -0400

> Definitely it should be a draft! I'm happy to write text to make it so.

If you or anyone else wants to run with this and turn it into a full
spec, by all means go for it. Put yourself as lead author and put me
second. Otherwise I'll probably do it myself eventually but I don't
know when.

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From: Daniel Franke <[email-masked]>
Date: Mon, 13 Apr 2020 10:44:52 -0400

> Maybe I'm missing something.

I don't think "all the boxes speaking NTPv5 corrections" is something
that's ever likely to happen. The situation I was worried about when I
added the CRC stuff is that boxes on one path are doing corrections
and the ones on the other aren't, in which the case the correction is
going to make the asymmetry worse as often as it makes it better. But
maybe you're right; I think this is an issue that would benefit from
implementations and experiments.

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From: Danny Mayer <[email-masked]>
Date: Mon, 13 Apr 2020 22:19:08 -0400

> Maybe I'm missing something.
I don't understand this at all. NTP has always assumed that the routing
is asymmetric and does it's best to accommodate that. I'm not sure what
that has to do with the intermediate boxes, there are always multiple
ones unless you are on a LAN, but that's not the common case. Yes the
boxes will add delays as well, as will buffering, congestion and for
that matter lost packets. Why are you discussing something so
fundamental to the NTP archtecture that it was designed to take account
of it?

Danny