Re: [ntpwg] I-D Action: draft-ietf-ntp-checksum-trailer-02.txt

[Miroslav Lichvar <[e-mail]>]

On Mon, Aug 31, 2015 at 02:04:46PM +0000, Tal Mizrahi wrote:
> >With 1 byte for C1/C2 and 8 bytes for D1/D2 in the NTP timestamp format that
> >would be 18 bytes of data. That would fit in the padding in the proposed
> >checksum complement field if you were interested in a more general form of
> >the "timestamp correction" field.
> >
> 
> The purpose of the current draft is to make life easier for HW-based timestamping. HW-based timestamping on the client+server side can significantly improve the clock accuracy. 
> I agree that on-path support (transparent clocks) can improve the accuracy further, but that is not the purpose of the current draft...

Understood. I was just thinking the checksum complement would be
useful for other time stamping corrections too (not just for HW
timestamping on the server or the client) and some of the padding
could be put to use.

> BTW, speaking of transparent clocks, wouldn't it be simpler to add an extension field with a <correction field>, as done in PTP?

That's basically what I'm proposing :). But in NTP we need two fields,
one for the request and one for the reply. The C1 and C2 counters
would I think be a useful addition to that.

-- 
Miroslav Lichvar
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