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

Martin Burnicki <martin.burnicki@meinberg.de> Mon, 07 September 2015 08:48 UTC

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To: Greg Dowd <Greg.Dowd@microsemi.com>, Miroslav Lichvar <mlichvar@redhat.com>, Tal Mizrahi <talmi@marvell.com>
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From: Martin Burnicki <martin.burnicki@meinberg.de>
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Date: Mon, 07 Sep 2015 10:23:41 +0200
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Subject: Re: [ntpwg] I-D Action: draft-ietf-ntp-checksum-trailer-02.txt
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Greg Dowd wrote:
> Probably moving further offtopic but why would you need 2?  And why
> the counters?  The correction field in PTP was originally designed
> because the hardware couldn't update the timestamps on the fly.  It
> would post-process and then send a follow-up with the precise
> timestamp.   NTP supports that  with the interleave mode.

IMO the interleave mode is just a hack.

"Interleaved mode can be used only in NTP symmetric and broadcast 
modes", quoted from
https://www.eecis.udel.edu/~mills/ntp/html/xleave.html

I really like Miroslav's idea. If support for latency compensation is 
introduced then it would be good to not just introduce a first level 
compensation now and another level later, but just provide a way which 
allows for the highest degree of accuracy.

Martin
-- 
Martin Burnicki

Senior Software Engineer

MEINBERG Funkuhren GmbH & Co. KG
Email: martin.burnicki@meinberg.de
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Lange Wand 9, 31812 Bad Pyrmont, Germany
Amtsgericht Hannover 17HRA 100322
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