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

Martin Burnicki <martin.burnicki@meinberg.de> Tue, 08 September 2015 08:45 UTC

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To: Miroslav Lichvar <mlichvar@redhat.com>
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From: Martin Burnicki <martin.burnicki@meinberg.de>
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Date: Tue, 08 Sep 2015 09:43:43 +0200
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Subject: Re: [ntpwg] I-D Action: draft-ietf-ntp-checksum-trailer-02.txt
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Miroslav Lichvar schrieb:
> On Mon, Sep 07, 2015 at 10:28:12AM +0200, Martin Burnicki wrote:
>> Miroslav Lichvar wrote:
>>> I was thinking about detecting network asymmetries on the path between
>>> client and server. If C1 and C2 are not equal, the paths were
>>> different and the source could be rejected in the source selection or
>>> have a smaller weight when combining with others.
>>
>> On the other hand, if the delays in bot directions can be measured
>> separately and this is done properly on the involved nodes then it shouldn't
>> matter if the request and reply packets go over different routes.
>
> I think the correction fields are supposed to include only the
> processing delays. The NTP-aware devices generally can't know the
> network delays between them.

OK, you're right. The constant (cable) delays will also differ and can't 
be determined if the routes differ.

Martin
-- 
Martin Burnicki

Senior Software Engineer

MEINBERG Funkuhren GmbH & Co. KG
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