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[Ntp] Antwort: Re: The bump, or why NTP v5 must specify impulse response

kristof.teichel@ptb.de Tue, 21 April 2020 10:25 UTC

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From: kristof.teichel@ptb.de
To: Hal Murray <hmurray@megapathdsl.net>
Cc: Kurt Roeckx <kurt@roeckx.be>, ntp@ietf.org
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Subject: [Ntp] Antwort: Re: The bump, or why NTP v5 must specify impulse response
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Moreover, I think it's always good to ensure that if you demand a certain performance level, you can give at least a description of a proof that that performance level can in fact be reached.

I also agree with Hal that the specification of performance guarantees is going to be tricky, since you're going to have to assume a lot of parameters.
Easiest is probably to formulate guarantees dynamically depending on achieved message in-flight roundtrip time per exchange, but even then you're making assumptions about the drift and other behavior of the client's clock between the two timestamps that it takes.


Best regards,
Kristof



-----"ntp" <ntp-bounces@ietf.org> schrieb: -----
An: "Kurt Roeckx" <kurt@roeckx.be>
Von: "Hal Murray"
Gesendet von: "ntp"
Datum: 17.04.2020 23:25
Kopie: ntp@ietf.org, hmurray@megapathdsl.net
Betreff: Re: [Ntp] The bump, or why NTP v5 must specify impulse response

kurt@roeckx.be said:
> Maybe it's useful to have performance guarantees specified, but leave the
> algorithm how to get there either to the implementations, or in a separate
> document.

If you are going to discuss performance guarantees, you have to start with a
description of the input data.

How would you describe the traffic parameters of the internet?

You also get to consider the effects of temperature on the system crystal.  I
think I could at least come up with some parameters for that.

Interrupt latency, Scheduler, ...


--
These are my opinions.  I hate spam.



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