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[Ntp] Antw: [EXT] Re: NTPv5 draft

Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de> Tue, 01 December 2020 12:32 UTC

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Date: Tue, 01 Dec 2020 13:32:44 +0100
From: Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>
To: mlichvar@redhat.com, kurt@roeckx.be
Cc: Dieter Sibold <dsibold.ietf@gmail.com>, "ntp@ietf.org" <ntp@ietf.org>
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Subject: [Ntp] Antw: [EXT] Re: NTPv5 draft
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>>> Kurt Roeckx <kurt@roeckx.be> schrieb am 01.12.2020 um 11:25 in Nachricht
<20201201102540.GO971977@roeckx.be>:
> On Tue, Dec 01, 2020 at 11:03:05AM +0100, Miroslav Lichvar wrote:
>> On Tue, Dec 01, 2020 at 10:51:22AM +0100, Dieter Sibold wrote:
>> > Uncertainty and maximum error are different. The uncertainty interval will
>> > always be smaller or equal to the max. error.
>> 
>> Can you describe an example how would the server determine the
>> uncertainty?
> 
> When talking about uncertainty, we talk about confidence interval.
> We can never be sure what the maximum error is. We typically talk
> about an expanded uncertainty of 95%, saying that in 95% of the
> cases the error will be smaller than the uncertainty.
> 
> The 95% comes from 2 * sigma, which covers 95.45%. And we'll write
> that as k=2 in case of a normal distribution. For NTP, in most
> cases, it will not be a normal distribution, and you'll need a
> different k factor for the 95%.

Hi!

Yes, but which? How to get the right number?

Regards,
Ulrich

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