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Re: [Ntp] Internet latency mapping project idea

Miroslav Lichvar <mlichvar@redhat.com> Tue, 23 April 2024 12:10 UTC

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Date: Tue, 23 Apr 2024 14:10:05 +0200
From: Miroslav Lichvar <mlichvar@redhat.com>
To: Tamme Dittrich <tamme@tweedegolf.com>
Cc: ntp@ietf.org
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Subject: Re: [Ntp] Internet latency mapping project idea
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On Mon, Apr 22, 2024 at 02:19:24PM +0200, Tamme Dittrich wrote:
> Maybe the collected data could also be used to build better noise models
> for NTP implementations, although I'm not an expert in this area.
> 
> Do you know of any previous work in this area? I would be happy about any
> feedback on the idea.

There are about 800 stratum 1 servers in the pool.ntp.org pool. About
270 have a refid of GPS. From that about 40 claim the smallest
non-zero root dispersion of ~15 microseconds and about 90 claim zero
root dispersion. There is an argument to be made if it's ok to claim
zero, but there are some implementations/devices known to provide
accurate time doing that.

That's what I use when I need to get real-world latency data.

-- 
Miroslav Lichvar

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