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Re: [v6ops] draft-elkins-v6ops-ipv6-pdm-recommended-usage-00

"MORTON JR., ALFRED C (AL)" <acmorton@att.com> Thu, 29 August 2013 16:54 UTC

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From: "MORTON JR., ALFRED C (AL)" <acmorton@att.com>
To: Nalini Elkins <nalini.elkins@insidethestack.com>, joel jaeggli <joelja@bogus.com>, IPv6 Ops WG <v6ops@ietf.org>, "tsv-area@ietf.org" <tsv-area@ietf.org>
Date: Thu, 29 Aug 2013 12:54:10 -0400
Thread-Topic: draft-elkins-v6ops-ipv6-pdm-recommended-usage-00
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Cc: "joachim.fabini@tuwien.ac.at" <joachim.fabini@tuwien.ac.at>, "trammell@tik.ee.ethz.ch" <trammell@tik.ee.ethz.ch>
Subject: Re: [v6ops] draft-elkins-v6ops-ipv6-pdm-recommended-usage-00
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Hi Nalini, thanks for the reference.

I think there may be additional sources of measurement timestamp error.
For example, 

I think the 10us spec is for the (old?) RIPE TTM device timestamps in NTP messages.
Another device uses these timestamps and previous info to steer its clock (+error).
The measurement system mechanics of reading time and inserting timestamps 
in messages (+error).

But under the right conditions, 50us still seems do-able to me.

Al

> -----Original Message-----
> From: Nalini Elkins [mailto:nalini.elkins@insidethestack.com]
> Sent: Thursday, August 29, 2013 8:48 AM
> To: joel jaeggli; MORTON JR., ALFRED C (AL); IPv6 Ops WG; tsv-
> area@ietf.org
> Cc: joachim.fabini@tuwien.ac.at; trammell@tik.ee.ethz.ch
> Subject: Re: draft-elkins-v6ops-ipv6-pdm-recommended-usage-00
> 
> Please take a look at:
> 
> http://www.ripe.net/data-tools/stats/ttm/test-traffic-measurement-service
> 
> 
> Note that what they provide is:
> 
>     * NTP-server, the test-boxes can act a stratum 1 server for the
> machines on your network, providing time-stamps with an accuracy of 10
> microseconds.
> 
> Thanks,
> 
> Nalini Elkins
> Inside Products, Inc.
> (831) 659-8360
> www.insidethestack.com

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