Re: [tcpm] draft-eggert-tcpm-historicize-00

Fernando Gont <fernando@gont.com.ar> Sat, 26 June 2010 07:18 UTC

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Date: Sat, 26 Jun 2010 04:17:53 -0300
From: Fernando Gont <fernando@gont.com.ar>
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To: Joe Touch <touch@isi.edu>
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Cc: tcpm@ietf.org, "Anantha Ramaiah \(ananth\)" <ananth@cisco.com>, "Biswas, Anumita" <Anumita.Biswas@netapp.com>
Subject: Re: [tcpm] draft-eggert-tcpm-historicize-00
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Joe Touch wrote:

>> Our expirience has shown, that TCP often runs over links with much
>> higher error rates, than intended for the technology (ie. Design goal of
>> BER <= 1E-12 over Ethernet often has an actual BER >> 1E-12). If such
>> error-prone links are running at a high speed and with large segment
>> sizes (jumbo / giant frames), there exists the real problem that within
>> a short timeframe (weeks to months), TCP will deliver corrupted data, as
>> CRC-16 was not able to catch the error.
> 
> Just to confirm, is this a measured problem or a mathematical one? I.e., have
> you seen this actually occur (i.e., TCP with invalid CRC-16 but valid checksum)
> in the wild, in a lab, or have you never seen it but consider it important anyway?

IIRC, wasn't this sort of what the SIGCOMM (?) paper "when the checksum
and CRC disagree" (authored by J. Stone) was about?

Just my two cents,
-- 
Fernando Gont
e-mail: fernando@gont.com.ar || fgont@acm.org
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