Re: The TCP and UDP checksum algorithm may soon need updating

Michael Thomas <mike@mtcc.com> Wed, 10 June 2020 01:23 UTC

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Subject: Re: The TCP and UDP checksum algorithm may soon need updating
To: ietf@ietf.org
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From: Michael Thomas <mike@mtcc.com>
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Date: Tue, 9 Jun 2020 18:23:18 -0700
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On 6/9/20 6:08 PM, John Levine wrote:
> In article <3ac60a21-4aee-d742-bedc-5be3a4e65471@mtcc.com>om>,
> Michael Thomas  <mike@mtcc.com> wrote:
>> So the long and short of this entire issue seems to be is, is the
>> uncaught error rate serious enough that warrant rethinking weak
>> transport and frankly L2 layer error detection? ...
> Having read the papers that Craig referenced, that's my interpretation.
>
> One of them is about a big physics application which sends multiple
> terabytes of data over the net using what looks like a version of
> FTP that transfers several files at once.  They send the data as a lot
> of of 4 gig files. When they started verifying file checksums, they
> found about 20% of the received files were corrrupted in transit.
>
> In that application they resend the corrupt files and they obviously
> need make the files smaller. But retransmitting a file at a time seems
> a lot less efficient than improving the checksums and using the
> existing TCP packet level retransmission.
>
Which pretty much makes a case for something like transport mode ipsec, 
right? it's a hell of a lot cheaper to drop a packet than retransmit an 
entire file, right?

I guess this gets chalked up to false efficiencies. Thankfully we're a 
point where a lot of these tradeoffs aren't quite as hand-wringing.

Mike