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

Craig Partridge <> Thu, 11 June 2020 18:26 UTC

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From: Craig Partridge <>
Date: Thu, 11 Jun 2020 12:26:12 -0600
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Subject: Re: The TCP and UDP checksum algorithm may soon need updating
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Two comments on the several notes that have gone past.

Michael Thomas raises a point about bugs.  He's quite right and there's
reason to believe that if we tracked the Internet paths on which checksum
errors took place, and compared the paths to find commonalities, we'd
locate broken/buggy equipment.  Jonathan Stone did some of that 20 years
ago and found a software bug in a vendor TCP (which the vendor updated in a
matter of days -- kudos to them) and a network interface vendor who was
shipping cards with defective hardware (and adamantly claimed our
measurements identifying their cards were wrong).

There was also a note (which I can't seem to find) to the effect of "the
errors in the papers don't match what I'm seeing on my systems."  That's
not a surprise.  Errors cluster around particular links or devices.
There's also some reason to believe error rates are higher on the fast
links.  So, depending on your environment and where your traffic goes, your
error rates may vary widely.  All the more reason to measure.


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