[e2e] Reacting to corruption based loss

Wesley Eddy weddy at grc.nasa.gov
Tue Jun 7 04:18:09 PDT 2005

On Tue, Jun 07, 2005 at 09:22:32AM +0200, Michael Welzl wrote:
> Also, it has been noted several times (and in several places) that
> AIMD would work just as well if beta (the multiplicative decrease
> factor) was, say, 7/8 instead of 1/2. For a historical reason (I
> think it was the DECbit scheme), 7/8 seems to be a number
> that survived in people's minds.
> So, why don't we just decide for a pragmatic approach instead
> of waiting endlessly for a research solution that we can't come
> up with? Why don't we simply state that the reaction to corruption
> has to be: "reduce the rate by multiplying it with 7/8"?

This idea is sort of discussed in the ETEN paper Craig sent a link to
earlier.  One approach that it describes (CETEN_A) adapts beta between
1/2 and 1 based on the rate of congestion events reported.  In the
October 2004 CCR, there is a paper that goes into greater depth on
CETEN; "New Techniques for Making Transport Protocols Robust to
Corruption-Based Loss" by Eddy, Ostermann, and Allman.

Another idea, called CETEN_P, involes leaving beta the same, but
flipping a coin weighted with the frequency of corruption events
relative to congestion events.  The multiplicative decrease is either
triggered or not triggered depending on the coin flipping outcome.  This
was found to have some flaws that CETEN_A does not share.  See 3.1 of:


Wesley M. Eddy
Verizon FNS / NASA GRC
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