A Note on the Fairness of Additive Increase and Multiplicative Decrease
Paul Hurley, Jean‐Yves Le Boudec, Patrick Thiran · Infoscience (Ecole Polytechnique Fédérale de Lausanne) · 1998
Some recent papers #5, 9# have shown that congestion control based on additive increase and multiplicative decrease tends to share bandwidth according to proportional fairness. Proportional fairness is a form of fairness which distributes bandwidth with a bias in favour of #ows using a smaller number of hops; this is in contrast with max-min fairness, which gives absolute priority to small #ows. We revisit those results by using the modelling framework based on the ordinary di#erential equation method in #7# and #6#. We #nd that for the case of small increments and constant round trip times, and in the regime of rare negative feedback, the proportional fairness result can only very approximately re#ect the real rate allocation when we assume that the feedback received by sources is independentoftheir sending rates. In the case where sources receive feedback proportionally to their sending rates, and still for sources with identical round trip times, this is no longer true an...