How to mark fairly

A network router that marks packets to signal congestion should do so fairly. We propose a deenition of fairness, using ideas from eeective band-width theory and economics. Our deenition measures both the level of congestion at a router and the contribution of each ow to that congestion, taking into account the ow's burstiness. We then use large deviations to analyse marking algorithms such as red, point out how they can be unfair, and suggest how they can be made fairer.