Protecting Small Flows from Large Ones for Quality of Service

A simple strategy for improving Quality of Service is to protect small flows from large ones, by finding a small number of large flows, separating them from the remaining traffic, and giving the small flow traffic priority over these large flows. This is a very powerful technique because it is known that a small proportion of all flows (e.g. 0.1%) contain a large proportion of all bytes (e.g. 20%). Many questions arise when this method of managing performance is considered. These questions are investigated by means of a mathematical model of traffic and of queueing in routers. One particular question is particularly emphasized in this paper: how should the size of flows be measured?