Analysis of a method for differential TCP service

We have witnessed an increasing interest in providing differentiated Internet services, departing from the traditional notion of fairness in the best effort service model. However research efforts have almost exclusively focused on routers, by enhancing their scheduling and queue management capabilities in order to treat flows according to policies. There has been much less work on transport level approaches to differentiated services. MulTCP, is the only piece of work in this direction known to the authors. In this paper we describe the MulTCP modifications in TCP´s congestion control mechanism, its implementation in a BSD networking stack and present some experiences from a series of experiments over real networks comparing its performance when implemented on different TCP variants. Our results were particularly interesting in the case of RED gateways. We comment on the effectiveness and scalability of the differentiation mechanism and conclude that in certain popular environments the proposed method for transport level differentiation can be both feasible and effective