Packet marking for Web traffic in networks with RIO routers

RIO routers, initially proposed in the context of differentiated services networks, distinguish between two classes or packets - in-profile and out-profile - based on a one-bit marking in packet headers. Traditionally, packet-marking is performed by ingress routers according to a user-profile specified in terms of bandwidth. We consider an alternative strategy in which packets are marked based on the state of individual TCP flows. This marking scheme can be implemented either at the end systems or ingress routers (thus avoiding changes at end systems). In addition, we present a variant of our scheme that integrates the Diffserv style packet-marking based on the user-profile. By extensive simulations, we demonstrate that the proposed scheme can significantly reduce the completion time of TCP flows. In particular, the completion time of short TCP flows is halved. These results are consistent over different TCP variants and in the presence of ECN