Handling Two-Way TCP Traffic in Asymmetric Networks

The TCP congestion control protocol is mainly designed for bandwidth symmetric paths. As two-way asymmetric connections will probably become common case in the future with the widespread use of ADSL, satellites and other high-speed technologies, it is important to make sure that congestion will be properly handled in these environments. To this end, we propose in this paper a new Adaptive Class-based Queuing mechanism called ACQ for handling two-way TCP tra c over links that exhibit bandwidth asymmetry. ACQ runs at the entry of the slow link and relies on two separate classes, one for ACK packets and one for Data packets. ACQ proposes to adapt the weights of both classes according to the crossing tra c in order to maximize some utility function de ned by the user or the network operator. We show by simulations that our mechanism is able to reach a good utilization of the available resources, managing then to maximize the satisfaction of the user of such asymmetric connections.