Adaptive TCP for Effective and Fair Utilization of High Bandwidth-Delay Product Networks

The fairness (or TCP-friendliness) of recent high-speed TCP proposals for high bandwidth-delay product networks is generally poor. We believe that the lack of the TCP-friendliness of high-speed TCP proposals stems from their ineffectiveness in detecting competing TCP ¤ows. We suggest a competition detection mechanism for a single TCP ¤ow to detect the presence of competing TCP ¤ows and propose a new TCP congestion control scheme, called Adaptive TCP (A-TCP), which uses competition detection to control the aggressiveness of the ¤ow. If no competing ¤ows exist, a single A-TCP ¤ow increases its sending rate aggressively in order to highly utilize the network. Otherwise, it becomes a standard TCP to fairly share the network with competing ¤ows. We show that this approach effectively utilizes high bandwidth-delay product networks while remaining TCP-friendly to standard TCP ¤ows. We implemented A-TCP as part of Linux as well as ns2. Experimental results show that A-TCP achieves high network link utilization while retaining better TCP-friendliness than existing high-speed TCP proposals.