Improving ensemble-TCP performance on asymmetric networks

For the World Wide Web, the transmission control protocol (TCP) and the hypertext transfer protocol (HTTP) are two important protocols. However, interactions between these two protocols, combined with the bandwidth asymmetry of network access technologies such as ADSL, can lead to inefficient HTTP/TCP performance. This paper investigates the effects of bandwidth asymmetry on ensemble-TCP, a protocol designed to coordinate multiple HTTP/TCP connections to improve Web document transfer performance. The evaluation is conducted using the ns-2 network simulator. The paper also proposes and evaluates two new schemes, ACC-ensemble and AF-ensemble, to improve ensemble-TCP performance on asymmetric networks. The simulation results show that AF-ensemble and ACC-ensemble perform better (often 10-50% faster) than Reno TCP and ensemble-TCP for typical user-level Web browsing activity on asymmetric networks