Performance analysis and improvement of TCP proxy mechanism in TCP overlay networks

TCP overlay networks that control data transmission quality at the transport layer are being paid a lot of attention as users´ demands for diversified Internet services increase. They are expected to enhance the end-to-end throughput of the TCP connection essentially because the round trip times and the packet loss ratios of each split TCP connection are reduced. However, performance degradation may occur due to undesired interactions among the split TCP connections. We introduce an analysis approach to estimate end-to-end throughput of data transmission with a TCP proxy mechanism considering performance degradation. Our analysis results reveal that we confirm the effect of the TCP proxy mechanism. We also find that we cannot ignore performance degradations due to interactions among split TCP connections, especially when the congestion level of the network they traverse is small. Further, we clarify that we should take into account the packet loss ratios, performance degradations and propagation delays of the network when we consider issues relating to the design of TCP overlay networks.