Modeling of Packet Switched Network over TCP Veno: TCP Improvement for Transmission over Wireless Access Networks

摘要

Computer networks form an essential substrate for the multitude of distributed application which is now an essential part of modern business and personal life. It is important to optimize the performance of computer networks, so that users can derive optimum utility from the expertise in network infrastructure. Most networks perform well when lightly used, but problems appear when network load increases. This loss of network performance when a network is heavily loaded is called congestion. Wired networks are becoming an integral part of the Internet. Unlike wireless networks, random packet loss due to bit errors is not negligible in wired networks, and this causes significant performance degradation of transmission control protocol (TCP). We propose and study a novel end-to-end congestion control mechanism called TCP Veno that is simple and effective for dealing with random packet loss. A key ingredient of Veno is that it monitors the network congestion level and uses that information to decide whether packet losses are likely to be due to congestion or random bit errors. Specifically: A). it refines the multiplicative decrease algorithm of TCP Reno—the most widely deployed TCP version in practice—by adjusting the slow-start threshold according to the perceived network congestion level rather than a fixed drop factor and B) it refines the linear increase algorithm so that the connection can stay longer in an operating region in which the network bandwidth is fully utilized, based on extensive network testbed experiments and live Internet measurements.