Balancing TCP buffer vs parallel streams in application level throughput optimization

Abstract

The end-to-end performance of TCP over wide-area may be a major bottleneck for large-scale network-based applications. Two practical ways of increasing the TCP performance at the application layer is using multiple parallel streams and tuning the buffer size. Tuning the buffer size can lead to significant increase in the throughput of the application. However using multiple parallel streams generally gives better results than optimized buffer size with a single stream. Parallel streams tend to recover from failures quicker and are more likely to steal bandwidth from the other streams sharing the network. Moreover our experiments show that proper usage of tuned buffer size with parallel streams can even increase the throughput more than the cases where only tuned buffers and only parallel streams are used. In that sense, balancing a tuned buffer size and the number of parallel streams and defining the optimal values for those parameters are very important. In this paper, we analyze the results of different techniques to balance TCP buffer and parallel streams at the same time and present the initial steps to a balanced modeling of throughput based on these optimized parameters.