The effects of asymmetry on TCP performance

In this paper, we study the effects of network asymmetry on endto -end TCP performance and suggest techniques to improve it. The networks investigated in this study include a wireless cable modem network and a packet radio network. In recent literature (e.g., 16), asymmetry has been considered in terms of a mismatch in bandwidths in the two directions of a data transfer. We generalize this notion of bandwidth asymmetry to other aspects of asymmetry, such as latency and media-access, and packet error rate, which are common in wide-area wireless networks. Using a combination of experiments on real networks and simulation, we analyze TCP performance in such networks where the throughput achieved is not solely a function of the link and traffic characteristics in the direction of data transfer (the forward direction) , but depends significantly on the reverse direction as well. We focus on bandwidth and latency asymmetries, and propose and evaluate several schemes to improve end-to-end ...