Performance and buffering requirements of TCP applications in asymmetric networks

Asymmetric networks are defined to be those in the forward (or downstream) and reverse (or upstream) link speeds may assume different values. These types of networks are becoming more prevalent due to the growing penetration of Hybrid Fiber Coal (HFC) and Asymmetric Digital Subscriber Loop (ADSL) systems, in the last mile or local loop. Consequently, it is important to understand and quantify the effect that asymmetry has on the performance of TCP applications. In this paper we study the effect of varying the upstream buffer size on TCP performance. We characterize the maximum achievable throughput as a function of the number of upstream buffers, and also compute the minimum downstream buffer size required to achieve full link throughput.