On Dimensioning Asymmetric Access Links

Asymmetric forward and reverse link bandwidths in access networks are characteristic of many access technologies and commonly seen in Internet Access service offerings. For many existing and emerging Internet-based applications, TCP is the predominant transport-layer protocol and its performance is critical to the usability of many of these applications. Thus, the ability of many Internet access service providers to control the bandwidth asymmetries seen by TCP flows— whose throughputs can be degraded by such asymmetry—presents the problem of how asymmetry should be controlled to ensure optimal TCP performance. Through the formulation of an optimization problem and the generation of a series of simulation results, guidelines for dimensioning access links are developed and insights into the efficiency of TCP in asymmetric access networks are obtained.