Impact of cell discard strategies on TCP/IP in ATM UBR networks

In ATM UBR networks supporting TCP traffic, optimal efficiency can only be envisaged if switches adopt a discard mechanism that operates at the packet level rather than the cell level. In this paper, we investigate the performance of the EPD, RED and FBA strategies by means of simulation, and give comparative results with respect to different environments and performance criteria. We show that implementing such a strategy in a LAN brings little added value, while the benefit is more obvious in a WAN access network with asymmetrical bandwidths. Specifically, the improvement not only concerns goodput but also fairness among competing TCP connections, and depends upon the Maximum Segment Size used by the sources.