A study of fairness for ATM ABR service based on cell delay

A general goal of the Asynchronous Transfer Mode (ATM) network is to support connections across Local-Area Networks (LANs), Metropolitan-Area Networks (MANs), and Wide-Area Networks (WANs). However in Available Bit Rate (ABR) service, different treatments are offered according to different Round Trip Times (RTTs) of connections. To improve the above "unfairness," this paper presents ABR DELAY mechanism, in which three reference parameters for cell delay are defined, and reflect on the messages of Resource Management (RM) cells. To evaluate our mechanism, we execute simulations on a simple ATM network model where six TCP connections and a background traffic with different RTTs share the bandwidth of a bottleneck link. The simulation results, based on TCP goodput and efficiency, clearly show that ABR DELAY mechanism, improves the fairness among TCP connections, although the considered implementation of ABR transfer capacity is simple.