ADAPTIVE ALGORITHMS FOR FEEDBACK-BASED FLOW-CONTROL IN HIGH-SPEED, WIDE-AREA ATM NETWORKS

This paper gives a class of flow control algorithms for the adaptive a llocation of bandwidths to virtual connections (VC) in high-speed, wid e-area ATM networks, The feedback rate to the source from the network is parsimonious, with each feedback bit indicating whether the buffer at a distant switch is above or below a threshold. The service discipl ine at the switch is First-Come-First-Served. The important goal of ad aptability aims to make all of the network bandwidth available to the active VC's, even though the number of such VC's is variable over a gi ven range. Each VC has two parameters, one giving its minimum guarante ed bandwidth and the other is the weight for determining its share of the uncommitted bandwidth. Judicious selection of these parameters def ines distinctive services, such as Best Effort and Best Effort with Mi nimum Bandwidth, We derive design rules for selecting the parameters o f the algorithms such that the appropriate guarantees and fairness pro perties are exhibited in the dynamical behavior, The systematic use of ''damping'' in right proportion with ''gain'' is shown to be a powerf ul device for stabilizing behavior and achieving fairness, Our analyse s are based on a simple analytic fluid model composed of a system of f irst-order delay-differential equations, which reflect the propagation delay across the network. Extensive simulations examine the following : (1) fairness, especially to start-up VC's; (2) oscillations; (3) tra nsient behavior, such as the rate of equalization from different initi al conditions; (4) disparate bandwidth allocations; (5) multiple paths with diverse propagation delays; (5) adaptability and robustness with respect to parameters; and (7) interoperability of different algorith ms.