This paper analyzes the effectiveness of a class of adaptive algorithms for rate control in a data network with the following two elements: many sources with diverse characteristics (e.g., nonadaptive and adaptive sources with different feedback delays, different constraints on transmission rates) and a switch, based on ATM or cell-relay technology, with finite buffers. Several adaptive sources compete among themselves as well as with other nonadaptive sources for bandwidth at a single queue. We first model random fluctuations in the queue-length process due to the nonadaptive sources as Brownian motion, and we show, for a large class of adaptive strategies, how the amount of bandwidth wasted because of idleness and the amount of offered traffic lost because of overflowing buffers scale with the speed of the network. We then model the arrival process of nonadaptive traffic more realistically as a general stochastic fluid with bounded, positive rates. For a class of adaptive strategies with linear adaptation functions, we prove that the results obtained from the Brownian model of randomness extend to cover the more realistic model. This occurs because the adaptive sources induce heavy-traffic conditions (corresponding to the power-maximizing regime of Mitra (1990)) by accurately estimating and using the residual bandwidth not occupied by the nonadaptive traffic. Our analysis gives new insight about how performance measures scale with the variability of the nonadaptive traffic. We illustrate through simulations that queue fluctuations behave as predicted.>

Emerging technologies for high-speed data network provide users with explicit feedback about congestion. Users, however, have questioned whether feedback can help in avoiding congestion in wide-area networks that operate at speeds of multiple megabits- or gigabits-per-second. In this paper we analyze a class of adaptive schemes with delayed feedback, where adaptive sources interact with each other as well as with non-adaptive sources through a single queue. We model the network as a stochastic, delay-differential equation and the rate at which an adaptive source transmits data as a fluid. Our model accounts for different levels of traffic burstiness introduced by the non-adaptive sources and for distinct propagation delays for different adaptive sources. We show how the performance of the system scales with increasing network speeds for quite general fluctuations in the bandwidth available to the adaptive sources. Simulation results show the accuracy of the model's predictions as a function of key parameters. This paper should raise the expectations of users about the potential effectiveness of responding to congestion notification.

In this paper we analyze a class of delayed feedback schemes that achieves the dual goal of keeping buffers small and utilizations high, despite propagation delays and regardless of network rates. We analyze delayed feedback schemes as a system of delay-differential equations, in which we model the queue-length process and the rate at which a source transmits data as fluids. We assume that a stream of acknowledgements carries information about the state of a bottleneck queue back to the source, which adapts its transmission rate according to any monotone function of that state. We show stability for this class of schemes, in that their rate of transmission and queue length rapidly converge to a small neighborhood of the designed operating point. We identify the appropriate scaling of the model's parameters for the system to perform optimally.

The performance of local area networks (LANs) bridged through a virtual-circuit-based wide area network (WAN) is analyzed. The focus is on understanding end-to-end performance issues from an applications point of view. Results that can be used to traffic engineer the network to meet end-user service objectives on interactive response time and bulk data transfer throughput are derived. It is demonstrated that the use of a windowing protocol in the wide area network provides a robust control mechanism for regulating traffic and delivering high performance.>

Proposes and analyzes a method for increasing the efficiency of a slotted multiaccess data communications network. The unique aspect of this method is that high efficiency can be achieved without much increase in latency or complexity at stations. The necessary hooks for its implementation have been incorporated into the distributed queue dual bus (DQDB) protocol, which is being standardized by the IEEE 802.6 Committee for metropolitan area networks (MANs). The proposed method, originally presented as a contribution for the MAN standards, allows slots to be reused once they reach their destination while retaining the inherent low-latency implementation and simple OR write physical interface for stations in the original scheme. The results of tests of network throughput increase as a function of traffic locality and of the number and location of erasure nodes are discussed.>