Note on the feedback control algorithms used in high-speed networks

Abstract

In this article we analyze a linear feedback control algorithm particularly suited to the Available Bit Rate service class in Asynchronous Transfer Mode (ATM) networks. We envisage the development of a closed-loop, fluid approximation model, in which the propagation delay is reflected across the network, while the rate of transmission and the queue occupancy are modeled as fluids. Using a fluid model has the advantage to permit a simplified study of the network behavior. The above model is described with the continuous-time system of delay-differential equations, which is solved semi-analytically. The contribution of this work is to provide a sending rate scheme, which is based on both a rate control function and a suitable fuzzy function for network load and delay. It is shown that the concept of fuzzy set theory can be proved beneficial in the analysis of network load and delay, whose uncertainty is an inherent characteristic. Finally, the developments in the area of time-delay systems control allow to compute exact stability bounds of the Round Trip Time (RTT) and thus to indicate if the connection is in a stable state.

^†E-mail: [email protected]

^‡E-mail: [email protected]

Keywords:

• High-speed networks
• Feedback control algorithms
• Congestion control
• Fuzzy sets

Notes

^†E-mail: [email protected]

^‡E-mail: [email protected]