Integrated control of connection admission, flow rate, and bandwidth for ATM based networks

Abstract

We consider the combined control problem of connection admission, flow rate, and bandwidth allocation (capacity, service-rate) under nonstationary conditions. A fluid flow model in state variable form describes the time varying mean behaviour of Available Bit Rate (ABR) traffic, which competes with Guaranteed Traffic for network resources. Using nonlinear control we derive an integrated control strategy, for the finite buffer and finite server case, that is insensitive to any propagation delay. We also derive bounds on mix between ABR and Guaranteed traffic to ensure that control strategy is effective, and select control design variables which can be used to influence the delivered QoS. The performance of proposed scheme is evaluated using analysis and simulation. Simulation results show that it achieves effective server and buffer utilisation (as predicted by analysis) and by appropriate choice of control design variables achieves prescribed bounded delays (for Guaranteed traffic only) and zero cell loss (even for ABR traffic demands exceeding server capacity, which if not controlled would cause losses). Hence proposed scheme delivers guaranteed QoS to user and avoids retransmissions, thus increasing network utilisation.