Control-theoretic max-min flow control with minimum rate guarantee

We present a novel control-theoretic explicit rate (ER) allocation algorithm for the max-min flow control of elastic traffic services with minimum rate guarantee in the context of the ATM ABR service. The proposed ER algorithm is simple in that the number of operations required to compute it at a switch is minimized, scalable in that per-VC (virtual circuit) operations including per-VC queueing, per-VC accounting and per-VC state management are virtually removed, and stable in that by employing it the user transmission rates and the network queues are asymptotically stabilized at a unique equilibrium point at which max-min fairness with minimum rate guarantee and target queue lengths are achieved respectively. To improve the speed of convergence we normalize the controller gains of the algorithm by the estimate of the number of locally-bottlenecked VCs. The estimation scheme is also computationally simple and scalable since it does not require per-VC accounting either. We analyze the theoretical performance of the proposed algorithm and verify its agreement with the practical performance through simulations in the case of multiple bottleneck nodes. We believe that the proposed algorithm will serve as an encouraging solution to the max-min flow control not only in the context of ATM ABR service but also in general elastic traffic services.