Decentralized Control Scheme For Large-Scale ATM Networks
Lorne G. Mason, Anne Pelletier, Eric Létourneau · 1998
Two approaches are proposed in this paper in order to facilitate network access control in large-scale ATM networks. We consider the centralized isarithmic control scheme that controls the total number of cells in the network using a permit mechanism. An implementation problem of this window-based scheme in large-scale networks is the significant control overhead associated with the flow of permits. The first approach is a partially decentralized control architecture that extends the centralized isarithmic scheme by means of an hierarchical zoning structure. An adaptive isarithmic controller is located in each zone with a distinct permit class and the zones interact through user traffic and management information flows. The decentralized architecture allows a substantial reduction of the permit flows and numerical results show that the network optimal operating point can be reached. Moreover, the level of management flows can be limited without deteriorating the network performance by using the approximate global information structure, based on mean delays. The second approach consists of decreasing the window size by letting one permit correspond to C credits. The control overhead is then reduced by a factor of C , the credit/permit ratio. Simulation results show that the network performance can even be improved compared to the centralized isarithmic scheme.