High level B-ISDN/ATM traffic management in real time

We study real time tra c management in the perspective of a four-level model of tra c variations: cells, bursts, sessions, and links. Our interest is focused on the two latter levels: Using virtual channels (VCs) and virtual paths (VPs) as the managed entities on the two levels respectively, we put forward a simple and robust strategy for tra c management in real time: All nodes simultaneously monitor o ered tra cs and forward the result to a network management centre (NMC); The NMC computes a new set of optimal VPs and compares the result to the existing network; If a change appears pro table, the necessary information is sent back to the nodes and the new design is implemented. Applying our strategy to control general networks subject to tra cs which in advance are known only as expectations, we develop simple methods for tra c observation, the optimal observation interval, a fast and e cient algorithm to compute VP networks, a test to determine whether to implement a new design in which costs related to lost tra c are compared to processing costs, and the optimal updating interval. Running our strategy in a simulator, we discover a considerable adaptivity, large savings in transmission capacity, and a performance far better than achieved by xed redesign according to forecasts. Finally we discuss limits to the range of variations within which our strategy can be applied. The present work applies both to networks using SDH/SONET and/or networks based on ATM, i.e. both to present public switched telephony networks and broadband integrated services digital networks, and is a summary and extension of earlier works within this area [3{9]. Keyword Codes: C.2.1, C.2.3