We consider large buffer asymptotics for feed-forward networks of discrete-time queues with deterministic service rate shared by multiple classes of streams. First we review the concept of effective bandwidths for traffic streams subject to a tail constraints on the buffer occupancy. Next, we discuss the effective bandwidth of the departure process of such a queue, proving that in fact the effective bandwidth of the output is at worst equal to that of the input, and depending on the service rate, strictly less than that of the input. We then define the notion of a decoupling bandwidth guaranteeing that asymptotics within the network are decoupled. These results provide a framework for call admission schemes which are sensitive to constraints on the tail distribution of the workload in buffers or approximate cell loss probabilities. Our results require relatively weak assumptions on both the traffic streams and service policies. We consider the problem of "optimal" traffic shaping (via buffering) subject to a loss or delay constraint. Finally, we discuss our results in the context of resource management for ATM networks.




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