Traffic shaping at a network node: theory, optimum design, admission control

This paper develops a framework of traffic shaping which has the goal of increasing the nodal connection-carrying capacity. The shaping filters are designed to interwork with statistical multiplexers which use FIFO buffers. Differences in delay tolerances between traffic classes are exploited to shape and smooth the less delay sensitive traffic. The source model used in the analysis is asynchronous, worst-case subject to dual leaky bucket regulation, where the asynchrony is due to the assumption of independent sources. This, together with the allowance of small loss probabilities, makes statistical multiplexing feasible. We require the shapers to be lossless so that losses, if any, occur only at the multiplexer. We obtain the optimal design of the shaper such that a given delay tolerance for the connection is satisfied. For purposes of admission control we obtain the admissible region of combinations of sources of various types such that the QoS requirements in loss and delay are satisfied. By examining the regions obtained with and without shaping we quantify the capacity gain from shaping. Our numerical results show that the gain can be substantial.