Optimal Buffer and Bandwidth Allocation for Multiplexed On/Off Sources

We consider a single node which multiplexes a large number of traffic sources. We are concerned with the amount of buffer and bandwidth that should be allocated to a class of i.i.d. on/off fluid flows. We impose a maximum overflow probability on the class, and assume that the aggregate flow can be modelled using effective bandwidth. Unlike previous approaches which assume that the total buffer allocated to the class is either constant or linearly proportional to the number of sources, we determine the minimum cost allocation given a cost per unit of each resource. We find that the optimal bandwidth allocation above the mean rate and the optimal buffer allocation are both proportional to the square root of the number of sources. Correspondingly, we find that the excess cost incurred by a fixed buffer allocation or by linear buffer allocations is proportional to the square of the percentage difference between the assumed number of sources and the actual number of sources and to the square root of the number of sources.