Optimal buffer management for shared buffer ATM switches.

摘要

The Quality of Service parameters like cell loss probability, average delay, and jitter, that are guaranteed in ATM networks, are affected by the architecture of and resource management within network switches. In this thesis, we study the problem of allocation of buffers amongst cells of different output ports in a shared buffer ATM switch, with the aim of minimizing the total cell loss in the system.;The analysis proves that for a 2 x 2 switch with either iid Bernoulli or correlated D-BMAP arrival processes, when the buffer management policy is allowed to push out cells, the optimal algorithm is of the threshold type; i.e. there exist unique thresholds for the length of an output queue above which the cells of that output are pushed out in favor of cells of the other output. We provide a numerical technique to evaluate these thresholds when the probability distribution function of the arrival process is known; we also provide a dynamic algorithm, along with proof of its convergence for the case that it is not known.;For the switch with N input and output ports, we perform simulations with various Pushout policies with static as well as dynamically determined thresholds. These simulations reveal that the total cell loss probability of the system does not vary much with the value of the thresholds used. However, the individual performance (cell loss) of an output port is isolated from the fluctuations in loading of other ports.