study on ATM multiplexing and threshold-based connection admission control in connection-oriented packet networks

The research reported in this dissertation studies ATM multiplexing and connection admission control schemes for traffic management in connection-oriented packet networks. A new threshold-based connection admission control scheme is proposed and analyzed. The scheme uses effective bandwidth to make decision whether to accept or reject the connection request. This threshold specified effective-bandwidth method is first simulated on a simple 4-node connection-oriented packet network model, and then extended to a more complex 8-node network model under a variety of environments. To reduce the cell-loss ratio when the arrival rates of the connection requests are large, the dynamic effective bandwidth mechanism is proposed and relevant simulations are addressed on the two network models. The traffic used in the simulation is a multiplexed stream of cells from video, voice and data sources, which is typical in ATM environments. The multiplexed traffic is generated using a discrete event scheduling method. The simulation programs for the 4-node network model and for the 8-node network model are verified by the theoretical values of the blocking probabilities of the connection requests, and Little's Theorem. Simulations on the two network models show similar results. Pertinent to a network that supplying several service categories, the threshold-based connection admission control is shown to affect the blocking probabilities of each type of traffic. In some environments, having a threshold is advantageous over the case without a threshold in terms of cell-loss ratio, cell transfer delay and power (throughput divided by cell transfer delay). The simulation results also show that the dynamic effective bandwidth based method helps to reduce the cell-loss ratio significantly when the arrival rates of the connection requests are large.