Feedback control of congestion in packet switching networks.

Abstract

Congestion control is among the major functions an operational network needs to provide. In this dissertation, a novel architecture for congestion control in packet switching networks has been developed and design techniques for congestion controllers have been derived. The architecture is based on local congestion controllers associated with each link. The controller of each link calculates, using only local information, the traffic admission rate which is periodically adjusted up or down as the link's buffer falls below or rises above a certain target level. The traffic admission rates are delivered to the sources and are used to throttle the input rate so that the traffic admitted for transmission matches the network resources. The whole system is, therefore, represented as a set of local controllers interacting through the network. In the framework of this architecture, we have developed the following: (1) The structure and the order of the controller associated with each link. (2) Methods for choosing the controller gains that ensure good dynamic behavior of the network. (3) Extensions to the case of multiple congestion. (4) Design examples and numerical simulations for the performance evaluation of the resulting system. The main contribution of this dissertation is the design methodology that leads to a control architecture which ensures a stable, congestion-free operation of the network with acceptable fairness properties. No similar results are available in the literature.