Abstract
The purpose of a fair queueing scheme is to schedule packets from different traffic streams on an outgoing link (or port) such that the bandwidth of the outgoing link is shared among the traffic streams according to the service weights of the traffic streams. Several fair queueing schemes have been proposed in the literature. These schemes give each packet a tag at the arrival instant of the packet according to the service weight of the corresponding traffic stream. The packets are served in increasing order of their tags. However, if the service weight of a traffic stream is changed by the source or the congestion control mechanism. The new service weight can only be applied to tag newly arriving packets from the corresponding traffic stream. The expected effect of changing the service weight cannot be observed immediately. In this thesis, two fair queueing schemes which can adapt to time-variant service weights are proposed. The fair queueing schemes schedule packets according to the most updated service weights of the traffic streams. They can respond to changes of service weights immediately. The idea of the proposed fair queueing schemes is to postpone tagging a packet until it is to be scheduled. Thus, if there is any change of service weight, the new service weight can be employed to tag packets which are not yet transmitted. There-fore, the effect of changing service weight can be observed immediately.