Active Queue Management And Packet Scheduling In Differentiated Services Networks

Multimedia information is transported besides the data on theInteract with the development of multimedia technical, whereas it hasdifferent demand for quality of service, compared with the data.Differentiated Services architecture has recently become a good servicemodel for addressing QoS issues in IP networks. Besides best effortservice DiffServ provides two classical services, premium service andassured service. This dissertation mainly researches active queuemanagement and packet scheduling in assured service.This dissertation discusses some related work on active queuemanagement in assured service. Then a new active queue managementalgorithm-PIO based on the prediction of the arrival rate is presented. InPIO, the average arrival rate for IN packets and all packets in the nextinterval are predicted firstly. The PIO algorithm decides whether or not todrop the arriving packet according to the queue length for IN packets, thetotal queue length for all packets, the predicted arrival rate for IN packetsand all packets in the next interval. The simulation results indicate thatPIO compared with RIO improves the stabilization of queue and reducespacket loss ratio efficiently whether the network is under-subscribed orover-subscribed, while providing statistical assurance for the bandwidth.Subsequently, we describe some related work on packet schedulingin DiffServ networks, especially the probabilistie priority schedulingalgorithm. Then this dissertation also proposes a dynamic probabilisticpriority scheduling algorithm-DPP for the applications that have highrequirements for delay and packet logs ratio. DPP algorithm assigns theparameter p used to calculate scheduling probability according to thelength of queue for AF1 PHB, which can effectively solve the problem ofQoS degenerateness caused by the burst traffic. The simulation results indifferent environment indicate that DPP effectively diminishes the effecton average queueing delay caused by the burst and reduces the packetloss ratio.