Active Queue Management And Multicast Routing Algorithm. Ip Qos

Internet has been developed into the basic of today's social life with the era of information. At the same time, with the increaseing demands of distributed multimedia applications and the development of Internet based business and applications, people request network communication has a high level quality. However, the main kind of service is still'Best Effort'in the Internet. All packets are treated equally. There lacks of efficient queue management. Congestion happens here and there between whiles, which decend the capability of network, causes the dropping of packets or the jitteriness of transport. Many international organizations, communication equipment producers and service providers are researching and implementing the way to improve IP quality of service (IP QoS). The mechanism of active queue management is the base of QoS and multicast routing can give good support to the QoS system. Now this two aspects of IP QoS has became the focus of IP network researching field.This dissertation concentrates on researching active queue management algorithms and multicast routing algorithms with QoS constraints, proposes several modified active queue management algorithms and effective, practical QoS multicast routing. The main achievements in this paper are as follows:(1) Propose a DRED (Dynamic Random Early Detection) algorithm by regulating the operating parameters based on statistical features of networks. DRED adjust the value of Maxp and the control strength of congestion by the active drop rate in order to adapt to the change of network state effectively;At the same time, DRED adjust the drop rate two powers according the length of queue to make the drop rate sensitive to the length of queue, stabilize the queue and reduce the compulsive drop.The simulation results show that DRED has improved the adaptability and utilization of the RED algorithm, reduced the aggregate drop rate.(2) Propose a precision enhanced active queue management algorithm BLUE+, Which adjusted the parameters detin and detde of the BLUE algorithm dynamicly according to the average queue length and adjusted the value of Pmark according to the relation between the packet loss rate and the connection number in the TCP-friendly formula. Besides, it increased the updating speed of algorithm when the length of the queue decreases, which avoided a mass of packet losses. On this basis, this paper researched TCP congestion control method based on DiffServ of PEBLUE.