Congestion Control And Scalable Multicast Routing In IP Networks

Internet has been developed into the basic of today's social life. People are expecting more and more capabilities such as performance,content and safety from network. 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 causes the dropping of packets or the jitteriness of transport,and even pervades to collapse the network. With the development of Internet based business and applications,Quality of Service (QoS) is required and Internet is expected to support the QoS. Congestion control is the base of QoS and routing technology can give good support to the QoS system.No matter how the network is,it is necessary to carry out the congestion control. The prevail model of congestion control research is that firstly propose a scheme based on experience and intuition,and then verify and improve it through simulations and experiments,and main attention is paid on the functions of the end systems. We analysis the congestion control system as a close loop system and take the router as the feedback controller. So the role of queue management is emphasized and new active queue management algorithms are designed.Common QoS-aware dynamic multicast routing algorithms have the same problems such as complexity,long joining latency for new members,heavy control message overhead,which cause the poor scalability. It is hard to design an algorithm that is suit for large multicast group size. The keys are how to avoid the algorithm's dependency of the networks' topologies and how to calculate the connecting routing for the new members efficiently. We give out our solutions in our research.We take both the active queue management algorithm and the QoS-aware dynamic multicast routing algorithm as our topics. They are both related to the task of QoS guarantee in the network. Active queue management is the transport control problem in the end-to-end system,routing is about resource allocation and assignment which can decide directly the QoS of certain applications.The main contents and contributions are listed below:(1) Analysis of the QoS guarantee system in the IP network,which includes the protocols,standards and polices.(2) Discuss the structure of the end-to-end congestion control schemes with active queue management (AQM) in IP network from the control-theoretic point of view. Give out a method to estimate the maximum drop probability of RED (Pmax) in view of TCP sources' maximum window limit. And propose a fuzzy logic based AQM which can improve the robustness of the control algorithms. Give out the detailed simulations.( 3 ) Study of the network model and the QoS restrictions of QoS-aware multicast routing problem. Summarize the routing algorithms and protocols. Analysis the shortcomings and the QoS support abilities of currently used multicast protocols.(4 ) Propose a QoS-aware dynamic multicast routing algorithm named TADMR. Most of aimless searching in some similar algorithms can be avoided. TADMR can be used to construct low cost tree similar to optimal greedy strategy with adaptation to the topology of network. Control overhead and access latency can also be reduced greatly,so it scales well. Simulations results proved these.(5) Study the routing control capability of RSVP protocol and it's relation with the QoS problem. Propose a scheme that use RSVP as the routing message protocol of TADMR.