Analysis Of RaQ Algorithm In Network Congestion Control

As distributed multimedia becomes more and more popular, the traditional IP network cannot afford the requirement of reliability, delay and jitter such applications. Such condition goes against the improvement of multimedia. Aiming at this fact, IETF raises a solution called DiffServ Model. This model can offer different service according to different traffic types, so it achieves QoS guarantee.Network congestion is an important issue of network QoS.With the development of multimedia application, network congestion can not be solved only depending on TCP congestion control which is implemented in source node. Router should actively play an important role in congestion control, so congestion control based on the middle node gradually becomes the main direction in current.The thesis introduces the concept and meaning of congestion and congestion control, also the concept and the analysis is introduced for IP QoS.Then the system and work mechanism of Diffserv is introduced. At last, the paper indicates that the AQM is important in the congestion control.This thesis make a deep study of DiffServ and the RaQ (Rate based and Queue based) algorithm. It partitions the PRI in AF PHB according to MTUS,then applies the RaQ algorithm in Diffserv and demonstrates that RaQ is better by simulations.On the based of the RaQ algorithm analysis, the thesis designs a kind of fuzzy controller based of RaQ algorithm, which can control the plant depending on the expert experience without the exact model of the network. Simulations shows that the algorithm can stabilize the queue length to the target value and has good stabilization and robustness and are more applicable to the complex and various network environments.The conclusion is drawn for the whole thesis, and the further research aspect is put forward.