Network Quality Of Service (qos) Control

The problem that the paper wants to solve is QoS controlling. With the development of computer network, more and more voice, picture and video transmit through network instead of single data. Only best effort service is provided by traditional network, so that the congestion problem becomes serious. There are lots of methods to slove the network congestion, for example, widening network bandwith, restricting or deducing some operation flow, improving the performance of router. In summary, solving the problem of QoS is not only an urgent task, but also a complicated and big work.The paper's main work is discussing some effective methods of controlling QoS. This article discusses the combination of Integrated Service Model and Differentiated Service Model through the analysis of the two model. Then the topic is put forword: to modify the key algorithm of DiffServ—RED and modify the algorithm of Distributing Bandwidth Fairly in DPS. The paper discusses how to combine DiffServ and MPLS to realize flexible QoS.The emphysis of this paper is analyzing two QoS model: one is Integerated Serivce, for short, IntServ; the other is Differenciated Service, for short, DiffServ. The IntServ is usually used in the condition of Enterprise Network's Edge. RSVP (Resource Reservation Protocol is the rule of per flow between source station and destination station. The information of RSVP is in all over the network, requiring or reservating the resource. The IntServ concludes four components: Packet Attemper, Access Control, Sort System, Reservation Protocol. The DiffServ is usually used in the core of large network, what routers of which save is not the information and state of per stream, but of stream aggregate. The outer behavor is PHB(Per Hop Behavor), therefore, it decuces the burden of core node and assures the network strong and expansible. It's the main content of this paper to combine these two models and promote each other. The key technology and theory of this paper is QoS Models, Congestion Control theory, MPLS, and so on.Innovation of this paper is modifying the key algorithm of congestion avoidence inDiffServ—Random Early Detection: RED in the aspect of fairness and providing program in natural language and comparing the advantages and shortcomings to other algorithms. The paper also modifies the algorithm of Distributing Bandwidth Fairly in DPS and analyzes its adapted environment and usage.