Research On The Packet Forwarding And Traffic Control Modules Based On Network Processor

With the continuous rapid development of Internet, the network bandwidth is growing constantly and the types of network services are increasing. However, different services have different requirements for quality of service(Qo S), and the traffic control technique based on queue management and scheduling is an important way to guarantee Qo S. The traffic control technique can meet user’s requirements for throughput, delay, jitter and so on. Because of the advantages of programmability, short development cycle and high processing performance, network processor platform is especially designed for network processing. Therefore, it is of great application value to study and implement packet forwarding and traffic control modules based on network processor.Supported by the National High-Tech Development Project(863 project), the test and simulation of next generation converged satellite and terrestrial broadband communication networks, this dissertation has performed the design and implementation of packet forwarding and traffic control modules based on IXP2350 network processor. The basic principles of packet forwarding and traffic control are described. Several typical longest prefix match(LPM) search methods are compared, and their time and space complexity are discussed. In addition, the dissertation provides an overview of the traffic control techniques, and particularly summarizes the key technologies of data flow classification, queue management and queue scheduling used in the differentiated services(Diff Serv) architecture.The dissertation presents the overall function of the packet forwarding and traffic control system, and gives an overview of the network processor hardware platform and its portable software development framework. Then we study the whole design and implementation of the system and propose the scheme of packet forwarding and traffic control based on Diff Serv. And we also accomplish multiple modules of the software development in data plane, including the link status detection module, packet forwarding module and traffic control module. The packet forwarding module uses the longest prefix match search algorithm, and the traffic control module controls traffic rate by setting up different packet loss rates for different categories of services. Aimed at eliminating partially the disadvantages that deficit weighted round robin(DWRR) algorithm has low throughput and poor delay jitter in particular scenario, an improved deficit weighted round robin(IDWRR) queue scheduling algorithm is proposed. For two scenarios,all queues contain packets with its length random uniformly distributed and a certain queue contains consecutive short packets, we evaluate the throughput and delay jitter performance of the proposed improved algorithm. The simulation results show that the proposed algorithm, to a certain extent, can improve the performance of original algorithm in throughput and delay jitter.Finally, this dissertation introduces the Workbench development tool, and gives two test scenarios and their specific building steps. Meanwhile, a detailed description of the test process of the packet forwarding and traffic control is given, and the results primarily validate that the design and implementation of the software modules are correct. Besides, we conclude the dissertation and present the arrangement for the next work.