Research On Packet Forwarding And Traffic Control System Based On Network Flow Engine Card

The sustained and rapid development of the Internet has brought the continuous increasement in network bandwidth and the emergence of various complicated services, especially multimedia services, resulting in the requirements of the network interconnection equipment to possess the capability of line-rate packet processing and to implement some quality of service(Qo S) guarantee mechanisms. As a new product of network processors, the network flow engine(NFE) card can process network data at high speed, and can be used to develop various network applications using C instead of microcode, thereby reducing the development difficulty and shortening the development cycle. With queue management and queue scheduling as the core, the traffic control technology is not only an important way to achieve network Qo S guarantee, but also a significant research field. Therefore, the research on packet forwarding and traffic control system based on NFE is of high application value.Supported by the National High-Tech Development Project(863 project), the test and simulation of next generation converged satellite and terrestrial broadband communication network, this dissertation studies the IP packet forwarding and network traffic control system based on NFE3240. Firstly, the procedure of packet forwarding is outlined, and several common longest prefix matching(LPM) routing lookup algorithms are compared and analyzed on the basis of the introduction to the effects of IP address structure change on routing lookup. Meanwhile, the key technologies of traffic control, including packet classification, queue management and queue scheduling, are introduced based on existing Internet Qo S models, and the introduction to several major algorithms about active queue management and queue scheduling are put on emphasis.Secondly, the functions of the packet forwarding and traffic control system discussed in this dissertation are elaborated, and main features of the NFE3240 hardware and network flow manager(NFM) software development platforms are presented, with the emphasis on the illustration of their classification function based on ternary content addressable memory(TCAM) and flow state table(FST). Combined the system functions and platform features, the overall design of the system implementation scheme comprised of five modules is accomplished, and each module is specifically designedand implemented. For the routing table update and lookup module, an implementation scheme of multi-branch tree with path compression based on the unique prefix is designed. In the packet classification module, a two-level classification scheme is designed, which can take full advantages of the platform classification function. The weighted random early detection(WRED) and deficit round robin(DRR) algorithms are adopted in the queue management and scheduling module.Finally, a brief introduction to the NFM setup and development environment test is given, and the functions of the packet forwarding and traffic control system implemented in this dissertation are tested and verified. Through various test schemes designed, we have tested the system functions of both packet forwarding and traffic control, and thus the capabilities of high-speed packet forwarding and some degree of traffic control are verified.