Design And Implementation Of Flow Control Technology On The FPGA Interface Card Of Distributed Router

The users and flow in information network increase rapidly with the development of network technology, which calls for faster transmission rate of the distributed router in network.IP packets in the FPGA (Field-Programmable Gate Array) interface card are forwarded mainly by the FPGA chip, which provides faster forwarding rate compare to CPU (Central Processing Unit).With the increasing service flow, there are not enough network resources to satisfy each user. However, flow control technology can ensure the reasonable application of network resources through controlling forwarding rate of distributed routers. Furthermore, hierarchical flow control technology is adopted to optimize network flow, which can schedule users and network traffic hierarchically to manage resources uniformly. Therefore, it is necessary to design and implement hierarchical and non-hierarchical flow control technology on distributed router. As the main technology of traffic controlling, CAR (Committed Access Rate) technology, which is divided into hierarchical and non-hierarchical CAR technology, is widely used.The thesis designs and implements hierarchical and non-hierarchical CAR technology on the FPGA interface card of distributed router.First of all, the thesis surveys the relative research, research status at home and abroad, and describes the research content of this paper.Secondly, the thesis introduces related flow control technology, including QoS (Quality of Service) technology, CAR technology and token bucket algorithm.Then, the thesis explains the internal structure of FPGA interface card and process of packets transmitting.After that, the thesis implements the function of hierarchical and non-hierarchical CAR technology on the FPGA interface card by detailed design and implementation of IQoS(Input QoS) module and CAR module.Finally, it is necessary to verify the function of non-hierarchical CAR technology and hierarchical CAR technology on the FPGA interface card by testing. Comparing average delay of packet transmission of the two scenarios indicates the hierarchical CAR technology has a higher average delay. the thesis have a conclusion that though hierarchical CAR technology can schedule users and network traffic hierarchically to manage resources uniformly, it leads to a larger average delay meanwhile. Therefore, hierarchical and non-hierarchical CAR technology have their own pros and cons, it is necessary to select appropriate CAR technology to control flow according to different needs of users.