The Design, Based On The Intel Ixa Gigabit Ethernet Router

The rapid growth of the Internet has prompted increasing needs for the router that is one of the Internet infrastructures. The new generation of router will not only forward packets at high speed, but also possess proper security to protect the network. The Intel IXA, through powerful processor and flexible development tools, provides the best solution for such network applications. This paper practices design a gigabit Ethernet router with some security features based on the study of the IXA. The paper consists of the following aspects:Chapter 1 describes the background of the design. Analyzes the changing of the network traffic pattern, and simply describes the hardware platform of the design - the IXP1200 Ethernet Evaluation System. Then describes the core of the IXA - the IXP1200 network processor in the chapter 2. This chapter summarizes the features of the IXP1200, analyzes some technology and new concepts introduced in the IXP1200, and describes each function unit in the IXP1200 in detail.Chapter 3 serves as the system design. Firstly, describes the three main functions of the system: building the basic data path, packet filtering, and network address transition (NAT) as well as the task partitioning of the StrongARM Core and microengines. Then describes the StrongARM software structure and microengine data flow. Lastly, describes the important data structures and the usage of the three type memories.A series of basic functions are performed in the chapter 4, includes microengine Initialization, packet receive processing, exception process, MAC and IP header processing, IP forwarding, and packet transmit processing, etc. These functions build a basic data path for the whole system. The later functions (as well as the functions not implemented in this design) can be expanded on this basic data path.Chapter 5 and chapter 6 implements some security functions based on the basic data path implemented in the chapter 4, they are packet filtering and network address transition (NAT). Packet filtering is an efficient security method that is commonly used in router and firewall. NAT is ashort-term solution for the IP address shortage, and not a security method essentially, but it can "hide" the inside network actually. The two chapters describe the security features, mechanism, and the implements on the IXP1200.The ending of the paper summarizes the functions implemented and not implemented in the design, and arranges the things to do.Some information in the chapter 1 and chapter 2 refers to "The IXP1200 Hardware Manual", the design portion of the paper is accomplished by myself.