Switch is a collective term for technologies that send information to corresponding routers manual or automatic according to the needs of the two ends of the communications. The switches can be divided into WAN switches and LAN switches according to different working positions. The wide-area switch performs information exchange functions in a communication system which is applied at the data link layer. Usually switch has multiple ports so sometimes called multi-port bridge, each of which has a bridging function, and can be connected to a LAN or a high-performance server or workstation. A network switch is a device that expands the network and can provide more connection ports in a sub-network in order to connect more computers. With the development of the communications industry and the advancement of the national economy informazation, the network switch market is steadily rising. It is cost-effective, highly flexible, relatively simple, and easy to implement. Ethernet technology has became the most important LAN networking technology today, and network switches have became the most popular switches.