Optical fiber transceiver is a very cost-effective and flexible device. The common use is to convert electrical signals in twisted pairs into optical signals. It is generally used in Ethernet copper cables that cannot be covered and must use optical fibers to extend the transmission distance. In the actual network environment, it also plays a huge role in helping to connect the last mile of fiber optic lines to the metropolitan area network and the outer network. A switch is a network device used for electrical (optical) signal forwarding, and plays a central role in the mutual communication between wired network devices (such as computers, printers, computers, etc.)