Active optical network central office equipment (CE) and remote equipment (RE) connected via active optical transmission equipment. Transmission technology is the backbone network SDH and PDH technologies have been widely adopted, but the main SDH technology. Remote device mainly to complete the collection business, interface adapter, multiplexing and transmission. Central office equipment mainly to complete the interface adapter, multiplexing and transmission. In addition, the central office equipment to the network element management system also provides network management interface. In the actual construction of the access network, active optical network topology is typically star or ring. Active optical network technology has the following characteristics: