Understand the difference between the role of industrial-grade ONU and OLT?

Optical access network (OAN) refers to the use of optical fiber as the main transmission medium to realize the information transmission function of the access network. It is connected to the service node through the optical line terminal (OLT), and connected to the user through the optical network unit (industrial ONU). Optical fiber access, the network includes remote equipment-optical network unit and central office equipment-optical line terminal, which are connected by transmission equipment. The main components of the system are OLT and remote industrial-grade ONU. They complete the conversion of signaling protocols from the service node interface (SNI) to the user network interface (UNI) in the entire access network. The access device itself also has networking capabilities and can form various forms of network topology. At the same time, the access equipment also has the functions of local maintenance and remote centralized monitoring, forming a maintenance management network through transparent optical transmission, and bringing it into the network management center for unified management through the corresponding network management protocol.

The role of the OLT is to provide an interface between the access network and the local switch, and communicate with the optical network unit on the user side through optical transmission. It completely separates the switching function of the switch from user access. The optical line terminal provides maintenance and monitoring of itself and the user end. It can be directly placed at the exchange office end together with the local exchange or at the remote end.

The role of the industrial-grade ONU is to provide a user-side interface for the access network. It can be connected to a variety of user terminals, and at the same time has a photoelectric conversion function and corresponding maintenance and monitoring functions. The main function of the ONU is to terminate the optical fiber from the OLT, process the optical signal and provide service interfaces for multiple small businesses, business users and residential users. The network end of the industrial-grade ONU is an optical interface, and its user end is an electrical interface. Therefore, ONU has optical/electrical and electric/optical conversion functions. It also has the functions of digital/analog and analog/digital conversion of dialogue. The ONU is usually placed close to the user, and its location has great flexibility.

OAN is divided into active optical network (AON, Active Optical Network) and passive optical network (PON, Passive Optica Optical Network) in terms of system distribution.