ONU could be connected by various methods and cable types, like twisted-pair copper wire, coaxial cable, optical fiber, or through Wi-Fi.Įnd-user devices may also be referred to as the optical network terminal (ONT). OLT supports bandwidth allocation that allows making smooth delivery of data float to the OLT, which usually arrives in bursts from the customer. Grooming is the process that optimizes and reorganizes the data stream so it would be delivered more efficiently. Furthermore, ONU can send, aggregate, and groom different types of data coming from the customer and send it upstream to the OLT. In general, there is a distance or other access network between ONU and end user's premises. These electrical signals are then sent to individual subscribers. ONU converts optical signals transmitted via fibers to electrical signals. Optical Network Unit (ONU) / Optical Network Terminal (ONT) The OLT has two float directions: upstream (getting distributing different types of data and voice traffic from users) and downstream (getting data, voice, and video traffic from the metro network or from a long-haul network and send it to all ONT modules on the ODN.) The maximum distance supported for transmitting across the ODN is 20 km. In these parts, PON card and power supply support hot-swap while another module is built inside. In general, OLT equipment contains rack, CSM (Control and Switch Module), ELM (EPON Link Module, PON card), redundancy protection -48V DC power supply modules or one 110/220V AC power supply module, and fans. The primary function of the OLT is to convert, frame, and transmit signals for the PON network and to coordinate the optical network terminals multiplexing for the shared upstream transmission. OLT is the starting point for the passive optical network, which is connected to a core switch through Ethernet cables. In addition, the optical distribution network (ODN) is also used during the transmission between OLT and ONU/ONT. In a Gigabit Ethernet Passive Optical Network (GEPON) system, there are an optical line terminal (OLT) at the service provider's central office and a number of optical network units (ONUs) or optical network terminals (ONTs) near end users, as well as the optical splitter (SPL).

Ont optical network terminal