ONU (Optical Network Unit) ， ONU is divided into active optical network unit and passive optical network unit. Generally, the equipment equipped with network monitoring including optical receiver, uplink optical transmitter and multiple bridge amplifiers is called optical node. The PON uses a single fiber to connect to the OLT, which then connects to the ONU.
PON is a typical passive optical fiber network, which means that (in the optical distribution network) does not contain any electronic devices and electronic power supplies, and ODN is all composed of passive devices such as optical splitters (Splitter) source electronics. A passive optical network consists of an optical line terminal (OLT) installed in a central control station, and a number of supporting optical network units (ONUs) installed in the user's premises.
Different functions
OLT: opticalline terminal (optical line terminal), a terminal device used to connect the optical fiber trunk line; the ONU has two functions: selectively receiving the broadcast sent by the OLT, and responding to the OLT if the data needs to be received; The Ethernet data to be sent is collected and buffered, and the buffered data is sent to the OLT according to the allocated sending window.
EPON (Ethernet Passive Optical Network), which has the characteristics of saving fiber resources and being transparent to network protocols, EPON uses a single fiber to connect to the OLT, and then the OLT is connected to the ONU.
The connection of "OLT", "ONU" and "PON".
Both the OLT and the ONU are part of the PON architecture. The OLT is the optical line terminal and is the central office equipment of telecommunications. Generally, it is directly connected to the BRAS. The ONU is the optical network unit. Under one OLT, multiple ONUs can be connected through the optical splitter. It is fiber-to-the-home (FTTH) when it reaches the user's home, and light-to-the-building (FTTB) when it is placed in a building. ONU is a device, PON is a technology or architecture.
