- Alternative spelling of 'pon. Contraction of upon
pon - Computer Definition
A fiber optic local loop network without active electronics, such as repeaters or multiplexers. A PON uses inexpensive passive optical splitters and couplers that require no electrical power and that perform no processes other than to split downstream signals and combine upstream signals. PON standards originated as a set of Physical Layer (Layer 1) specifications developed by an international consortium of vendors. The resulting Full Service Access Network (FSAN) initiative for an ATM-based Passive Optical Network (APON) scheme, was ratified by the ITU-T within the G.983.1 standard. Elements of a PON comprise an Optical Line Terminal (OLT), an Optical Network Terminal (ONT), an Optical Network Unit (ONU), a passive splitter, and optical fiber.
(Passive Optical Network) An optical point-to-multipoint access network. There are no optical repeaters or other active devices in a PON, hence the name "passive." PONs are designed for local loop transmission rather than long distance and serve to bring fiber closer to the customer in order to obtain higher speed. PONs began in 1995 when a group of telecom providers organized the Full Service Access Network group (see FSAN). An optical line terminal (OLT) device resides in the telco central office or cable company head end. It generates or passes on SONET and DWDM signals via fiber to an optical network unit (ONU) in the field. The ONU provides the optical to electrical (O-E) and electrical to optical (E-O) conversion between the fiber and the copper wires that reach homes and offices in a "fiber to the curb" (FTTC) or "fiber to the neighborhood" (FTTN) scenario. When the optical line goes directly into the building for "fiber to the home" (FTTH), an optical network terminal (ONT) is used to terminate the fiber. Fiber to the home is also called "fiber to the premises" (FTTP). APON, BPON, EPON and GPON APON (ATM PON) was the first passive optical network and uses ATM for transport. BPON (Broadband PON) includes APON, Ethernet and video transports. GPON (Gigabit PON), which uses the SONET GPF frame, is designed to be efficient for packets as well as TDM. BPON and GPON are the ITU-T G.983 and G.984 standards respectively. EPON is the IEEE Ethernet standard for PONs.