Passive Optical Network - PON

A passive optical network (PON) is a fiber-optic telecommunications technology for delivering broadband network access to end-customers. Its architecture implements a point-to-multipoint topology, in which a single optical fiber serves multiple endpoints by using unpowered (passive) fiber optic splitters to divide the fiber bandwidth among multiple access points. Passive optical networks are often referred to as the "last mile" between an Internet service provider (ISP) and its customers.

PON is Passive Optical Network featured with one-to-multiple-point architecture. As shown in the following image, it comprises of Optical Line Terminal (OLT), Optical Network Unit and Passive Optical Splitter.

History of PON

The first Passive Optical Network (PON) activity was initiated by the FSAN group in the mid- 1990s. The initial standard covered 155 Mbps transmission based on ATM known as the APON/BPON standard. Later on, the standard enhanced to cover 622 Mbps.
In 2001, the IEEE started the development of an Ethernet based standard known as EPON. In 2001, the FSAN group started the development of a gigabit speed standard, i.e., GPON, to be ratified by the ITU-T.

PON History

PON Network Elements




An OLT provides the interface between a PON and a service provider's core network. These typically include:

- IP traffic over Fast Ethernet, Gigabit Ethernet, or 10 Gigabit Ethernet;
- Standard TDM interfaces such as SDH/SONET;
- ATM UNI at 155–622 Mbit/s.


- Network termination equipment (NTE), which receives the converged interface and outputs native service interfaces to the user, such as Ethernet and POTS.

A PON is a shared network, in that the OLT sends a single stream of downstream traffic that is seen by all ONUs. Each ONU reads the content of only those packets that are addressed to it. Encryption is used to prevent eavesdropping on downstream traffic.