Overview

A Passive Optical Network (PON) is a point-to-multipoint, Fiber-to-the-Premises (FTTP) network architecture in which unpowered optical splitters are used to enable a single optical feeder fiber to serve multiple premises. A PON consists of an Optical Line Termination (OLT) at the service provider's central office, head-end point-of-presence and a number of Optical Network Units (ONUs) near end-users.

A PON configuration reduces the amount of fiber and central office equipment required compared to point-to-point architectures. Downstream signals are broadcast to each premises sharing a fiber. Encryption is used to prevent eavesdropping. Upstream signals are combined using a multiple access protocol, such as Time Division Multiple Access (TDMA). The OLTs "range" the ONUs in order to provide time slot assignments for upstream communication.

Ethernet PON (EPON) has rapidly become the technology of choice for service providers worldwide as they deploy cutting-edge broadband access networks. In addition to the structural benefits of PON, EPON provides all the benefits of Ethernet as the network protocol. Carrier-class Ethernet is rapidly gaining widespread acceptance in the Service Provider market. Moreover, Ethernet is already entrenched in home and office networks. Given these trends, it is apparent why EPON is being used so prevalently in the access portion of the network.