PON

Stands for "Passive Optical Network." A PON is a telecommunications network that transmits data over fiber optic lines. It is "passive" since it uses unpowered splitters to route data sent from a central location to multiple destinations.

PONs are used by ISPs and NSPs as a cost-effective way to provide Internet access for customers. Since a PON is point-to-multipoint (P2MP) system, it provides a more efficient way to transmit data than a point-to-point network. The main transmission line can split off into 32 separate lines, which requires far less infrastructure than building direct lines to each destination.

The central location of a PON is also called the optical line terminal (OLT), while the individual destinations are called optical network units (ONUs). Lines that terminate outside buildings are called fiber-to-the-neighborhood (FTTH) or fiber-to-the-curb (FTTC). Lines that extend all the way to buildings are called fiber-to-the-building (FTTB), or fiber-to-the-home (FTTH).

While all PONs use optical cables and unpowered splitters, there are several different versions. Below is a list of different types of PONs.

1. APON - an early implementation (from the mid-1990s) that uses asynchronous transfer mode (ATM) to transfer data
2. BPON - the first "broadband" PON that supports data transfer rates of 622 Mbps, the same speed as an OC-12 (STM-4) line
3. GPON - a "gigabit-capable PON" that supports 2.488 Gbps downstream and 1.244 Gbps upstream; also called the ITU G.984 standard
4. EPON - the most popular PON implementation; transmits data as Ethernet frames at up to 10 Gbps downstream and upstream; also known as GEPON or the IEEE 802.3 standard