EPON is the best combination of several technology and network structure. EPON uses multipoint structure, passive optical transmission, offers a variety of services over Ethernet. At present, IP/Ethernet applications accounted for more than 95% of the entire LAN communication, EPON since the economic and efficient use of the above-described structure, will become an end-user access network connecting the most efficient communication method.

EPON without any complex agreement, the optical signal can be accurately delivered to the end user, the data from the end user can also be transmitted to a central network concentrated. At the physical layer, EPON Ethernet PHY 1000BASE use, while at the PON transmission mechanism to control and optimize the burst data communication between the ONU and OLT and real-time TDM traffic through the newly added MAC control commands. In the second layer protocol, EPON mature full-duplex Ethernet technology. Using TDM, since the ONU transmits data packets in their time slots, so there is no collision, no CDMA/CD, to make full use of bandwidth. In addition, EP0N by implementing 802.1p in the MAC layer to provide similar APON QoS.

A typical system consists of Ethernet over PON OLT, ONU, POS components. OLT (Optical Line Terminal) at the center of the room, ONU (Optical Network Unit) placed near or in connection with the network interface unit into one. POS (Passive Optical Splitter) is a passive connection OLT and ONU equipment, its function is to distribute downstream data and centralized uplink data. OLT is both a switch or router, is a multi-service provisioning platform that provides for passive optical network optical interface. According to the trend towards Ethernet metro and wide-area development, OLT will provide multiple Gbit/s and 10Gbit/s Ethernet interface, support for WDM transmission. OLT also supports connections ATM, FR and OC3/12/48/192 and other rates of SONET. If you need to support traditional TDM voice of ordinary telephone lines (POTS) and other types of communications TDM (T1/E1) can be multiplexed onto attachment interface. OLT addition to providing network access to centralized and function, but also can assign different bandwidth requirements of the user QoS / SLA and network security and management configurations. OLT can be configured as required multiple OLT (Optical Line Card), OLC is connected with a plurality of ONU through POS, POS is a simple device, it does not need power supply, can be placed around the clock environment, the general rate of a sub-line POS 8, 16 or 32, and can be connected in multiple stages. In EPON, OLT to ONU distance between up to 20km, if you use fiber amplifier (active repeaters), the distance can be extended.

EPON ONU used in Ethernet protocol technology mature and the economy, in the ONU bandwidth and high bandwidth to achieve a low-cost Ethernet second layer and the third layer switching capabilities. This type of ONU can provide high bandwidth shared by stacking a plurality of end users. Because both use the Ethernet protocol, in the process of communication, there is no need protocol conversion, ONU transparent transmission of user data. ONU also supports other traditional TDM protocol, and will not increase the complexity of the design and operation. ONU in higher bandwidth, and offers a wide range of Ethernet interfaces and multiple T1/E1 interfaces. Of course, for fiber to the home (FTTH) access mode, ONU and NIU can be integrated in a single device, without switching function, which can allocate the required bandwidth to the end user at very low cost.