What are Passive Optical Network (PON) and Active Optical Network (AON)?

- Nov 10, 2020-

PON

Passive optical network (PON) is mainly composed of the optical line terminal (OLT) at the central office and the optical network unit (ONU) at the user end. It is a point-to-multipoint network with broadcast mode in the downlink and time division multiple access in the uplink It can flexibly compose tree-shaped, star-shaped, bus-shaped and other topological structures. Only a simple optical splitter needs to be installed at the optical branch point. Therefore, it has the advantages of saving optical cable resources, bandwidth resource sharing, saving equipment room investment, and building The advantages of fast network speed and low comprehensive network construction cost.

Passive optical network (PON) can also be subdivided into broadband passive optical network (BPON), gigabit passive optical network (GPON) and Ethernet passive optical network (EPON). Among them, gigabit passive optical network ( GPON) and Ethernet Passive Optical Network (EPON) are more common.

GPON

Gigabit Passive Optical Network (GPON) is the latest passive optical network (PON) technology. Its downstream rate can reach 2.48 Mbps, which can be shared by up to 64 end users. In addition, Gigabit Passive Optical Network (GPON) can also support multi-source protocols and comply with Ethernet, TDM and ATM standards, so as to provide traditional business services, such as TDM-based voice and leased lines, without changing the user equipment. 

 

Data capacity

The downlink rate is 1.24 Mbps or 2.48 Mbps, and the uplink rate is 622 Mbps or 1.24 Gbps

Number of end users

If the distance between the optical line terminal (OLT) and the optical network unit (ONU) is 20 km, it can support 32 users;

If the distance is between 12-15 km, 64 users can be supported; if the distance is 30 km, only 16 users can be supported.

Supported protocol

Ethernet, ATM and TDM


EPON

Ethernet Passive Optical Network (EPON) is a passive optical network (PON) technology based on Ethernet. It uses passive optical network (PON) technology at the physical layer, and uses the Ethernet protocol at the link layer to utilize passive The topological structure of the optical network (PON) realizes the access of Ethernet. Therefore, Ethernet Passive Optical Network (EPON) combines the advantages of passive optical network (PON) technology and Ethernet technology: low cost, high bandwidth, strong scalability, flexible and fast service reorganization, and compatibility with existing Ethernet Compatibility, etc.


Data capacity

Upstream and downstream rates are both 1.25Gbps

Number of end users

When the distance between the optical line terminal (OLT) and the optical network unit (ONU) is 20 km, a maximum of 32 users are supported

Supported protocol

Ethernet


AON

Active optical transmission equipment (photoelectric conversion equipment, active optoelectronic devices, and optical fibers, etc.) is also deployed between the central office end and the user end of the active optical network (AON), which can be divided into PDH-based and SDH-based active optical transmission equipment. Network (AON), the active optical network (AON) based on SDH is commonly used at present. It has an access rate of 155Mbs or 622Mbs, and the transmission distance can reach 70 km without a repeater. Different from the passive optical network (PON), the signal received by the optical network unit (ONU) in the active optical network (AON) is the signal after the optical-electric-optical conversion of the active device. The active optical network (AON) technology is very mature, but its deployment cost is higher than that of the passive optical network (PON).

Conclusion

Passive optical network (PON) and active optical network (AON) have their own characteristics. At present, passive optical network (PON) is more common in fiber to the home (FTTH) network.