APON

APON is the abbreviation of ATM PON. ATM is a transmission protocol based on cells. In recent years, it has been more and more widely used in the access network to provide various services such as video broadcasting, distance education, and data communication. ATM technology can provide dynamic bandwidth allocation for the access network, which is more suitable for the needs of broadband services.

The network topology of a typical APON system is a star structure. As a typical point-to-multipoint application, it is more suitable for future system upgrades and expansions.

The main difference between EPON and APON is in the frame structure (the frame structure, frame period, length and packaging method of EPON and APON are all different). The main technical difference is: EPON data transmission is carried out in variable-length packets, The longest is 1518 bytes; while APON data is mainly transmitted in ATM cells with a fixed length of 53 bytes.

APON proponents claim that their systems have a fixed-length frame structure for faster and more efficient synchronization, while IP-based EPON schemes never know how long a packet is and must be hard-cut and sorted by smaller length regrouped. This is because the maximum length of an IP packet specified by the Internet is 65535 bytes, while the maximum length of a packet specified by the EPON protocol is 1518 bytes.

EPON proponents argue that carrying IP traffic with APON is difficult and inefficient. APON packets must be cut into 48-byte segments, and a 5-byte header must be added to each segment, so this processing method is time-consuming, complicated, wastes bandwidth, and adds extra cost.

At the beginning of this century, with the development of Internet technology and other communication technologies, APON also exposed the weakness of relatively low bandwidth. From the implementation point of view of various manufacturers, ATM packaging is basically abandoned.

APON technology has completed its historical mission as a practical deployment method, but as the originator of PON technology, the core technical ideas are still applied in various PON technologies.