July 15, 2019
EPON technology introduction
EPON, also known as GEPON, was proposed by the EFM (Ethernet in the First Mile) working group established in November 2000 and is regulated in the IEEE 802.3ah standard. Its work focuses on the EPON MAC protocol.that is minimally augment the Ethernet MAC protocol。
It uses Ethernet as the carrier on the PON layer and uplinks to send data streams in burst Ethernet packets. The core part of EPON is the PON optical transmission/reception module. The implementation scheme is to restore the physical layer PON of APON based on the structure similar to APON and G.983, and replace the ATM technology as the data link with Ethernet technology. Layer protocols form a new combined EPON that can provide greater bandwidth, lower cost, and greater business capabilities.
EPON provides up-and-down symmetrical 1.25 Gbps line transmission rates (and 10 Gbps downlink rate systems are also under investigation). Although EPON uses Ethernet encapsulation, it is very suitable for carrying IP services. At the time, IEEE originally formulated 802.3ah to access IP data services, and did not consider the special requirements of TDM service access for clock synchronization, delay and jitter. Therefore, the standard Ethernet encapsulation method adopted by EPON also brings a fatal shortcoming, that is, it is difficult to carry TDM services such as voice or circuit type data lines, and it is difficult to meet carrier-class QoS requirements.After that, although the TDM over Ethernet technology has been actively researched at home and abroad, China has also developed the communication industry standard "Access Network Technical Requirements - Ethernet-based Passive Optical Network (EPON)", and many EPON vendors The IEEE standard has been expanded to provide technical innovations in EPON carrying TDM services and voice services, such as providing data services and using reserved bandwidth to provide voice services, and many EPON vendors have also designed new ones. The MAC mechanism adds new hardware and software, but it is quite difficult to fully meet the strict QoS requirements of TDM services, which brings certain restrictions to the application of EPON.