Epon technology is standardized by the IEEE802.3EFM Workgroup. June 2004, IEEE802.3EFM Working group released Epon Standard--ieee802.3AH (Merged into IEEE802.3-2005 Standard 2005). In this standard, the combination of Ethernet and PON technology, based on the architecture of passive optical network, a new Ethernet Data Link layer protocol is defined, which is applied to the EPON system (mainly optical interface) specification and expanded, in order to realize TDM access of Ethernet frames in the pon of point to multiple points. In addition, Epon defines a running, maintenance, and management (OAM) mechanism to implement the necessary operational management and maintenance functions.
In the physical layer, IEEE 802.3-2005 provides for single fiber dual-wavelength multiplexing (downlink 1490 nm, upstream 1310 nm), while defining $number base-px-10 u/d and $number base-px-20 u/d two pon optical interfaces, The maximum distance transfer between ten km and KM is supported respectively. In the physical coding layer, Epon system inherits the original standard of Gigabit Ethernet, using $number Line code and standard upper and lower line symmetric 1 Gbit data rate (line rate is 1. Gbit).
In the data link layer, the function of the multi-point Mac Control Protocol (Muti-point Kyoto, abbreviated as MPCP) is to realize point-to-point simulation in a point-to-point epon system, and support multiple Mac client layer entities in point to multi Point network. and support for additional Mac control functions. MPCP mainly deals with the discovery and registration of ONU, the allocation of uplink transfer resources between multiple ONU, dynamic bandwidth allocation (dynamism bandwidth allocation, abbreviated DBA), and the reporting of the ONU local congestion status of the statistic multiplexing.
Epon is based on Ethernet passive optical network, OLT and ONU between the Ethernet package, transmission is Ethernet frame structure, so epon is based on 802.3 frame format. Using its downlink broadcast mode, EPON defines broadcast llid (LLID=0XFF) as a single copy broadcast (SCB) channel for efficient transmission of downlink video broadcast/multicast services. Epon also provides an optional OAM feature that provides a mechanism for managing, testing, and diagnosing links to activated OAM functionality, such as remote fault indications and remote loopback control. In addition, IEEE 802.3-2005 also defines a specific mechanism extension to enable the extension of OAM functionality and remote management and control of other link layers or high-level applications.
Compared with Bpon and Gpon, Epon protocol is simple, and the specification of Optical transceiver module is low, so the system cost is lower. In addition, it inherits the strong scalability of Ethernet, the high efficiency of IP data service, and supports the integrated access of high-speed Internet, voice, IPTV, TDM and even CATV, and has good QoS guarantee and multicast business support capability. is one of the important alternative technologies for constructing high quality access network at present.