To understand EPON, GPON and other networks, we must first understand what is a PON network. PON is a passive optical network, which refers to the ODN (Optical Distribution Network) between the OLT (Optical Line Terminal) and the ONU (Optical Network Unit) without any active equipment and only uses optical fibers and passive components. PON mainly adopts a point-to-multipoint network structure and is the main technology to realize FTTB/FTTH.
PON technology contains a lot of content, and is constantly iteratively updated. Today’s GPON and EPON are technologies with different transmission modes and transmission standards developed in different periods.
EPON technology is standardized by the IEEE802.3 EFM working group. In June 2004, the IEEE802.3EFM working group released the EPON standard. In this standard, the Ethernet and PON technologies are combined, the PON technology is used at the physical layer, the Ethernet protocol is used at the data link layer, and the PON topology is used to realize Ethernet access. Therefore, it combines the advantages of PON technology and Ethernet technology: low cost, high bandwidth, strong scalability, compatibility with existing Ethernet, and easy management.
GPON is a new-generation broadband passive optical integrated access standard based on the ITU-TG.984.x standard. It has many advantages such as high bandwidth, high efficiency, large coverage, and rich user interfaces. GPON was proposed by the FSAN organization in September 2002. On this basis, ITU-T completed the formulation of ITU-T G.984.1 and G.984.2 in March 2003, and completed the standardization of G.984.3 in February 2004 and June 2004.The GPON standard was eventually formed.
The similarities between EPON and GPON:
They are all access technologies evolved from PON technology. The network structure is the same, all are OLT + optical splitter + user ONU devices connected together by optical fiber, and can carry the various services mentioned above.
The difference between EPON and GPON:
1. Different agreements
GPON is based on the combination of ATM technology + ITU-T transmission technology and PON technology.
EPON is based on the combination of Ethernet technology and PON technology, that is based on the IEEE series of protocols.
Briefly talk about two international organizations:
IEEE generally refers to the Institute of Electrical and Electronics Engineers, is headquartered in New York, USA. It is an international association of electronic technology and information science engineers and is currently the world’s largest non-profit professional technical society.
ITU Telecommunication Standardization Sector (ITU-T) is a branch under the management of the International Telecommunication Union that specializes in formulating telecommunications standards.
2. Different technical complexity
GPON can effectively support data packets and TDM streams in the original format, that is to say, it retains the traditional characteristics of ATM and the transmission of TDM data streams in the telecommunication transmission network, so the technical implementation is more complicated, and the conversion into Ethernet packets requires protocol conversion. The technology is complex.
EPON adopts the Ethernet protocol, and its advantages include mature protocol, simple technology, easy expansion, user-oriented, etc. It is very suitable for the current IP business volume, and is simple and efficient to implement.
3. Different basic communication principles are used
Gpon’s ATM and Epon’s Ethernet solutions. In the development of communication network technology, ATM network cards and Ethernet have had technical disputes for a period of time. History has proved that ATM technology has basically been eliminated and Ethernet has an absolute advantage.
4. Different prices
The implementation complexity of GPON is high, and the price is higher than EPON. The cost of GPON equipment is more than 20% higher than that of EPON equipment. Until now, GPON chipsets are still much more expensive than EPON.
5. Different bandwidth
The EPON system adopts symmetric uplink and downlink transmission, with a link bandwidth of 1.25G, and an effective data bandwidth of 1G for uplink and downlink. EPON can provide users with a bandwidth of less than 1000M.
The GPON system uses asymmetric uplink and downlink transmission, 2.5Gbps or 1.25Gbps downlink, and 1.25Gbps or 622Mbps uplink. GPON has a larger bandwidth than EPON.
In general, GPON is superior to EPON in terms of performance indicators, but EPON has advantages in time and cost. Looking forward to the future broadband access market, it may not be who replaces others, but should be coexistence and complementarity. For customers with high requirements on bandwidth, multi-service and security, and ATM technology as the backbone network, GPON will be more suitable. For the customer base with cost sensitive and low security requirements, EPON has become the dominant one.