EPON vs. GPON – A Practical Comparison
EPON, based on Ethernet technology, is compliant with the IEEE 802.3ah (mid-2004) Ethernet in the First Mile standard that is now merged into the IEEE Standard 802.3-2005. It is a solution for the "first mile" optical access network. While GPON, or Gigabit PON, is expected to prevail as a leading optical access technology and to eliminate the bandwidth bottleneck in the last mile. Its requirements were set force by the Full Service Access Network (FASN) group, which was later adopted by ITU-T as the G.984.x standards.
In EPON, both downstream and upstream line rates are 1.25 Gb/s, but due to the 8B/10B line encoding, the bit rate for data transmission is 1 Gb/s. GPON, on the other hand, supports a symmetrical data rate of 1.25 Gbps in both streams, as well as a data rate of 2.5 Gbps in downstream and a data rate of 1.25 Gbps in upstream. Hence GPON is better than EPON in this aspect. The following table has a brief comparison of GPON and EPON technology in the PON upstream and downstream bandwidth, bandwidth efficiency and the transmission.
Besides the above characteristics, perhaps the most striking distinction between the two protocols is a marked difference in architectural approach, especially in layering. The image below will help you to figure it out.
The use of EPON allows carriers to eliminate complex and expensive ATM and Sonet elements and to simplify their networks, thereby lowering costs to subscribers. Currently, EPON equipment costs are approximately 10 percent of the costs of GPON equipment, and EPON equipment is rapidly becoming cost competitive with VDSL.
It is hard to say GPON is better than EPON, or vice verse. They each have their merits and demerits. When it comes to certain IP/Ethernet services, EPON is more suitable and cost effective. While GPON has its own advantages in higher bandwidth, faster transmission rate and supporting triple-play services. Until now, EPON is still the mainstream of PON, especially in the Asian countries, but GPON is expanding quickly lately. Fiberstore supplies a large amount of PON equipment including GPON OLT, GPON ONT, EPON OLT, EPON ONU and PON splitters, etc. We are welcomed for all our customers to meet with fast growing demand of PON deployment.