With the rapid development of Fiber to the home (FTTH), Gigabit Passive Optical Networks (GPON) and Ethernet Passive Optical Networks (EPON) are becoming more and more popular in the market. Both GPON and EPON belong to PON, which are separately developed by the ITU-T and IEEE to enable Gigabit rate solutions to deliver Ethernet and IP services. Many people would like to learn more about the difference between GPON and EPON when they are making a decision. Gladly, in the article, we are going to make a comparison from five aspects.
Part I. GPON vs EPON, what’s the difference?
1. Data Rate
GPON supports a variety of data rate levels including asymmetric uplink and downlink rates, downlink 2.5Gbps or 1.25Gbps, uplink 1.25Gbps or 622Mbps. Users can determine uplink and downlink rates according to actual needs, select the corresponding optical transceiver and improve the cost performance of the optical device.
EPON provides a fixed uplink and downlink data rate of 1.25Gbps and adopts 8b / 10b line coding but the actual rate is 1Gbps.
Verdict: GPON is better than EPON.
2. Splitter Ratio
GPON supports 1:32, 1:64, 1:128. There are multiple selectivities but the cost advantage is not obvious. The maximum physical distance that a GPON system can support is 20 km when the optical splitting ratio is 1:16. When it comes to 1: 32, the maximum physical distance should be 10 km.
EPON owns 1:16~1:32. In fact, it can also achieve a higher splitter ratio, such as 1: 64,1: 128 and EPON OLT can support more EPON ONU. But the splitter ratio is mainly restrained by the performance of the optical module in that a large splitter ratio will increase the cost of the optical module. When the PON insertion loss is 15-18 dB, the large splitter ratio will reduce the transmission distance. Thus, many users choose to share bandwidth.
Verdict: Equal
3. QoS(Quality of Service)
GPON has integrated QoS handling involving Ethernet, TDM, and ATM, which is a great advantage for many operators. Besides, GPON has more bandwidth than EPON. Its service bearer is more efficient and the splitting capability is stronger. It can transmit more bandwidth services, achieve more user access, ensuring multiservice and QoS.
EPON does not include any inherent QoS capability. However, PON systems aren’t really viable for operators without a form of QoS, and so many vendors that use EPON choose to use VLAN (Virtual Local Area Network) tags to solve this problem. However, this can be a very costly solution.
Verdict: GPON is superior to EPON.
4. Operate and maintain (OAM)
GPON has powerful OAM capabilities. Three types of OAM channels including embedded OAM channels, PLOAM and OMCI are provided from the perspective of consumer demand and operator operation and maintenance management, which forms a C/M Plane (control/management plane) by bearing different tasks. For example, PLOAM is responsible for data encryption, status detection, error monitoring, etc.
EPON simply uses optional support like the ONT far-end fault indication, loopback, and link monitoring instead of overemphasizing OAM.
Verdict: The OAM of GPON is stronger.
5. Costs
The cost of GPON or EPON depends on the OLT, ONU/ONT and passive optical components. The price of different GPON OLT or EPON OLT is also different. For the same number of users, the cost for the fiber and cabinet with EPON is similar to that with GPON. The cost of OLT and ONT is decided by the ASIC (Application Specific Integrated Circuit) and optical transceiver modules. The GPON chipsets available in the market are mostly based on FPGA (Field Programmable Gate Array), which is more expensive than the EPON MAC (Media Access Control) layer ASIC. Moreover, the optical module of EPON is cheaper than GPON.
Verdict: EPON is more cost-effective than GPON.
Part II. Related Product
V-SOL has developed a series of GPON and EPON products in accordance with the demands. Not only are there are EPON/GPON ONU/OLT, but also xPON ONU router that supports dual modes including EPON and GPON are provided.
Part II. Summary
EPON and GPON have their own advantages and disadvantages. GPON is better than EPON in the performance. It will be more suitable for customers with high requirements of bandwidth, multi-service, QoS and security, and ATM backbone network. In contrast, it would be better to choose EPON for those who pay more attention to the cost and lay less emphasis on service and security. At present, although EPON is more popular, GPON is catching up and occupies an important place in the market. You just need to choose in line with your demands.
