Understanding the Key Differences Between EPON and GPON

EPON and GPON

Fiber is seeing wide adoption in the access network to expand capacity and versatility. With PON (Passive Optical Network ) technology gaining popularity and FTTH (Fiber to the Home) networks becoming the trend of future access network, two point-to-multipoint (P2MP) standards – Ethernet passive optical networking (EPON) and GPON (Gigabit Passive Optical Network) are both in active deployment. This post will briefly describe the differences between these two technologies.

PON Technology

A PON is a fiber network that only uses fiber and passive components like splitters and combiners rather than active components like amplifiers, repeaters, or shaping circuits. Such networks cost significantly less than those using active components. Passive Optical Network (PON) technology is a high-speed, cost-effective fiber-optic communication system designed for broadband access networks. PONs enable the efficient distribution of data, voice, and video services by using passive optical components. Hence eliminates the need for active electronic devices in the network infrastructure.

In a PON, a single optical fiber is shared among multiple end-users through the use of passive splitters. This reduces the amount of fiber and equipment needed. This technology is characterized by its simplicity, reliability, and scalability.

PON technology has evolved over the years, with various standards such as EPON (Ethernet PON), and GPON (Gigabit PON). This provides different levels of performance and capabilities. PONs play a crucial role in delivering reliable and high-speed broadband access to homes, businesses, and other end-users.

Introduction to EPON and GPON

EPON stands for Ethernet passive optical network. The EPON uses Ethernet packets instead of ATM (Asynchronous Transfer Mode) cells. EPON also uses Internet Protocol (IP) to carry data, voice, and video data. It generally delivers 1G symmetrical bandwidth, which makes it a popular choice. 

GPON stands for Gigabit Ethernet passive optical network. GPON uses ATM for voice, Ethernet for data, and proprietary encapsulation for voice. It offers faster Gbps than EPON on downstream and upstream bandwidths.

Comparison between EPON and GPON

In this sections, we aim to provide a comprehensive comparison between EPON and GPON.

EPON is defined by the IEEE 802.3 standard, ratified as 802.3ah-2004 for a base rate of 1.25 Gbps (1.0 Gbps prior to 8B/10B coding), and the IEEE 802.3av standard introduces the 10Gbps variant known as 10G-EPON. Notably, the upstream and downstream data rates of EPON are symmetrical.

 Data Rate

In contrast, GPON offers versatility in terms of bit rate options within the same protocol. It supports symmetrical data rates of 622 Mbps, 1.25 Gbps, and asymmetrical rates of 2.5 Gbps downstream and 1.25 Gbps upstream. This flexibility allows users to choose the upstream and downstream data rates according to their specific requirements. This makes GPON more adaptable than EPON

Splitter Ratio

GPON supports 1:32, 1:64, 1:128. There are multiple selectivity’s 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. It 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.

QoS(Quality of Service)

The Ethernet protocol lacks inherent Quality of Service (QoS) capabilities. As QoS is essential for a viable PON system, most vendors address this in EPON by utilizing VLAN tags. While this effectively resolves the QoS challenge, it introduces higher costs. The manual provisioning of VLAN tags, as there is no automatic provisioning, further contributes to these elevated costs. In contrast, GPON incorporates integrated QoS handling, making it superior to EPON in terms of QoS. QoS implementation in EPON tends to be more costly compared to the integrated QoS features in GPON. 

QoS Quality of Service

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. Thus the OAM of GPON is stronger

Practical Solution

The EPON Solution provide high-speed transmission up to 1.25G/1.25G over 20KM, meeting growing bandwidth demands. Ensuring reliability, they support industrial temperatures and offer resistance to lightning and interference. Cost-effective with abundant fiber materials, EPON outperforms copper cables in speed and economic benefits within a 20km range.

While the GPON Solution GPON Solution stands out with its versatile business access capabilities, accommodating E1 circuit, Ethernet, and ATM services for comprehensive voice, data, and video applications. Offering efficient coverage with a 1:128 splitting ratio and a 20 km access layer radius, it combines scalability and easy expansion. Moreover, the network’s reliability is underscored by its support for industrial temperatures and airtight TO packaging, making it adaptable to diverse environments, including edge computer rooms. Additionally, the GPON network can seamlessly upgrade to XGS-PON to meet increasing demands for higher bandwidth and faster data rates by replacing equipment.

Conclusion

In conclusion, both EPON and GPON are robust passive optical networking technologies that offer high-speed connectivity and support various services. The choice between EPON and GPON depends on factors such as existing infrastructure, service requirements, bandwidth needs, and scalability considerations. EPON’s simplicity and interoperability with Ethernet networks make it suitable for certain deployments, while GPON’s efficient protocol and flexible QoS management make it a preferred choice for others. Understanding the differences between EPON and GPON is crucial for network operators and service providers to make informed decisions and deploy the most suitable technology to meet their specific needs.



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