EPON SFP VS. GPON SFP: Cost-effective Solution for Access Network

With the increasing demands for higher capacity, more diversity and more personalization of services, the capacity and versatility of access networks needs to be expanded. Passive optical network (PON), as a major technology of FTTH, offers point-to-multipoint (P2MP) network access with lower installation and maintenance costs. EPON (Ethernet PON) and GPON (Gigabit PON) are popular versions of PONs at present. The related technologies keep developing and meanwhile the market of PON components keep growing. PON transceiver (EPON SFP or GPON SFP) is an essential part of PON system, in which a single fiber from a central office optical network unit (ONU) is connected to optical network terminals (ONTs) or optical network units (ONUs) at costomer premises. EPON SFP vs. GPON SFP is today’s main subject matter of this paper.


Passive Optical Network (PON)

Passive optical network (PON) is a form of fiber-optic access network. As the leading technology being used in FTTx (FTTH) deployments, so it is also called FTTH (fiber to the home) network. The typical PON arrangement is a point to multi-point (P2MP) network where a central optical line terminal (OLT) at the service provider’s facility distributes TV or Internet service to as many as 16 to 128 customers per fiber line. A PON reduces the amount of fiber and central office equipment required compared with point-to-point architectures. PON only uses fiber and passive components, thus it costs significantly less than those using active components. However, a PON has a shorter range of coverage limited by signal strength, which is typically limited to fiber cable runs of up to 20 km (12 miles). There are two different solutions developed by the IEEE and ITU-T – EPON and GPON. The main differences between them lie in the protocols used for upstream and downstream communications. The following table shows the detailed information about EPON vs. GPON.


Table 1: EPON vs. GPON

What Is PON Transceiver?

PON transceiver is a bi-directional optical transceiver that uses different wavelengths to transmit and receive signals between the OLT at the CO and the ONUs at the end users’ premises over a single fiber. According to the pluged-in device, PON transceiver can be divided into OLT transceiver module and ONU transceiver module with SFF, SFP/SFP+ or XFP package. Here mainly introduce two common OLT transceivers used in GPON or EPON network: GPON SFP and EPON SFP.



GPON SFP OLT transceiver is designed for OLT side in GPON network. GPON SFP uses 1490nm continuous-mode transmitter and 1310nm burst-mode receiver. The transmitter section uses a 1490nm DFB (Distributed Feed Back) LD with automatic power control (APC) function and temperature compensation circuitry to ensure stable extinction ratio overall operating temperature range. And it is Class I laser compliant IEC825 and CDRH standards. The receiver has a hermetically packaged burst-mode APD-TIA (trans-impedance amplifier) pre-amplifier and a burst-mode limiting amplifier with LVPECL compatible differential outputs. The GPON OLT SFP transceiver is a high performance and cost-effective module for serial optical data communication applications to 2.5Gpbs. For GPON transceivers, there are 2 Class available – Class B+ and Class C+. The table below shows the key differences between GPON SFP class B+ and class C+:

GPON SFP class B+ vs. class C+

Table 2: GPON SFP class B+ vs. GPON SFP class C+


EPON SFP transceiver is the family of high performance optical modules providing a symmetric 1.25 Gb/s downstream and 1.25 Gb/s upstream data link over a single fiber using a 1490 nm continuous-mode transmitter and 1310 nm burst-mode receiver. The transmitter section uses a 1490nm DFB laser for superior performance and is Class 1 laser compliant. The receiver section uses a 1310nm APD, pre-amplifier, and limiting post-amplifier. The receiver does not require a reset pulse between incoming optical packets of varying signal strength. EPON SFP OLT transceivers support 1000BASE-PX20-D for 20 km applications.


In terms of OLT module, there are many similarities through EPON SFP vs. GPON SFP, such as type of laser, transmission distance and communication model. The key difference among them is the sending power and receiver sensitivity. The sending power of GPON SFP Class B+ is 1.5~5dBm, and its receiver sensitivity is -28dBm while the sending power of Class C+ is 3~7dBm and receiver sensitivity is -32dBm. The sending power of EPON SFP is 2~7dBm and its receiver sensitivity is -28dBm. For GPON SFP, the upstream bandwidth is scalable from 155Mbps to 2.5Gbps while the downstream is designed to deliver 1.25Gbps or 2.5Gbps. It is the most widely used consumer broadband service in FTTH networks of present times. On the other hand, EPON SFP supports symmetric bandwidth of 1.25Gbps in both the upstream and downstream directions.


Table 3: EPON SFP vs. GPON SFP


Through EPON SFP VS. GPON SFP, we can see that they are the same in architecture but for different data rate and applications. In terms of cost, The GPON SFP optical module is more expensive than EPON SFP. Because 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. When GPON reaches deployment stage, the estimated cost of a GPON OLT is 1.5 to 2 times higher than an EPON OLT. For the users who have demands of multi-service, high QoS and security, as well as ATM backbone network, GPON SFP seems to be an ideal. And for the one who is much care about the cost and has less security requirements, EPON SFP may be better.

Related Article: Passive Optical Network Tutorial

How to Expand Bandwidth in PON Network with CWDM Technology?

PON (passive optical network) is one of a common optical fiber network architectures. It is characterized by the “splitting” of the optical fiber one or more times, resulting in the sharing of optical fiber among multiple users. However, as networks grow in terms of subscriber counts, the scope and number of services offered, expanding the network bandwidth is inevitable. Coarse Wave Division Multiplexing (CWDM), known for its low cost and scalability to increase fiber capacity as needed, is a preferred method for PON network expansion. This article will focus on using CWDM technology to overcome bandwidth limitations in PON access networks.

CWDM Mux/Demux and OADM (Optical Add-Drop Multiplexer) in Access PON

Fibers in a PON are typically shared with several users. Hence the bandwidth of the fiber originating at the CO (center office) is shared among a group of users. The splitting of the network is accomplished by optical splitters. These splitters can split the fiber 2-32 times, which may introduce high losses in the network. Besides, as different places in a same network need different wavelengths, CWDM Mux is often deployed to multiplex these signals on a single fiber.

In PON (Passive Optical Network) network, whether in ring structures or point-to-point arrangements, different optical nodes need specific wavelengths. Therefore, at each node, a CWDM OADM is used to drop or add certain channels from the fiber as required,. Then the signals will be transmitted to the user through optical fibers. The following picture shows a simple PON network.


How to Expand Bandwidth of PON Network Using CWDM Technology?
Upgrading Access PONs Using Passive CWDM Mux/Demux

In PON networks, OLT has two float directions: upstream (getting an distributing different type of data and voice traffic from users) and downstream (getting data, voice and video traffic from metro network or from a long-haul network and send it to all ONT modules on the ODN).

The following figure represents a situation where existing subscribers intend to upgrade to higher value added bandwidth services. In order to satisfy customers’ needs for IPTV, VoIP, video on demand etc., the 622 Mb/s downstream capacity between the CO and the OLT, providing roughly 20 Mb/s to each subscriber, must increase.

PON network

Considering there may be new subscribers and services added, the targeted bandwidth requires at least a downstream CO/OLT link bandwidth of 2.5Gb/s. Therefore, four CWDM wavelengths are introduced to multiply the channels passing between the CO and OLT. This introduction of passive CWDM Mux/Demux can relieve the fiber exhaust effectively. The below figure shows the upgrading process.

PON upgrade

Advantages of This Upgrade

Compared with laying a new fiber cable, the upgrade with passive CWDM is easily accomplished within hours after some modest investment in network planning. And the sum of material, labor, equipment and training expense is far less, which explain why many enterprises, private business users of LAN and data storage networks use passive CWDM too.

Expanding EPON Bandwidth Using CWDM Mux/Demux

EPON stands for Ethernet passive optical network. It is an enabling technology that benefits consumers. Here is an EPON network, which was conceived to serve up to 64 subscribers. All users share a single bidirectional optical feed line. With the need for IPTV, HDTV and other higher bandwidth services growing, the downstream capacity 16Mb/s should be improved.


The picture below shows the same EPON deployment upgraded to 4Gb/s bandwidth capacity.

EPON network

This upgrade uses 4 channels passive CWDM Mux/Demux to extend the whole network capacity, allowing the downstream capacity increase four times without affecting the upstream traffic.

Advantage of This Expansion

Using CWDM Mux/Demux effectively increases the network bandwidth capacity and reduces the cost. At the same time, it requires minimal modification of the existing infrastructure, which also saves labors.


CWDM technology offers significant benefits of low investment, minimal operating cost and very simple and straightforward upgrade planning and implementation. In addition, passive CWDM also provides scalability and network flexibility for network growth and bandwidth demands in the future. FS.COM supplies different channels of CWDM components. Welcome to contact us via sales@fs.com.

Related article:Examples of CWDM Network Deployment Solution