EPON (GEPON) ONU : functions, types and how to choose
Contents
The EPON ONU (Optical Network Unit, Ethernet Passive Optical Network) — also called GEPON for its Gigabit variant — is the terminal equipment placed at the subscriber's premises on an FTTH network operated under the EPON standard. It converts the incoming optical signal from the passive fiber network into an electrical Ethernet signal usable by household equipment.
This guide explains the different types of EPON ONU (WiFi, PoE, CATV, reverse PoE), their technical specifications and how to choose the model suited to your deployment.
What is an EPON ONU ?
In an EPON (Ethernet PON) network, the architecture is point-to-multipoint :
- OLT (Optical Line Terminal) on the operator side
- Passive fiber network with optical splitters (1×32, 1×64)
- ONU (Optical Network Unit) on the subscriber side — the terminal equipment
The ONU performs three key functions :
- Optical/electrical conversion — decodes the light signal (1490 nm download / 1310 nm upload)
- TDMA demultiplexing — extracts the frames intended for this client from the shared stream
- User interface — provides Ethernet, WiFi, POTS (telephony) or CATV ports depending on the model
EPON is the dominant standard in Asia and on some European operator networks. In France, operators mostly use GPON/XGS-PON (ITU-T) but some enterprise networks and private campuses run on EPON (IEEE 802.3ah) for its lower hardware cost.
Types of EPON ONU available
| ONU type | Output ports | Distinctive feature | Typical use |
|---|---|---|---|
| Simple ONU | 1× Ethernet | Basic conversion | Connection to external switch/router |
| WiFi ONU | 1-4× LAN + WiFi | Integrated router | Residential all-in-one |
| PoE ONU | 1-4× Ethernet PoE | Powers cameras/APs | Video surveillance, WiFi hot-spots |
| Reverse PoE ONU | Ethernet + power | Powered by PSE | Areas without mains socket |
| CATV ONU | Ethernet + RF CATV | Decodes analog TV | Hospitality, shared TV |
| Triple-play ONU | LAN + WiFi + POTS | Internet + TV + telephone | Residential operator box |
WiFi ONU: detailed specifications (V2802EW 1GE+1FE)
The V2802EW ONU (typical WiFi EPON model) combines a Gigabit port, a Fast Ethernet port and an integrated WiFi access point :
| Parameter | Value |
|---|---|
| WiFi standard | IEEE 802.11b/g/n |
| Frequency | 2,400-2,4835 GHz (2.4 GHz band) |
| MIMO | 2T2R, throughput up to 300 Mbps |
| Antennas | 2× external 5 dBi |
| Number of channels | 13 (Europe) |
| Modulation | DSSS, CCK, OFDM |
| Coding | BPSK, QPSK, 16QAM, 64QAM |
| Multi-SSID | Supported (up to 4 networks) |
| Security | WPA/WPA2 PSK, MAC filtering |
For modern deployments, favor ONU with WiFi 5 (802.11ac) or WiFi 6 (802.11ax) — 802.11n is now dated. Elfcam also offers ONU with dual radio 2.4/5 GHz for premium residential deployments.
Standard PoE and reverse PoE ONU (V2810E-4PD)
Standard PoE ONU
The Ethernet ports of the ONU deliver PoE power (802.3af/at) to connected equipment : IP cameras, WiFi access points, VoIP phones. Avoids multiplying mains sockets on the client side.
Reverse PoE ONU
The ONU itself is powered via its Ethernet port by a remote PSE (Power Sourcing Equipment). This is the opposite of standard PoE. Use cases :
- Areas without a mains socket near the installation point (above ground, attics, technical cabinets)
- Outdoor deployments — power comes from a protected central rack
- Parks, campsites, rural areas — the ONU can be placed 100 m from the electrical room
Reverse PoE: a key use case
For installations in a campsite, hotel, exhibition park, placing the ONU in outdoor cabinets without having to run 230V is a huge gain. The centralized PSE in the technical rack powers up to 24 ONU via Ethernet, simplifying installation and maintenance.
CATV ONU for analog TV distribution
CATV ONU (Cable Television) include a 75 Ω coaxial RF output port to carry an analog or digital (DVB-C) TV signal. Typical use :
- Hotels and tourist residences (shared channels)
- Senior residences with analog package
- Older buildings with existing coaxial infrastructure
The TV signal arrives on an additional wavelength (generally 1550 nm) injected into the same fiber as the data. The CATV ONU separates the two streams and provides one over Ethernet, the other over coaxial RF.
How to choose your ONU ?
- PON standard — EPON (IEEE 802.3ah) or GPON (ITU-T G.984) ? Depends on your OLT.
- Required throughput — 100 Mbps (basic EPON), 1 Gbps (GEPON), 10 Gbps (10G-EPON)
- Type of services — Ethernet only, integrated WiFi, PoE, CATV, telephony?
- Number of LAN ports — 1, 2, 4, 8
- Local power or reverse PoE ?
- Form factor — standalone enclosure, 19" rack, outdoor IP65
- Chipset — Broadcom, Cortina, Realtek, ZTE (OLT compatibility)
Complementary Elfcam products
- SC/APC patch cords for ONU to socket connection
- Fiber converters to extend the Ethernet link
- SFP modules if your ONU has a modular slot
- PLC splitters for point-to-multipoint networks
Installation and configuration
- Fiber connection : connect the SC/APC patch cord from the socket to the ONU port (usually green SC/APC or LC/APC)
- Power : 12V mains adapter (supplied) or PoE injector
- OLT activation : the operator OLT must recognize the serial number or MAC of the ONU
- WiFi configuration : via the ONU web interface (default IP often 192.168.1.1)
- Test : ping, throughput test, optical signal check (Rx, Tx)
FAQ — EPON / GEPON ONU
1Difference between EPON and GEPON ?
GEPON : marketing synonym for EPON (Gigabit Ethernet PON), often used in Asia. Same technical characteristics.
10G-EPON : evolution to 10 Gbps down, 1 or 10 Gbps up. For a modern network, favor 10G-EPON or XGS-PON (G.9807, 10 Gbps symmetrical).
2EPON ONU vs GPON ONT : interchangeable ?
3What is the max distance with an EPON ONU ?
4How to register an ONU on the OLT ?
- Auto-learning : the OLT automatically detects the connected ONU and requests validation
- Manual registration by serial number (printed on the ONU)
- Registration by MAC address or LOID (logical ONU identifier)
5Is 802.11n WiFi ONU enough or should I move to WiFi 6 ?
6Reverse PoE : how much power is needed ?
7Can an operator ONU be replaced with an Elfcam ONU ?
8Warranty and support on Elfcam ONU ?
In summary
An EPON/GEPON ONU is the client terminal of an FTTH network under the EPON standard. Choose according to type of services (WiFi, PoE, CATV), PoE power, chipset and OLT compatibility. For modern 2024+ deployments, favor 10G-EPON ONU or migrate to XGS-PON.
Consult our Elfcam project team for complete ONU solutions, or discover our fiber converters and SFP modules to complete your deployment.
