GPON vs XGS-PON vs EPON: How to Choose and Design a Fibre Access Network

Passive optical networks (PON) have become the standard way to deliver fibre to homes, and they are now moving into hotels, campuses, residential towers and offices. This guide explains how PON works, how GPON, XGS-PON and EPON compare, and how to design a network that performs well today and upgrades easily tomorrow.

How a passive optical network works

A PON has three parts:

• OLT (optical line terminal): the active equipment in the central office or main equipment room. Each OLT port drives one fibre tree.
• ODN (optical distribution network): single-mode fibre and passive optical splitters that divide one fibre into 8, 16, 32, 64 or more branches. No power is needed between the OLT and the user.
• ONU / ONT (optical network unit or terminal): the device at the user side, which provides Ethernet, Wi-Fi, voice or PoE ports.

Downstream traffic is broadcast to all ONUs on a tree and encrypted per user. Upstream, the OLT schedules each ONU's transmission time using dynamic bandwidth allocation (DBA), so users share capacity fairly.

GPON vs XGS-PON vs EPON

GPON is the mainstream choice for FTTH and buildings today. XGS-PON provides 10 Gbps in both directions for multi-gigabit home plans, business services and backhaul for Wi-Fi 7 and 5G small cells. EPON remains a cost-effective option in markets where it is already established.

Many modern OLTs offer combo ports that run GPON and XGS-PON on the same fibre, so operators can upgrade subscribers one at a time without touching the outside plant.

Step 1: Estimate bandwidth per user

Divide the port capacity by the number of users on the tree, then apply a realistic concurrency factor. Example: a GPON port (2.488 Gbps downstream) shared by 64 users gives about 39 Mbps each if everyone downloads at the same moment, but because users are rarely all active, 300–500 Mbps plans are common in practice with good QoS and DBA. For guaranteed business services or very high plans, use smaller splits or XGS-PON.

Step 2: Choose the split ratio and architecture

• Centralised split: one 1:32 or 1:64 splitter per area. Simple to manage and good for dense areas.
• Cascaded split: for example 1:4 at the street and 1:16 in the building. This is flexible for spread-out areas and reduces fibre count.

Leave spare splitter ports for growth, and keep critical sites (hospitals, data rooms) on protected paths using Type B or Type C protection.

Step 3: Calculate the optical power budget

The link must stay within the optics' budget, for example Class B+ (≈28 dB) or C+ (≈32 dB) for GPON. Add up the losses:

• Fibre: about 0.35 dB/km at 1310 nm
• Splitters: about 3.5 dB (1:2), 10.5 dB (1:8), 14 dB (1:16), 17.5 dB (1:32), 21 dB (1:64)
• Connectors and splices: about 0.3–0.5 dB each
• Safety margin: 3 dB for ageing and repairs

Example: 10 km fibre (3.5 dB) + 1:64 split (21 dB) + 6 connectors and splices (2.5 dB) + 3 dB margin = 30 dB. That fits Class C+ optics, but not Class B+.

Step 4: Pick the right ONU for each location

• SFU: single-family bridge ONU with 1–4 Ethernet ports, used with the customer's own router.
• HGU: home gateway with Wi-Fi 6, voice and routing, for FTTH.
• PoE ONU: powers IP cameras and access points directly.
• MDU: 8 to 24 ports for a floor, shop or small building.

Passive optical LAN for enterprises

Inside hotels, campuses and offices, passive optical LAN (POL) uses the same technology to replace floor switches and copper cabling. One OLT in the main equipment room feeds splitters and ONUs on each floor. The result is less power, less space, longer reach and fibre that is ready for future speeds. Combine POL with Wi-Fi 7 access points and PoE where devices need power.

Operations and security

• Use ONU authentication (serial number or password) and PON encryption.
• Enable rogue-ONU detection so one faulty ONU cannot disrupt a whole tree.
• Keep service profiles (VLANs, bandwidth, QoS) as templates for fast provisioning.
• Monitor optical levels to catch dirty connectors and bent fibres early.

Next steps

See the Navijin GPON & fibre access solution and contact our engineers for an optical design and bill of materials.