What are the line rates of GPON, EPON and XGS-PON?
GPON (ITU-T G.984) runs 2.5 Gbps downstream and 1.25 Gbps upstream. EPON (IEEE 802.3ah) runs 1.25 Gbps in both directions. XG-PON (G.987) runs 10 Gbps downstream and 2.5 Gbps upstream. XGS-PON (G.9807) runs 10 Gbps symmetric. 10G EPON offers 10/1 Gbps or 10/10 Gbps depending on the variant.
The downstream rate is shared by every ONU on the PON port. A 1:64 GPON port with 2.5 Gbps gives an average of about 39 Mbps per subscriber at full contention, which is why ISPs plan contention ratios rather than selling the headline rate to every user.
| Technology | Downstream | Upstream | Standard | Typical split |
|---|---|---|---|---|
| EPON | 1.25 Gbps | 1.25 Gbps | IEEE 802.3ah | 1:32 / 1:64 |
| GPON | 2.5 Gbps | 1.25 Gbps | ITU-T G.984 | 1:32 / 1:64 |
| XG-PON | 10 Gbps | 2.5 Gbps | ITU-T G.987 | 1:64 / 1:128 |
| XGS-PON | 10 Gbps | 10 Gbps | ITU-T G.9807 | 1:64 / 1:128 |
| 10G EPON | 10 Gbps | 1 or 10 Gbps | IEEE 802.3av | 1:32 / 1:64 |
How does the split ratio change the choice?
Every extra split costs optical budget. At 1:32 the splitter takes about 16.5 dB; at 1:64 it takes 20.5 dB. Higher-rate PONs often use 1:128 in dense areas, but that takes about 23.5 dB, leaving little margin for a long span. The split ratio is a budget decision, not a headline specification.
For a short in-building ODN, 1:64 is normal. For a 20 km rural span, 1:32 is safer. For XGS-PON with 10 Gbps per port, a 1:128 split still gives about 78 Mbps per subscriber at full contention, but the optical budget becomes the constraint.
Is EPON cheaper than GPON?
Often yes, because EPON ONUs and optics can be lower cost and the protocol is simpler. GPON has a larger ecosystem and is the usual choice where an ISP handover or an existing GPON headend dictates the standard. The difference is smaller than the cost of a wrong split ratio or a rework.
For a private CCTV or campus network, EPON’s symmetric 1.25 Gbps is often enough and the lower cost is attractive. For a residential FTTH network with a carrier handover, GPON is usually the safer choice. For 10G business services, XGS-PON.
Can GPON and XGS-PON share the same fibre?
Yes, with WDM coexistence. XGS-PON uses 1577 nm downstream and 1270 nm upstream; GPON uses 1490/1310 nm. A coexistence element (WDM) at the headend combines them, and an XGS-PON ONU filters the wavelengths it needs. The ODN splitters must work across the full band.
Coexistence lets an operator add 10G services without replacing the GPON ODN. It requires careful optical budget planning because the coexistence element adds loss, and the splitter must be rated for all wavelengths in use.
Which generation should a new project use?
For a new residential FTTH network, GPON is the default; XGS-PON if the business case includes multi-gigabit packages or a 10-year upgrade path. For a private CCTV or campus network, EPON or GPON is usually enough; the ONU cost and the existing headend matter more than the headline rate. For a hotel or MDU with IPTV, GPON with a CATV overlay is common.
Do not choose a generation only by the marketing number. Check the ONU availability, the management system, the optical budget at the planned split, and the cost of the whole chain: OLT port, splitter, ONU, installation and spares.
| Project | Recommended | Reason |
|---|---|---|
| Residential FTTH | GPON, XGS-PON for premium | Ecosystem and carrier handover |
| CCTV / campus | EPON or GPON | Symmetric 1.25G or 2.5G is ample |
| Hotel / MDU + CATV | GPON + 1550 nm overlay | CATV on the same ODN |
| Business 10G services | XGS-PON | Symmetric 10G |
| Upgrade of a GPON ODN | XGS-PON with coexistence | Reuse the fibre and splitters |
Use this on a real site
Send the endpoint count, the longest run, the mains condition and the load. We will apply this calculation to your project and return the optical/power budget with the bill of materials.
