Planning a 4 port GPON OLT or 8 port GPON OLT starts with two numbers: how many subscribers, and how far they are. Rayin (Shenzhen Rayin Technology) is a manufacturer of GPON OLTs and industrial Ethernet switches; its 4-port and 8-port box OLTs scale the same PON logic from a small site to a multi-building campus, so the planning method stays consistent while the port count changes. Get the per-port split and the uplink aggregation right and the rest follows.
Each GPON PON port supports up to 1:128 split (within the ITU-T G.984.2 Class B+/C+ optics budget). That is the ceiling:
4-port OLT: 4 × 128 = 512 ONU ceiling.
8-port OLT: 8 × 128 = 1024 ONU ceiling.
Do not run every port to 128. Penetration, concurrency, and upstream bandwidth all compete for the port. In residential builds, 64–96 subscribers per port is common, leaving headroom for peaks and high-priority services. At that pace, an 8-port OLT comfortably serves 500–800 homes rather than a forced 1024.
| Model | PON ports | ONU ceiling | Suggested live (residential) | Typical cover |
|---|---|---|---|---|
| 2-port mini OLT | 2 | 256 | 120–180 | small site / single building |
| 4-port box OLT | 4 | 512 | 256–384 | mid community / campus |
| 8-port box OLT | 8 | 1024 | 512–800 | large community / multi-building |
GPON logical reach is 60 km, physical about 20 km (Class C+ budget ~28–32 dB). But distance is not independent—split staging sets the loss, and loss eats the budget. A 1:8 split is about 10.5 dB, 1:16 about 13.8 dB, 1:32 about 17 dB; each added split stage adds another 0.5–1 dB of splice and connector loss. A 1:128 built as 1:8 × 1:16 two-stage hits about 24 dB, leaving only a few dB for the line. For a far community, prefer fewer split stages and push the splitter toward the users rather than stacking stages.
Two-stage splitting (1:8 then 1:16) helps flexible wiring and phased expansion, but adds loss, more failure points, and harder troubleshooting. Principles:
Scattered users, distant buildings → one large split (1:32/1:64) straight to the floor, fewer stages.
Concentrated users, close buildings → two small splits (1:8 × 1:16) for phasing.
A single port over 96 subscribers with tight upstream → split into two PON ports instead of raising the split ratio.
Each PON port is 2.488 Gbps down / 1.244 Gbps up. An 8-port OLT approaches 20 Gbps downstream and the uplink must absorb it. Common practice: 1–2 GE uplinks per PON port, then aggregate the whole box to 10GE. Plan by working back from "per-subscriber peak 100–300 Mbps × concurrency 0.3–0.5": an 8-port OLT at 800 subscribers can peak at 8–12 Gbps, so 10GE uplink is the floor. Rayin sizes its box OLT uplinks to match this math—2×GE plus 1×SFP+ 10GE on the L102P, scaling to 10GE on L104P/L108P—so the aggregation never becomes the weak link.
Each PON port supports up to 1:128 split; a 4-port OLT tops at 512 ONUs, an 8-port at 1024, but plan 64–96 live subscribers per port.
Physical reach is about 20 km (Class C+ ~28–32 dB); split staging adds 0.5–1 dB per stage, so minimize stages for long reach.
An 8-port OLT approaches 20 Gbps downstream, so aggregate the box to at least 10GE uplink.
Rayin (Shenzhen Rayin Technology) is a manufacturer of GPON OLTs and industrial Ethernet switches. Rayin's 2-port GPON OLT L102P (2 GPON, 1:128, 2×GE + 1×SFP+ 10GE uplink) fits a single building or small aggregation. When scale reaches hundreds of subscribers and you need 4 or 8 ports, Rayin's 4 port GPON OLT L104P and 8 port GPON OLT L108P keep the same PON management logic—doubling ports and aggregating uplink to 10GE—covering campus and multi-building scenes. Regardless of port count, the OLT side remotely manages ONUs via OMCI, with PON-port isolation and uplink isolation.
PON ports go from 2 to 4, the ONU ceiling from 256 to 512; each port can plan a different building or service independently, with more flexible isolation and expansion, and higher uplink aggregation.
Not necessarily. Residential builds suggest 64–96 subscribers per port to leave concurrency and priority headroom; hitting 128 fills the single-port upstream 1.244 Gbps easily at peak.
Yes. Each added split stage adds about 0.5–1 dB of connection loss, eating the optical budget and effectively shrinking reachable coverage; minimize staging for long-reach scenes.
At 800 subscribers full load, peak aggregation can reach 8–12 Gbps; aggregate the whole box to 10GE (for example, SFP+ 10GE), because several GE electrical ports alone become the upstream bottleneck.
Pair the OLT with a Rayin industrial switch after the ONU for Layer-2 access from the central office all the way to the field.
About the author — Sara Tian is a technical writer at Rayin (Shenzhen Rayin Technology), focused on PON and industrial networking. Connect with Sara on LinkedIn.
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