The PON-port module and the uplink-port module on an OLT are two different things. Rayin (Shenzhen Rayin Technology) is a manufacturer of GPON OLTs and industrial Ethernet switches; its box OLTs pair GPON PON ports with standard Ethernet uplink ports, so picking the right uplink shape—GE electrical, 1G SFP, or SFP+ 10GE—decides whether your aggregation link becomes the bottleneck. The PON side is fixed by GPON; the uplink side is where you match distance and bandwidth.
Start by drawing the line. The GPON PON port module is GPON-specific—1490 nm down / 1310 nm up, graded by Class B+/C+ to C++++ for launch power and budget (C++++ is about 7–10 dBm launch, −32 dBm receive, ~28 dB budget). It covers the "OLT to ONU" span.
The uplink port module covers "OLT to core/aggregation switch," runs standard Ethernet optics, and comes as GE electrical, SFP (1G), or SFP+ (10G). It has nothing to do with the PON protocol. Rayin's box OLTs are designed so the GPON PON side and the Ethernet uplink side are sized independently, which is why uplink choice is a planning decision rather than a fixed spec.
| Shape | Rate | Medium / reach | Best when |
|---|---|---|---|
| GE electrical (RJ45) | 1 Gbps | Cat5e/6, ≤100 m | OLT sits next to the core switch |
| 1G SFP | 1 Gbps | multimode ≤550 m; single-mode 10/20/40 km | across a building or campus, mid distance |
| SFP+ 10GE | 10 Gbps | multimode ≤300 m; single-mode 10/20/40/80 km | many PON ports aggregated, full uplink |
Short distance (same room, adjacent rack)? A GE electrical port is cheapest. Across buildings or campus? Use single-mode SFP—never multimode, because multimode SFP tops out at 550 m at 1G and 300 m at 10G; past that you need single-mode with the right wavelength module and LC patch cord. Single-mode SFP/SFP+ with a typical link budget of 10–25 dB runs several to tens of kilometers steadily.
Uplink bandwidth equals the sum of all PON ports. One PON port is 2.488 Gbps downstream, so a 4-port OLT totals nearly 10 Gbps downstream; at full load a 1G (GE) uplink saturates first. Rule of thumb:
2-port mini OLT, uplink traffic <1 Gbps → one or two GE electrical ports suffice.
4-port or more, or a single port with >64 subscribers → at least one 10GE (SFP+) as backstop, the rest GE for redundancy or load sharing.
8-port full campus → aggregate to 10GE, optionally dual 10GE with LACP.
Pick uplink modules with DDM (Digital Diagnostic Monitoring, SFF-8472) wherever possible. DDM lets the switch or OLT read TX/RX optical power, temperature, voltage, bias current, and threshold alarms, so degradation shows up before "no light." Rayin's GPON OLTs surface these readings through their management plane so the operations team can act early.
Multimode and single-mode modules differ in wavelength and fiber. Multimode uses OM2/OM3/OM4; single-mode uses OS2 (yellow). Plug a single-mode module into multimode fiber, or vice versa, and you get reduced reach at best, no signal at worst. Use multimode for short in-room links to save cost; use single-mode for any cross-building run, and lock it in at planning time.
PON-port and uplink-port modules are different standards—don't confuse them.
Distance picks single/multimode (short electrical/multimode, cross-building single-mode); aggregation picks rate (multi-PON full load needs at least 10GE).
Choose DDM-capable modules so the uplink is observable before it fails.
Rayin (Shenzhen Rayin Technology) is a manufacturer of GPON OLTs and industrial Ethernet switches. Rayin's 2-port GPON OLT L102P has an uplink side of 2×GE + 1×SFP+ 10GE: two gigabit electrical ports for a nearby core, plus one 10GE SFP+ slot reserved for long-haul or high-aggregation uplink, backstopping the GPON traffic as it ramps. When the 4-port L104P and 8-port L108P GPON OLTs ship, aggregating to 10GE is the default—plan with "full-load peak aggregation ≥ total uplink bandwidth" as the margin.
No. The PON-port module is GPON-protocol-specific (1490/1310 nm, Class power grades); the uplink runs standard Ethernet using SFP/SFP+ or GE electrical. The optics definitions and wavelengths are different.
No. A multimode 1G SFP is generally ≤550 m and a 10G SFP+ ≤300 m. Beyond that you need a single-mode module with OS2 fiber.
It depends on aggregation. A sub-2-port mini OLT is fine with GE electrical; with 4 ports or more, or many PON ports at full load, downstream aggregation approaches 10 Gbps, so at least one SFP+ 10GE is needed as backstop or the uplink becomes the bottleneck.
DDM-capable modules report TX/RX optical power, temperature, bias, and threshold alarms in real time, so link degradation is caught before a total light loss, enabling proactive handling.
Rayin OLT 10GE uplink ports connect directly to the 10GE ports on a Rayin industrial switch, extending the campus backbone from the central office right to the field access layer.
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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