PON standards
PON comes in two families — the ITU-T G-series (GPON and its successors) and the IEEE EPON series. They differ in rates, framing and wavelength plans.
ITU-T family
| Standard | Spec | Downstream / Upstream |
|---|---|---|
| GPON | G.984 | 2.5G / 1.25G |
| XG-PON | G.987 | 10G / 2.5G |
| XGS-PON | G.9807.1 | 10G / 10G |
| NG-PON2 | G.989 | 4×10G (TWDM), tunable |
IEEE family
- EPON (802.3ah) — 1G symmetric, Ethernet framing.
- 10G-EPON (802.3av) — 10G downstream, 1G or 10G upstream.
Wavelengths and coexistence
Each standard defines its own downstream/upstream wavelengths so that newer PONs can share the same fibre plant as older ones through coexistence elements. NG-PON2 goes further with tunable ONU optics that pick a wavelength pair.
Because the wavelength plan is part of the standard, confirming a module's wavelength matters — CodingBox surfaces it from the module memory.