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Ethernet کی نسلیں، لین ریٹس اور الیکٹریکل انٹرفیسز
ہماری ٹیم ترجمے پر کام کر رہی ہے۔ یہ مضمون عارضی طور پر اردو میں دستیاب نہیں ہے، اس لیے اسے انگریزی میں دکھایا جا رہا ہے۔
Every Ethernet speed since 10G has been built from a small set of lane rates — 10G, 25G, 50G, 100G and now 200G per lane — combined in parallel. Knowing which lanes a given speed is made of explains the module's electrical interface, why breakout works or does not, why a 100G module can be either 4 × 25G or 1 × 100G, and what a host and a module have to agree on before the light means anything.
Timeline of IEEE 802.3 projects
| Year | Amendment | Speeds | Lane signalling | Notes |
|---|---|---|---|---|
| 1998 | 802.3z | 1000BASE-SX/LX/CX | 1.25 GBd 8B/10B | GBIC → SFP era |
| 1999 | 802.3ab | 1000BASE-T | 4 pairs, PAM5 | copper 1G |
| 2002 | 802.3ae | 10GBASE-SR/LR/ER/LX4 | 10.3125 GBd 64B/66B | XENPAK/X2/XFP → SFP+ |
| 2006 | 802.3an / aq | 10GBASE-T / LRM | — | copper 10G; MMF 220 m with EDC |
| 2010 | 802.3ba | 40GBASE-SR4/LR4/CR4, 100GBASE-SR10/LR4/ER4 | 4 × 10G / 10 × 10G / 4 × 25G | QSFP+, CFP |
| 2014 | 802.3bj | 100GBASE-CR4/KR4 | 4 × 25G NRZ | introduces RS-FEC (528,514) |
| 2015 | 802.3bm | 100GBASE-SR4, CAUI-4, 40GBASE-ER4 | 4 × 25G | QSFP28 becomes possible |
| 2016 | 802.3by | 25GBASE-SR/LR/CR | 1 × 25G | SFP28; CA-25G-L/S/N cable classes |
| 2017 | 802.3bs | 200GBASE-FR4/LR4/DR4, 400GBASE-SR16/DR4/FR8/LR8 | 50G PAM4 (8 × 50G electrical) | RS-FEC (544,514) KP4 |
| 2018 | 802.3cd | 50GBASE-SR/FR/LR/CR, 100GBASE-SR2/DR/CR2, 200GBASE-SR4/CR4 | 50G PAM4 lanes | SFP56, QSFP56 |
| 2019–21 | 802.3cn / cu | 50/200/400G 40 km ER; 100GBASE-FR1/LR1, 400GBASE-FR4/LR4-6 | 100G PAM4 optical lanes | adopted the 100G Lambda MSA |
| 2022 | 802.3ck / db | 100G/lane electrical (100GAUI-1, 400GAUI-4, 800GAUI-8); 100G/lane VCSEL (SR1, SR4, VR) | 106.25 GBd PAM4 | QSFP112, OSFP 800G |
| 2024 | 802.3df | 800GBASE-DR8/SR8/VR8, -DR4 (200G/lane optical) | 8 × 100G electrical | 800G in OSFP / QSFP-DD800 |
| ~2026 | 802.3dj | 200G/lane electrical and optical; 800GBASE-DR2, 1.6TBASE-DR8 | 212.5 GBd PAM4 | 1.6T OSFP-XD, OSFP |
MSA interfaces (CWDM4, PSM4, ZR…) filled the gaps between these: Optical interface MSAs.
How speeds are built from lanes
| Speed | Electrical lanes (host ↔ module) | Optical lanes (typical) | Module |
|---|---|---|---|
| 10G | 1 × 10G (XFI/SFI) | 1 × 10G | SFP+ |
| 25G | 1 × 25G (25GAUI) | 1 × 25G | SFP28 |
| 40G | 4 × 10G (XLAUI/XLPPI) | 4 × 10G (SR4, LR4) | QSFP+ |
| 50G | 1 × 50G PAM4 or 2 × 25G | 1 × 50G PAM4 | SFP56 |
| 100G | 4 × 25G (CAUI-4) | 4 × 25G (SR4, LR4, CWDM4, PSM4) | QSFP28 |
| 100G | 2 × 50G (100GAUI-2) or 1 × 100G (100GAUI-1) | 1 × 100G PAM4 (DR, FR1, LR1) | QSFP28/QSFP56/QSFP112, SFP112 |
| 200G | 4 × 50G (200GAUI-4) or 8 × 25G | 4 × 50G (FR4, SR4, DR4) | QSFP56 |
| 400G | 8 × 50G (400GAUI-8) or 4 × 100G (400GAUI-4) | 4 × 100G (DR4, FR4, LR4) or 8 × 50G (SR8, FR8) | QSFP-DD, OSFP |
| 800G | 8 × 100G (800GAUI-8) | 8 × 100G (DR8, 2×FR4) or 4 × 200G (DR4) | OSFP, QSFP-DD800 |
| 1.6T | 8 × 200G | 8 × 200G (DR8) | OSFP-XD, OSFP |
When electrical and optical lane counts differ, a gearbox in the module's DSP converts between them — 400GAUI-8 to DR4 is the classic case (Modulation & DSP). When they match (4 × 25G CAUI-4 to SR4), the module is a simple retimer or even unretimed.
Electrical interface names
| Name | Lanes × rate | Used with |
|---|---|---|
| XAUI | 4 × 3.125 GBd (8B/10B) | XENPAK, X2, early 10G |
| XFI / SFI | 1 × 10.3125 GBd | XFP / SFP+ |
| 25GAUI | 1 × 25.78 GBd | SFP28 |
| XLAUI / XLPPI | 4 × 10.3125 | QSFP+ (retimed / parallel physical interface) |
| CAUI-10 / CAUI-4 | 10 × 10.3125 / 4 × 25.78 | CFP / QSFP28, CFP4 |
| 50GAUI-2 / 50GAUI-1 | 2 × 25.78 / 1 × 26.5625 GBd PAM4 | SFP56 |
| 100GAUI-4 / -2 / -1 | 4 × 25.78 / 2 × 26.56 PAM4 / 1 × 53.125 PAM4 | QSFP28 → QSFP112 |
| 200GAUI-8 / -4 / -2 | 8 × 25.78 / 4 × 26.56 PAM4 / 2 × 53.125 PAM4 | QSFP56 → QSFP112 |
| 400GAUI-16 / -8 / -4 | 16 × 25.78 / 8 × 26.56 PAM4 / 4 × 53.125 PAM4 | CFP8 → QSFP-DD/OSFP |
| 800GAUI-8 | 8 × 53.125 GBd PAM4 | OSFP, QSFP-DD800 |
The GBd figures include FEC and 64B/66B overhead: 25.78 GBd carries 25 Gb/s of payload, 53.125 GBd PAM4 carries 100 Gb/s. These names appear in CMIS application descriptors as the host-interface half (SFF-8024).
What must match
- Lane rate and count on the electrical side — a 4 × 25G port cannot drive a 2 × 50G module even if both say "100G".
- Modulation — NRZ lanes and PAM4 lanes are different physical layers.
- FEC — RS(528) for 25G NRZ lanes, RS(544) for all PAM4; mandatory or optional per PMD (FEC & link training).
- Encoding — 8B/10B (1G) vs 64B/66B (10G+); a dual-rate module switches both.
- Optical PMD at both ends — the wavelength, fibre and reach in Optical interfaces and the PMD reference.
The module declares all of this in its identity — nominal rate, encoding, compliance or application codes — and the host refuses combinations it cannot drive (Speed & rate).
In CodingBox
The Check transceiver screen shows the nominal lane rate, encoding and, for CMIS modules, the host-interface IDs of each application, so you can see at a glance whether a module is 4 × 25G or 2 × 50G before it meets a port.
The 1.6T form factors that carry 802.3dj lanes: OSFP224 (8 × 200G) and OSFP-XD (16 × 100G).
The host-side names of these lane bundles — CAUI-4, 400GAUI-8, 800GAUI-8 — with C2M compliance points, OIF CEI mapping and electrical-to-optical lane conversion: XGMII, XAUI and the AUI family.