| Full title | IEEE 802.3, IEEE Standard for Ethernet. Optical PHYs are specified in individual clauses, added by amendments |
| Publisher | IEEE Standards Association, IEEE 802.3 Ethernet Working Group |
| Current edition | IEEE 802.3-2022, published 29 July 2022. It supersedes IEEE 802.3-2018 |
| Status | Active. Amended since 2022 by, among others, 802.3db-2022 and 802.3df-2024. A further revision project, P802.3, is authorised |
| Related standards | ISO/IEC 11801-1, IEC 60793-2-10 (multimode fibre), ITU-T G.652, IEC 61280-4-1 and -4-2 (fibre testing), ANSI/TIA-568.3 |
What it covers
IEEE 802.3 defines Ethernet. Each optical physical layer (PHY) has its own clause, which sets the optical transmitter and receiver limits, the fibre type and the operating range. New PHYs are added by amendments, which are then folded into the next revision of the base standard.
This page lists the optical PHYs commonly used in buildings, campuses and data centres. Reach figures are taken from IEEE 802.3 tables or from the approved IEEE project objectives.
Reading the names
- The number before BASE is the data rate, for example 10G or 400G.
- S or SR PHYs run on multimode fibre (MMF) at short wavelengths, mostly around 850 nm. 400GBASE-SR4.2 uses two short wavelengths in both directions on each fibre.
- A trailing number gives the parallel structure. 400GBASE-SR8 uses eight pairs of MMF. 400GBASE-SR4.2 uses four pairs.
- LR, DR and FR PHYs run on single-mode fibre (SMF).
Multimode PHYs and reach
1000BASE-SX (Clause 38)
Operating range for 1000BASE-SX (IEEE 802.3 Clause 38):
| Fibre | Modal bandwidth at 850 nm | Range |
|---|---|---|
| 62.5 µm MMF | 160 MHz·km | 2 m to 220 m |
| 62.5 µm MMF | 200 MHz·km | 2 m to 275 m |
| 50 µm MMF | 400 MHz·km | 2 m to 500 m |
| 50 µm MMF | 500 MHz·km | 2 m to 550 m |
| SMF | N/A | Not supported |
10GBASE-SR (10GBASE-S, Clause 52)
| Fibre | Modal bandwidth at 850 nm | Operating distance |
|---|---|---|
| 62.5 µm MMF | 160 MHz·km | 26 m |
| 62.5 µm MMF | 200 MHz·km | 33 m |
| 50 µm MMF | 400 MHz·km | 66 m |
| 50 µm MMF | 500 MHz·km | 82 m |
| 50 µm MMF | 2000 MHz·km | 300 m |
2000 MHz·km is the effective modal bandwidth of OM3 fibre. The table above shows the earlier fibre grades listed in Clause 52. See the current Clause 52 table for OM4.
25G to 400G multimode PHYs
| Amendment | PHYs | Clause | IEEE reach objective |
|---|---|---|---|
| 802.3ba-2010 | 40GBASE-SR4, 100GBASE-SR10 | 86 | At least 100 m on OM3 MMF |
| 802.3bm-2015 | 100GBASE-SR4 | 95 | Up to at least 100 m of MMF |
| 802.3by-2016 | 25GBASE-SR | — | Single lane, consistent with Clause 95 |
| 802.3cd-2018 | 50GBASE-SR, 100GBASE-SR2, 200GBASE-SR4 | 138 | Up to at least 100 m of MMF |
| 802.3bs-2017 | 400GBASE-SR16 | — | At least 100 m of MMF |
| 802.3cm-2020 | 400GBASE-SR8, 400GBASE-SR4.2 | 138 (SR8) and 150 (SR4.2) | At least 100 m on eight pairs (SR8) or four pairs (SR4.2) of MMF |
| 802.3db-2022 | 100GBASE-SR1/VR1, 200GBASE-SR2/VR2, 400GBASE-SR4/VR4 | 167 | Up to at least 50 m and up to at least 100 m on one, two or four pairs of MMF |
The reach objectives are minimum targets set when each project started. The published clauses give the operating range for each fibre grade, which can be shorter on OM3 than the headline objective. Check the clause table for the fibre installed.
Single-mode PHYs
| Amendment | PHYs (examples) | SMF reach objectives |
|---|---|---|
| 802.3ae-2002 | 10GBASE-LR, 10GBASE-ER | At least 2 km, 10 km and 40 km over SMF |
| 802.3ba-2010 | 40GBASE-LR4, 100GBASE-LR4, 100GBASE-ER4 | 40G: at least 10 km. 100G: at least 10 km and 40 km |
| 802.3bs-2017 | 400GBASE-DR4, 400GBASE-FR8, 400GBASE-LR8 | At least 500 m, 2 km and 10 km of SMF |
| 802.3cd-2018 | 100 Gb/s single-lane SMF PHY | Duplex SMF, up to at least 500 m |
The objectives list the reaches each project had to support. Which PHY meets which reach is set in the individual clauses and is not reproduced here.
How it relates to other standards
| Document | Relationship |
|---|---|
| IEC 60793-2-10 and ANSI/TIA-568.3 | Specify the multimode fibre categories and modal bandwidths that correspond to the OM3, OM4 and OM5 grades |
| ITU-T G.652 | Single-mode fibre characteristics |
| ISO/IEC 11801-1 | Defines optical fibre channel classes and lists supported applications |
| IEC 61280-4-1 and IEC 61280-4-2 | Field test methods for installed multimode and single-mode cabling |
| IEC 61754 series | Connector interfaces such as LC and MPO used by duplex and parallel PHYs |
What it means in practice
- Reach depends on the fibre grade. Record the OM grade of installed multimode fibre before choosing optics.
- Older 62.5 µm and 50 µm (400 to 500 MHz·km) fibre limits 10GBASE-SR to 82 m or less.
- Parallel PHYs such as SR4, SR8 and DR4 need multi-fibre links, usually terminated with MPO connectors. Duplex PHYs need one fibre pair.
- Each PHY also has a channel insertion loss limit. Test installed links and compare the loss with the limit for the intended PHY, not only the length.
Related reading: Single-mode vs multimode fibre: OM3, OM4 and OS2 · OM4 vs OM5 fibre.