40G/100G/400G/800G Transceiver-to-Cabling Map (SR4, DR4, SR8, DR8)
Each optical transceiver type expects a specific cable. SR4 and DR4 optics (40G, 100G, 200G, 400G) use an MPO-12 connector with 8 active fibers: UPC on multimode SR4, APC on single-mode DR4. 400GBASE-SR8 and 800GBASE-SR8 use an MPO-16 APC connector on OM4 with 16 fibers. 800GBASE-DR8 uses 16 single-mode fibers, either on one MPO-16 APC or on two MPO-12 APC connectors. FR4 and LR4 optics use duplex LC. For a direct point-to-point link between two parallel optics, use a Type B MPO cable with female (unpinned) ends.
This guide puts every common data center optic from 40G to 800G into one table. Use it to choose the trunk, patch cable or breakout harness before you order, and to check that your existing fiber plant will support the next upgrade.
The Master Table
Reach figures are the standard or typical module values; always confirm against your transceiver's datasheet.
| Optic | Form factor | Connector | Fibers used | End face | Fiber | Typical reach |
|---|---|---|---|---|---|---|
| 40GBASE-SR4 | QSFP+ | MPO-12 | 8 | UPC | OM3 / OM4 | 100 m / 150 m |
| 100GBASE-SR4 | QSFP28 | MPO-12 | 8 | UPC | OM3 / OM4 | 70 m / 100 m |
| 100G PSM4 (MSA) | QSFP28 | MPO-12 | 8 | APC | OS2 | 500 m |
| 200GBASE-SR4 | QSFP56 | MPO-12 | 8 | UPC | OM3 / OM4 | 70 m / 100 m |
| 400GBASE-SR4.2 (BiDi) | QSFP-DD / OSFP | MPO-12 | 8 | UPC | OM3 / OM4 / OM5 | 70 / 100 / 150 m |
| 400GBASE-SR8 | QSFP-DD / OSFP | MPO-16 | 16 | APC | OM3 / OM4 | 70 m / 100 m |
| 400GBASE-DR4 | QSFP-DD / OSFP / QSFP112 | MPO-12 | 8 | APC | OS2 | 500 m |
| 400G XDR4 / DR4+ | QSFP-DD / OSFP | MPO-12 | 8 | APC | OS2 | 2 km |
| 400GBASE-FR4 / LR4 | QSFP-DD / OSFP | Duplex LC | 2 | UPC | OS2 | 2 km / 10 km |
| 800G VR8 / 2×VR4 | OSFP / QSFP-DD800 | MPO-16 or 2× MPO-12 | 16 | APC | OM3 / OM4 | 30 m / 50 m |
| 800GBASE-SR8 / 2×SR4 | OSFP / QSFP-DD800 | MPO-16 or 2× MPO-12 | 16 | APC | OM4 | 100 m |
| 800GBASE-DR8 / 2×DR4 | OSFP / QSFP-DD800 | MPO-16 or 2× MPO-12 | 16 | APC | OS2 | 500 m |
| 800G 2×FR4 / 2×LR4 | OSFP | Dual duplex LC | 4 | UPC | OS2 | 2 km / 10 km |
Some 400G and 800G modules are sold in more than one connector version (for example MPO-16 or dual MPO-12 for the same 800G DR8 optic). The connector on the module, not the speed, decides the cable.
Reading the Code: SR, DR, FR, LR and the Number
- SR = short reach over multimode (850 nm). VR = very short reach multimode.
- DR = 500 m over single-mode, one wavelength per fiber pair.
- FR / LR = 2 km / 10 km over single-mode, usually several wavelengths multiplexed onto one duplex pair (LC).
- The number = optical lanes. 4 means 4 transmit + 4 receive fibers = 8 fibers. 8 means 8 + 8 = 16 fibers.
- .2 (as in SR4.2) = two wavelengths per fiber (bidirectional), so 4 pairs carry 8 lanes.
So any "4" parallel optic fits an 8-fiber MPO interface, and any "8" parallel optic needs 16 fibers. That is the core of the map.
MPO-12 With 8 Fibers: SR4 and DR4
An MPO-12 connector has 12 positions in one row. SR4 and DR4 optics use the outer four on each side (positions 1–4 transmit, 9–12 receive) and leave the middle four dark. That is why Base-8 cabling (8-fiber trunks and cords) has become popular: it uses every fiber you buy. See Base-8 vs Base-12 vs Base-16.
- Multimode SR4 optics have used flat UPC end faces on MPO-12.
- Single-mode DR4 optics use APC (angled) MPO-12 to control reflections. Mixing APC and UPC damages the end faces, so match the cable to the module. See APC vs UPC MPO connectors.
MPO-16 With 16 Fibers: SR8 and DR8
400GBASE-SR8, 800GBASE-SR8 and 800GBASE-DR8 have 8 transmit and 8 receive lanes. The MPO-16 connector puts all 16 fibers in one row, with a key position offset so it cannot be mated with an MPO-12. Important points:
- Current SR8 and DR8 modules use MPO-16 APC, even on multimode.
- An MPO-16 does not mate with an MPO-12; you need MPO-16 cables end to end, or a conversion harness.
- Many 800G modules instead offer two MPO-12 APC ports (often labelled 2×SR4 or 2×DR4). Each port is an independent 400G link using 8 fibers, which makes it easy to break out to two 400G switch ports.
Plan the trunk fiber count accordingly: a 144-fiber Base-8 trunk supports 18 four-lane links or 9 eight-lane (16-fiber) links. See MPO fiber count guide.
Duplex LC: FR4, LR4 and DR1
When an optic multiplexes wavelengths (FR4, LR4) or uses one lane only (100GBASE-DR, 100G FR1), the interface is duplex LC or a very small form factor connector. These links run over standard duplex single-mode patch cords and LC cassettes. See LC vs SC.
Polarity and Gender
Transceivers have pinned (male) MPO ports. So the cable plugged into a module must have a female (unpinned) connector. For a direct link between two parallel optics:
- Type B polarity (fiber position 1 maps to position 12, flipping the order) connects transmit to receive. This is the usual choice for SR4, DR4, SR8 and DR8 point-to-point.
- Through a structured system (trunk + patch cords), the total channel must still cross transmit to receive. A common method is Type B trunk with Type B cords at both ends.
For details, see MPO polarity Type A, B, C and male vs female MPO connectors.
Breakout: One Fast Port to Several Slower Ports
Parallel optics can be split:
| Breakout | Cable |
|---|---|
| 40G-SR4 → 4×10G-SR | 8-fiber MPO-12 UPC to 4× LC duplex (multimode) |
| 100G-SR4 → 4×25G-SR | 8-fiber MPO-12 UPC to 4× LC duplex (multimode) |
| 400G-DR4 → 4×100G-DR | 8-fiber MPO-12 APC to 4× LC duplex (single-mode) |
| 800G 2×DR4 → 8×100G-DR | Two 8-fiber MPO-12 APC to LC harnesses |
| 800G DR8 (MPO-16) → 2×400G-DR4 | MPO-16 APC to 2× MPO-12 APC conversion assembly (Huawellux makes these to order) |
A breakout harness or an MPO-to-LC cassette does the split. The single-lane LC side normally uses UPC; check the module. See what is an MTP-LC cassette.
Planning the Fiber Plant for the Next Generation
- Count lanes, not gigabits. 400G-DR4 and 800G-2×DR4 both use 8-fiber ports; 800G-DR8 on MPO-16 needs 16.
- Choose single-mode early for long or shared runs. DR optics reach 500 m on OS2 and the same fiber carries FR and LR.
- Use APC on single-mode MPO. All DR4/DR8 optics are APC; many new multimode 400G/800G optics are APC too.
- Check the loss budget. 400G and 800G parallel links have tight channel loss limits; see MPO insertion loss budget.
- Choose OM4 or OM5 for multimode. OM3 shortens SR4 and SR8 reach; OM5 helps SR4.2 BiDi. See OS2 vs OM3 vs OM4 vs OM5.
Huawellux Cabling for Parallel Optics
Huawellux manufactures the cables in this map:
- MPO and MTP® patch cables in 8, 12, 16 and 24 fibers (OS2 G.657.A1, OM4, OM5), each end selectable as UPC or APC and male or female, 1 m to 5 m. The 16-fiber versions suit SR8 and DR8 modules.
- MPO and MTP® trunk cables with MTP-12 or MPO-12 ends, 48, 96 and 144 fibers.
- MPO/MTP-to-LC breakout harnesses in 8 and 12 fibers, with UPC or APC LC ends, for SR4 and DR4 breakouts.
- Made to order: MPO-16 trunk cables and MPO-16 cassettes, multimode (OM4/OM5) MPO-16 APC assemblies for SR8 optics, and MPO-16 to 2× MPO-12 conversion assemblies for 800G DR8 to 2×400G-DR4 breakouts.
Huawellux's specification for MPO and MTP® assemblies (identical for both) is insertion loss ≤0.35 dB for single-mode and multimode, with return loss >60 dB single-mode (OS2, APC) and >30 dB multimode (OM3/OM4/OM5). LC and SC patch cords are listed at insertion loss ≤0.35 dB and return loss ≥50 dB (single-mode UPC), ≥60 dB (single-mode APC) and >30 dB (multimode). Every Huawellux product receives end-face visual inspection under a 400x video microscope and is tested for insertion loss (IL) and return loss (RL) before it ships. Interferometric end-face geometry (fiber height, coplanarity, end-face angle and radius) is checked by sample-based testing in standard production, and 100% interferometer testing of a batch is available on request. Dust caps are fitted on every connector, and a formal test report is available on request.
DAC, AOC or fiber? For when to use copper or active optical cables instead of transceivers with fiber, see AOC vs DAC vs fiber.
Frequently Asked Questions
What cable does 400G SR8 use?
400GBASE-SR8 uses an MPO-16 APC connector with 16 multimode fibers, reaching about 100 m on OM4. Use a female MPO-16 APC cable, Type B for a direct link.
What connector does 800G DR8 use?
800GBASE-DR8 uses 16 single-mode fibers, either on one MPO-16 APC connector or on two MPO-12 APC connectors, depending on the module version. Reach is 500 m on OS2.
Do QSFP-DD and OSFP need different cables?
No. The form factor does not decide the cable; the optic type does. A 400G DR4 module in QSFP-DD or OSFP uses the same MPO-12 APC cable.
What polarity do SR4 and DR4 links need?
For a direct point-to-point link between two modules, a Type B female-to-female MPO cable. Through a structured system, design the whole channel so transmit reaches receive.
Order the Right Cables from Huawellux
Huawellux manufactures MPO and MTP® assemblies at our factory in Shenzhen, with genuine US Conec MTP® or standard MPO connectors, in OS2, OM3, OM4 and OM5. Browse MPO patch cables, MTP/MPO trunk cables, breakout harness cables, standard fiber patch cords and fiber management enclosures.
Huawellux replies to inquiries within 24 hours. Custom orders typically take 1–5 business days to complete production, with final timing confirmed case by case in the quotation. For special/custom requirements, MOQ is 2 km of fiber length. Standard listed patch cords have no formal MOQ. The sample fee is credited against the bulk order.
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