100G network: find the right QSFP28 solution in 30 seconds
DAC, AOC, SR4 or LR4? The choice depends solely on the distance to cover. This visual guide shows you the 3 typical situations and the products to order — compatible with Cisco, Arista, Mellanox, HPE, Juniper.
What distance do you need to cover?
Each 100G solution matches a specific installation distance. Click on your situation to see details and the products to order.
Situation 1 — Intra-rack
Server ↔ switch in the same rack. DAC copper (≤ 5m) or AOC fibre (≤ 100m): a single cable, zero separate transceiver.
Situation 2 — Inter-rack
Two switches in the same server room. QSFP28 SR4 + MPO/MTP cable OM3/OM4: standard data centre architecture.
Situation 3 — Campus / DCI
Inter-building, Data Centre Interconnect. QSFP28 LR4 + OS2 single-mode fibre: long-term investment for critical infrastructure.
Quick comparison of the 4 solutions
| Solution | Distance | Cabling | Ideal for | Products |
|---|---|---|---|---|
| DAC copper | ≤ 5m | Direct passive copper | Entry level | QSFP28 DAC 100G → |
| AOC active fibre | ≤ 100m | Integrated active fibre | Flexibility | QSFP28 AOC 100G → |
| QSFP28 SR4 + MPO | ≤ 100m | MPO/MTP OM3 or OM4 | Data centre standard | QSFP28 SR4 → + MPO cable → |
| QSFP28 LR4 + OS2 | up to 10km | OS2 LC Duplex single-mode | 💎 Premium | QSFP28 LR4 → + OS2 fibre → |
Situation 1 — Direct intra-rack connection
Use case: connect a server to a 100G switch in the same rack. The cheapest solution, zero separate transceiver — a single integrated cable.
Passive copper, zero optical latency, no active power. The cheapest for very short distances.
View the DAC QSFP28 →
Fibre with integrated transceivers, up to 100m. Lighter and more flexible than copper over long reach.
View the AOC QSFP28 →Situation 2 — Inter-rack server room
Use case: link two racks or two switches in the same server room. Distance ≤ 100m over OM3/OM4 multimode fibre with MPO connector. Standard data centre architecture.
The most common top-of-rack architecture in data centres: one SR4 transceiver on each side + a 12-fibre MPO cable between them.
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×2
QSFP28 SR4 — Ref 21161100G SR4 MPO transceiver, 850nm, 100m OM4
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×1
MPO OM3 cable — Ref 6759MPO female / female, 12 fibres, OM3 (≤ 70m)
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OR
MPO OM4 cable — Ref 19322High density, up to 100m
Situation 3 — Long distance / campus backbone
Use case: inter-building, Data Centre Interconnect (DCI) or campus backbone. Distance up to 10km over OS2 single-mode fibre with LC Duplex connector.
Point-to-point architecture between two remote sites. OS2 single-mode fibre is the most future-proof infrastructure: it also supports upcoming 400G and 800G evolutions.
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×2
QSFP28 LR4 — Ref 21164100G LR4 LC transceiver, 1309nm, 10km OS2
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×1
OS2 LC Duplex fibre cableSingle-mode 9/125μm, custom length
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ALT
QSFP28 ER4 — Ref 2116540/80km version for very long distance
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ALT
QSFP28 BiDi — Ref 16616A single fibre instead of two (cabling savings)
FAQ — 100G data centre network
1DAC, AOC or transceiver + fibre: what is the real difference?
- DAC: passive copper up to 5m — the cheapest, zero optical latency, no active power.
- AOC: fibre with integrated transceiver, up to 100m — lighter and more flexible than copper over long reach.
- Transceiver + separate fibre cable: hot-pluggable, individually replaceable — best for future-proof infrastructure and longer distances.
2Which fibre for the QSFP28 SR4 100G?
3Which switches are your QSFP28 modules compatible with?
4Can you mix transceiver brands in the same switch?
service unsupported-transceiver command disabled).5How do you test the optical quality of a 100G transceiver?
show interface transceiver command (Cisco/Arista) or equivalent displays TX/RX power in real time. Our modules also report temperature and supply voltage.
