400G QSFP-DD to 4x 100G QSFP56 Passive DAC Cable Specifications
| Link role | A QSFP-DD uplink to 4x QSFP56 fan-out link for port consolidation, staged speed migration, and high-density server or accelerator attachment. |
|---|---|
| Endpoint form factor | QSFP-DD to 4x QSFP56; lane breakout must be enabled on the host port |
| Aggregate data rate | 400G |
| Lane / channel detail | 400G aggregate split across the endpoint legs shown in the product name |
| Length guidance | Up to 3 m |
| Power approach | Passive cable assembly; no active optical engine |
| Standards / management | Applicable MSA and electrical-interface requirements per datasheet |
| Cable construction | Varies by length and assembly option; copper twinax assembly |
| Operating temperature | 0℃ to 70℃ |
| Configuration status | Standard and custom options must be confirmed in the quotation and approved BOM |
Search terminology for this configuration includes 400G to 100G DAC cable, 400G fanout copper cable, 4x100G from QSFP-DD. These phrases describe the same purchase task only when the endpoint form factor, breakout ratio and lane map, and ordered length match this page.
Standards context: Ethernet Alliance technology overview.
When to Use This 400G Passive DAC
- Use it for fan-out links with QSFP-DD to 4x QSFP56 endpoints when the routed path stays within up to 3 m.
- Choose passive copper when low cable power and simple installation matter more than reach or cable diameter.
- Confirm that the source port supports the required breakout mode and that each leg maps to the intended downstream port.
Compatibility and Acceptance Checklist
- Confirm the connector at each end: QSFP-DD to 4x QSFP56.
- Confirm the required aggregate rate and host lane mode: 400G aggregate split across the endpoint legs shown in the product name.
- Measure the routed path, not the straight-line rack distance; the current datasheet states up to 3 m.
- Send switch/NIC part numbers and firmware versions for coding review; no platform-specific compatibility is assumed without validation.
- Provide the lane-to-leg map, leg labels, and branch length before production approval.
- Enable and validate host breakout mode before acceptance testing each downstream leg independently.
- Specify commercial or industrial temperature requirements and the requested jacket/label/packaging details.
- At receipt, verify labels and part numbers, inspect latches and cable jackets, then test the complete link at the intended data rate.
1 Differential Insertion Loss (SDD21 Max.)
| AWG / Length | 1.25 GHz | 2.5 GHz | 5.0 GHz | 7.0 GHz | 10 GHz | 12.89 GHz |
|---|---|---|---|---|---|---|
| 30 AWG (1 m) Max | 4.5 dB | 5.4 dB | 6.3 dB | 7.5 dB | 8.5 dB | 10.5 dB |
| 30/28 AWG (3 m) Max | 7.5 dB | 9.5 dB | 12.2 dB | 14.8 dB | 18.0 dB | 21.5 dB |
| 26 AWG (3 m) Max | 5.7 dB | 7.2 dB | 9.9 dB | 11.9 dB | 14.1 dB | 16.5 dB |
| 26/25 AWG (5 m) Max | 7.8 dB | 10.0 dB | 13.5 dB | 16.0 dB | 19.0 dB | 22.0 dB |
Ordering Options
| Part Number | Description | Length | AWG | Jacket | Length Tolerance |
|---|---|---|---|---|---|
| BWN-DAC-QSFPDD-4QSFP56-400G-0.5M | 400G QSFP-DD to 4xQSFP56 Passive DAC | 0.5 m | 30 | PVC / LSZH | +/-15 mm |
| BWN-DAC-QSFPDD-4QSFP56-400G-01M | 400G QSFP-DD to 4xQSFP56 Passive DAC | 1 m | 30 | PVC / LSZH | +/-25 mm |
| BWN-DAC-QSFPDD-4QSFP56-400G-1.5M | 400G QSFP-DD to 4xQSFP56 Passive DAC | 1.5 m | 30 | PVC / LSZH | +/-30 mm |
| BWN-DAC-QSFPDD-4QSFP56-400G-02M | 400G QSFP-DD to 4xQSFP56 Passive DAC | 2 m | 28 | PVC / LSZH | +/-35 mm |
| BWN-DAC-QSFPDD-4QSFP56-400G-2.5M | 400G QSFP-DD to 4xQSFP56 Passive DAC | 2.5 m | 28 | PVC / LSZH | +/-35 mm |
| BWN-DAC-QSFPDD-4QSFP56-400G-03M | 400G QSFP-DD to 4xQSFP56 Passive DAC | 3 m | 28 | PVC / LSZH | +/-45 mm |
| BWN-DAC-QSFPDD-4QSFP56-400G-xxM | 400G QSFP-DD to 4xQSFP56 Passive DAC | Custom | Custom | – |
Common Procurement Objections
Will it work in my switch or NIC?
Form factor and standards alignment are necessary but not sufficient. Send the exact host model, firmware, port mode, length, and coding requirement for a compatibility review.
Which length should I order?
The current datasheet lists up to 3 m. Measure the routed path, include a controlled service loop, and avoid ordering unnecessary slack.
Should I use AOC instead?
Use an ACC when a copper route exceeds the practical passive budget but remains short. Use an AOC when the route needs more distance, a lighter cable body, or EMI immunity.
Can BWNFiber customize the assembly?
Datasheet ordering tables include standard and/or custom entries. Submit the endpoint, length, label, jacket, coding, temperature, packaging, and quantity requirements for feasibility confirmation.
Related High-Speed Cable Options
Request a Configuration Review
Send endpoint models, firmware, port mode, length, quantity, temperature, labeling, packaging, and acceptance requirements. BWNFiber can return a proposed cable code and BOM for review.
