Cisco QDD-400-CU3M Compatible 400G QSFP-DD 8 x 50G PAM4 Passive Copper Twinax Cable, 3m (10ft)
The QDD-400-CU3M compatible DAC cable provides 400G connectivity for Cisco equipment over a fixed 3m (10ft) assembly. Both ends use the stated QSFP-DD to QSFP-DD arrangement. It is inspected and functionally checked before packing, with handling guidance designed to protect the connectors during installation and later service.
OEM Part Number: QDD-400-CU3MHT Part Number: QDD-400-CU3M
Product Highlights
- Compatible alternative to Cisco QDD-400-CU3M
- 400G connectivity at 400Gbps
- Interface configuration: QSFP-DD to QSFP-DD
- Fixed length and part number: 3m (10ft), QDD-400-CU3M
- Cable construction: Passive Twinax
- Conductor specification: 26AWG
- Maximum power consumption: 0.1W Per End
- Minimum bend radius: 57mm
Specifications
| HT Part Number | QDD-400-CU3M |
|---|---|
| Cisco Compatible | QDD-400-CU3M |
| Manufacturer | HT |
| Form Factor | QSFP-DD to QSFP-DD |
| Max. Data Rate | 400Gbps |
| Media | Copper |
| Cable Type | Passive Twinax |
| Cable Length | 3m (10ft) |
| Wire AWG | 26AWG |
| Minimum Bend Radius | 57mm |
| Max. Power Consumption | 0.1W Per End |
| Jacket Material | PET |
| Commercial Temperature Range | 0 to 70°C (32 to 158°F) |
| Modulation Format | 8x 50Gbps PAM4 |
| Application | 400G Ethernet |
| Protocols | IEEE 802.3cd, QSFP-DD MSA, CMIS 4.0 |
Signal and Lane Configuration
The listed modulation format is 8x 50Gbps PAM4. Both host interfaces must be configured for the same aggregate rate and lane arrangement. A connector that fits mechanically does not by itself guarantee that the remote port supports this encoding or breakout mode.
Power and Thermal Planning
The rated power consumption is 0.1W Per End. Include this load in the host-port power and thermal budget, especially in densely populated switches. Maintain front-panel clearance and do not bundle the cable so tightly that it obstructs airflow around the connectors.
Cable Construction and Routing
This assembly uses 26AWG conductors, PET jacket, minimum bend radius 57mm. These mechanical characteristics affect how the cable should be dressed behind the equipment. Avoid sharp edges, excessive ties and repeated tight bends close to the connector boots.
Network and Protocol Considerations
The intended application is 400G Ethernet. Listed interface and protocol references include IEEE 802.3cd, QSFP-DD MSA, CMIS 4.0. Confirm that the host firmware and port configuration support the same operating mode.
Passive Copper Operation
A passive DAC has no separate optical conversion stage. Its low-power, low-latency operation is useful for short equipment links, but the assembly must remain within the length and signaling mode accepted by both hosts.
Length Selection and Installation Planning
At 3m (10ft), this assembly can bridge non-aligned ports or adjacent racks while remaining a single direct-attach link. Support longer horizontal runs with suitable cable management and preserve space for cooling and future maintenance.
Position Within the Length Range
QDD-400-CU3M is the longest of 6 verified length options in this family. Compared with QDD-400-CU2.5M at 2.5m (8ft), it provides 0.5m of additional reach for a longer vertical drop, a wider rack or an adjacent-cabinet route. Confirm that the complete path requires this length, because unused slack still needs supported, bend-safe storage.
Field Installation and Maintenance
Inspect the route and both connectors before installation, then support the cable without pulling on either connector housing. During maintenance, release the latch properly rather than using the cable as a handle. Keep protection on unused ends, and if the assembly is removed for later use, coil it loosely and record its part number so the same length can be returned to service. For this assembly, the listed conductor specification is 26AWG; the minimum bend radius is 57mm; the stated power consumption is 0.1W Per End; the jacket material is PET.
Quality Assurance and Packaging
The cable and both connectors are inspected before a functional link test. Connector protection and bend-safe packing reduce handling damage during transport and storage. Customer or site labels can be added for field inventories, with different lengths separated to simplify issue and return of spare assemblies. Neutral packaging and customer-specific packing documentation are available on request.
Cisco Compatibility and Factory Testing
A field-ready cable needs both correct identification and a stable operating link. Our pre-packing check therefore includes the connectors, host recognition and link behavior. For equipment with uncertain revision history, providing the host model and software release helps identify compatibility requirements before the assembly reaches the installation site. Both connectors are examined before the operating test, which includes link stability and diagnostic indications.
Frequently Asked Questions
Is this an original Cisco cable?
No. It is an HT-manufactured compatible alternative for equipment that specifies Cisco QDD-400-CU3M.
Can different brands be connected with the same assembly?
Only where both hosts explicitly support the complete interface and compatibility arrangement. Document each end and select the appropriate brand-specific product when required.
Does this order code cover multiple lengths?
No. QDD-400-CU3M refers here to 3m (10ft). Every other verified length has a separate part number and page in the length list.
Are separate transceivers or patch leads required?
No. This is one complete direct-attach assembly. The ends are not detachable modules and should not be separated from the cable.
Ordering Information
Request the cable by its exact part number and length, and state the equipment model if compatibility confirmation is needed. Site orders can list quantities by rack or installation team. Any requested label should retain the part number so a removed or spare cable can still be identified accurately. Keep QDD-400-CU3M associated with 3m (10ft) throughout the order and receiving record.
Shipping and Lead Time
Standard configurations normally ship within one to three working days, while production quantities are confirmed with the order. International express, air cargo and sea freight can be selected according to destination and carton volume; customer courier accounts and nominated forwarders are also accepted.
