Cisco QDD-400-CU2.5M Compatible 400G QSFP-DD 8 x 50G PAM4 Passive Copper Twinax Cable, 2.5m (8ft)

Product Highlights

• Compatible alternative to Cisco QDD-400-CU2.5M
• 400G connectivity at 400Gbps
• Interface configuration: QSFP-DD to QSFP-DD
• Fixed length and part number: 2.5m (8ft), QDD-400-CU2.5M
• Cable construction: Passive Twinax
• Conductor specification: 26AWG
• Maximum power consumption: 0.1W Per End
• Minimum bend radius: 57mm

Specifications

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

The 2.5m (8ft) version is useful when a two-metre run would leave insufficient working slack. Before installation, check the complete horizontal and vertical path so that QDD-400-CU2.5M reaches both ports without tension at either connector.

Position Within the Length Range

QDD-400-CU2.5M occupies the middle of this family between QDD-400-CU2M at 2m (7ft) and QDD-400-CU3M at 3m (10ft). It adds 0.5m over the shorter option for extra routing clearance, while the next longer version adds another 0.5m. Measure the managed path and choose this version when its reach is sufficient without creating the slack associated with the longer assembly.

High-Density Rack Integration

In a densely populated rack, connector access and airflow are part of the link design. Choose the shortest length that follows the managed path comfortably, avoid tight bundles around the connector housings and preserve room for latch operation. Where power consumption is listed, include every populated interface in the host thermal budget rather than assessing a single cable in isolation. 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

Each assembly receives a visual connector inspection and functional link check before it is coiled and protected. Packaging is selected to avoid compressing the cable into a tight bundle, and optional rack-based labels help maintain an orderly installation when many identical interfaces are populated together. Volume orders can include customer references on the labels and carton list.

Ordering Information

Provide the exact part number, length, quantity and target interface density. For multi-rack projects, list each length separately and identify any preferred carton grouping. Host model and software information can be included for a compatibility review before production or dispatch. Quantity and any labeling instructions should be attached specifically to QDD-400-CU2.5M.

Cisco Compatibility and Factory Testing

The assembly is evaluated for host recognition and stable link operation, with diagnostics checked where the interface provides them. This approach verifies more than electrical or optical continuity. Exact platform and firmware information remains valuable in high-density deployments because port mode and qualification policy can differ within the same connector family. The check includes link stability and diagnostic indications, followed by a final inspection of both ends.

Frequently Asked Questions

Shipping and Lead Time

Standard configurations normally ship within one to three working days, with production quantities confirmed at order stage. 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.