Cisco QDD-400-CU Compatible 400G QSFP-DD 8 x 50G PAM4 Passive Copper Twinax Cable

The QDD-400-CU compatible cable series is intended for Cisco equipment requiring a 400G DAC connection. Its QSFP-DD to QSFP-DD configuration supports a passive copper twinax connection without separate optical modules or fiber patch cords, while the verified source lengths listed below make length selection explicit.

Series Part Number: QDD-400-CUHT Part Number: QDD-400-CU

Product Highlights

• HT-manufactured compatible alternative for Cisco QDD-400-CU
• 400G aggregate connectivity at 400Gbps
• Interface configuration: QSFP-DD to QSFP-DD
• Passive Twinax / Copper
• Length configurations covered: 0.5m (2ft), 1m (3ft), 1.5m (5ft), 2m (7ft), 2.5m (8ft) and 3m (10ft)
• Conductor specification: 30AWG
• Power consumption: 0.1W Per End
• Operating temperature: 0 to 70°C (32 to 158°F)

• QDD-400-CU0.5M
• QDD-400-CU1M
• QDD-400-CU1.5M
• QDD-400-CU2M
• QDD-400-CU2.5M
• QDD-400-CU3M

Passive DAC assemblies are normally used for short switch-to-switch, switch-to-server and rack-adjacent links. They draw very little power and avoid separate optical components, but the selected length must remain within the host and cable specification.

The QSFP-DD to QSFP-DD interface and 400G data rate must match the equipment at both ends. The source application is listed as 400G Ethernet. For breakout versions, confirm the lane mapping and the speed of every downstream port; matching connector shapes alone does not establish interoperability.

The assembly is configured for equipment that recognizes the QDD-400-CU series. Before shipment, we check connector identification, link establishment and electrical link stability, signal integrity and diagnostic readouts. Host hardware and firmware revisions can affect third-party cable acceptance, so customers can provide the switch, server or accelerator model and software release for a pre-order compatibility review.

This series is ordered by the base HT part number QDD-400-CU plus length and compatibility requirement. Available source configurations documented on this page are 0.5m (2ft), 1m (3ft), 1.5m (5ft), 2m (7ft), 2.5m (8ft) and 3m (10ft); other lengths can be discussed with the factory with each length-specific OEM reference reviewed under its own product configuration.

Every DAC assembly undergoes continuity and link testing, compatibility verification and a visual inspection of both connector ends. Cables are coiled without exceeding their minimum bend radius, fitted with connector protection and packed in anti-static bags or protective trays before cartoning. Project labels and packing lists are available for volume orders.

Standard configurations normally ship within one to three working days. Worldwide courier, air freight and sea freight options are available, and shipments can also be sent on your own courier account or delivered to an appointed forwarder.