Cisco QDD-400-CU3M Compatible 400G QSFP-DD 8 x 50G PAM4 Passive Copper Twinax Cable, 3m (10ft)

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

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.

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.

Rack Layout and Service Access

Plan the managed route before removing the connector protection. The cable should reach both ports without tension while leaving enough space to release the latches and service adjacent interfaces. Support the run through the intended managers, keep the connector boots clear of sharp edges and avoid storing excess length in a tight coil behind warm exhaust air. 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.

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.

Quality Assurance and Packaging

The completed cable is inspected at both ends, functionally tested and coiled with bend-safe slack. Protective packaging keeps the latches and boots from taking impact, while optional project labels can identify the two endpoint locations for easier field service. Volume orders can include customer references on the labels and carton list.

Cisco Compatibility and Factory Testing

Compatibility is verified as part of a complete installation check: connector inspection, host identification and an operating link. The physical cable is evaluated together with the expected OEM identity, because a connector that fits is not sufficient evidence that the host will accept and operate the assembly correctly. Where supported by the host, link stability and diagnostic indications are reviewed together with the established link.

Frequently Asked Questions

Ordering Information

When requesting this assembly, include the exact part number and length together with the destination port types. For a rack installation, a simple port-to-port list helps us keep different lengths separate and allows any requested labels to correspond with the actual installation sequence. This page’s fixed configuration is 3m (10ft); another length must be quoted under its corresponding part number.

Shipping and Lead Time

Standard configurations normally ship within one to three working days, while production quantities are confirmed with the order. Delivery can be arranged by courier, air freight or sea freight, and goods may instead be handed to an appointed forwarder or shipped on the customer’s courier account.