Arista Networks CAB-D-8S-400G-3M Compatible 400G QSFP-DD 8 x 50G PAM4 to 8 x 50G SFP56 50G PAM4 Passive Copper Breakout Cable, 3m (10ft)

For short, high-density connections, this DAC cable combines 400G performance with a fixed 3m (10ft) cable run. It corresponds to Arista Networks CAB-D-8S-400G-3M and uses a factory-terminated passive copper link without separate optical modules or patch cords.

OEM Part Number: CAB-D-8S-400G-3MHT Part Number: CAB-D-8S-400G-3M

Product Highlights

• Compatible alternative to Arista Networks CAB-D-8S-400G-3M
• 400G connectivity at 400Gbps
• Interface configuration: QSFP-DD to 8x SFP56
• Fixed length and part number: 3m (10ft), CAB-D-8S-400G-3M
• Cable construction: Passive Breakout DAC
• Conductor specification: 28AWG
• Maximum power consumption: 0.1W (QSFP-DD End)0.1W (SFP56 Per End)
• Minimum bend radius: 39.5mm

The listed modulation format is QSFP-DD-8x 50G-PAM4SFP56-50G-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.

The QSFP-DD to 8x SFP56 configuration divides the high-speed interface into multiple lower-speed connections. Verify the upstream lane assignment, downstream port speeds and breakout setting on the host before connecting the assembly. Each branch must attach to the correct remote interface.

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.

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.

CAB-D-8S-400G-3M is the longest of 6 verified length options in this family. Compared with CAB-D-8S-400G-2.5M 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.

The rated power consumption is 0.1W (QSFP-DD End)0.1W (SFP56 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.

This assembly uses 28AWG conductors, PVC (OFNR) jacket, minimum bend radius 39.5mm. 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.

The intended application is determined by the host interface and protocol support. Listed interface and protocol references include QSFP-DD MSA, SFF-8432, IEEE 802.3bs-400GAUI-8, IEEE802.3cd-50GAUI-1, CMIS 4.0, SFF-8472. Confirm that the host firmware and port configuration support the same operating mode.

Each CAB-D-8S-400G-3M compatible cable is powered up on a suitable test interface rather than checked only for continuity. We confirm the expected identification and observe electrical continuity, link stability and diagnostic readouts. Because operating systems can apply different qualification rules by hardware revision, the intended Arista Networks platform should be included with the order.

This product is ordered as CAB-D-8S-400G-3M in 3m (10ft). Include the equipment model and software release if you would like a pre-order compatibility review. Other lengths use different part numbers and should not be substituted into the same order line.

Every CAB-D-8S-400G-3M compatible assembly undergoes link testing, compatibility verification and visual inspection. The 3m (10ft) cable is coiled without exceeding its minimum bend radius, fitted with connector protection and packed in an anti-static bag or protective tray before cartoning. Project labels and packing lists are available for volume orders.

Stock items are generally dispatched within one to three working days after order confirmation. DHL, UPS, FedEx, TNT and EMS are available for international delivery; larger consolidated orders can move by air or sea freight. Customer courier accounts and nominated forwarders are accepted.