BlueOptics passive 400GBASE-CR8 QSFP-DD to 2×200GBASE-CR4 QSFP56 DAC breakout cable, 1 m, AWG26 (R8M51A-BL)

The BlueOptics passive 400GBASE-CR8 QSFP-DD to 2×200GBASE-CR4 QSFP56 DAC breakout cable, 1 m, AWG26 is a short-reach copper direct attach cable designed to split a single 400G QSFP-DD interface into two independent 200G QSFP56 links. Built for data centre and network aggregation environments, this 1-metre passive DAC provides a compact, low-latency connection option for high-density switches, server uplinks and equipment interconnects where 400G-to-2×200G breakout functionality is required.

Advantages

The passive construction and AWG26 conductor provide reliable signal integrity for short-reach connections while avoiding the need for transceivers in each port. The QSFP-DD to QSFP56 breakout format supports conversion of a single 400G port into two 200G links without active components, reducing power consumption and simplifying cabling. At one metre length the cable is suitable for top-of-rack and adjacent-rack connections, offering a compact, cost-effective option for dense network deployments.

Suitable for

• High-density switch-to-switch links in data centres
• Server uplinks requiring breakout from 400G to two 200G ports
• Network aggregation and spine-leaf topologies with QSFP-DD and QSFP56 ports
• Short-reach copper connections in rack and cabinet environments

When it may not be suitable

This passive DAC is intended for short-reach connections and is not suitable for long-distance links or runs that exceed the specified one-metre length. Because it is a passive direct attach cable, it does not include active signal conditioning or optical transceivers and therefore is not appropriate where optical fibre connections or active retiming are required.

Key specifications

• Cable type: Passive direct attach copper breakout cable
• Interface: QSFP-DD (400GBASE-CR8) to 2 × QSFP56 (200GBASE-CR4)
• Length: 1 metre
• Conductor size: AWG26
• Application: Short-reach data centre and rack interconnects
• Latency: Low (passive copper link)

How to use

Insert the QSFP-DD end into the 400G-capable port on the source switch or device and insert each QSFP56 end into the corresponding 200G ports on the target devices. Ensure both ends are fully seated and latched according to the equipment manufacturer’s guidance. Verify link status on connected devices and configure network interfaces as required for 200G operation. Handle the cable by the connector housings to avoid stress on the contacts and keep the cable within the recommended bend radius during installation.

What to consider before purchase

• Confirm that both source and target equipment support the QSFP-DD and QSFP56 interfaces and the required 400G-to-2×200G breakout mode.
• Verify that a 1-metre passive copper link meets your distance and environmental requirements.
• Check switch firmware and vendor compatibility lists for supported direct attach breakout cables.

Usage recommendations

Use this AWG26 passive DAC for short, high-density connections within racks or between adjacent racks where low latency and minimal power draw are priorities. Keep the cable tidy within cable management channels and avoid tight bends to maintain signal performance.