DAC cable CBO QSFP28 to 4×SFP28 passive, 3 m

BlueOptics DAC cable CBO QSFP28 to 4×SFP28 passive, 3 m is a direct-attach copper assembly that converts a single QSFP28 port into four SFP28 ports over a single 3-meter twinax link. It supports 25Gbps per lane and 100Gbps aggregate speeds for short-range interconnections in racks and between adjacent racks. The passive design eliminates active electronics in the cable, delivering low latency and reduced power consumption while providing a cost-effective solution for high-density switch-to-switch or switch-to-server links in data centre environments.

Advantages

The passive QSFP28 to 4×SFP28 DAC offers reliable electrical performance with minimal signal processing, ensuring stable 25/100Gbps links without the need for transceivers. Its 3 m length is suited to short-reach top-of-rack and middle-of-row connections, simplifying cable management and reducing heat and power draw compared with active or fiber-based alternatives. The integrated multiport breakout reduces port adapter requirements and supports high-density deployments where space and power efficiency are priorities.

Suitable for

• Short-range switch-to-switch connections within a rack or between adjacent racks
• Connecting QSFP28 ports to multiple SFP28 server or NIC ports
• High-density top-of-rack aggregation and spine-leaf fabric links
• Environments prioritising low latency and reduced power consumption

Key specifications

• Cable type: passive direct-attach copper (DAC) twinax
• Connector configuration: QSFP28 (one end) to 4×SFP28 (other end)
• Supported data rates: up to 25Gbps per lane, 100Gbps aggregate
• Length: 3 metres
• Typical use: short-reach data centre interconnects, top-of-rack and adjacent rack connections
• Physical: compact, shielded twinax construction suitable for high-density deployments

How to use

Insert the QSFP28 plug into the QSFP28 port on the switch or device and insert each SFP28 connector into the target SFP28 ports on servers, NICs or other switches. Ensure both ends are fully seated and that the host devices are configured for the intended link speed and breakout mode if required. No external power or configuration is required for the cable itself; link negotiation and speed settings are handled by the connected equipment. Handle the cable by the connectors and avoid excessive bending radii to maintain signal integrity.

Recommendations

Use this passive DAC for short-distance, high-bandwidth links where low latency and power efficiency are important. Verify switch compatibility with passive DAC assemblies and enable proper breakout or port mapping on devices when connecting a single QSFP28 to multiple SFP28 interfaces. Maintain tidy routing in dense racks and avoid sharp bends to preserve performance and longevity.