CBO DAC Cable BlueLAN QSFP28 to 4×SFP28 passive, 3 m

The CBO DAC Cable BlueLAN QSFP28 to 4×SFP28 passive, 3 m is a passive direct-attach copper (DAC) assembly designed to link a single QSFP28 port to four SFP28 ports over a short distance. This 3-metre cable provides a fixed, low-latency electrical connection without the need for separate optical transceivers, making it suitable for high-density networking environments such as top-of-rack switches, servers and storage systems where reliable short-reach interconnects are required.

Advantages

The passive DAC design delivers low latency and high signal integrity for short-reach links while avoiding the additional cost and power consumption of active optics. By combining one QSFP28 connector with four SFP28 connectors, the cable enables flexible port mapping and efficient use of switch port density. The 3 m length balances cable management in racks and typical distances between adjacent devices in data centre and enterprise wiring closets.

Suitable for

• Interconnecting top-of-rack switches to aggregation switches or servers
• Linking high-density switch blades to server or storage chassis
• Short-reach connections in data centres and server rooms
• Cost-sensitive environments that require low-power, direct electrical links

Key specifications

• Connector types: QSFP28 (one end) to 4 × SFP28 (other end)
• Cable type: passive direct-attach copper (DAC)
• Length: 3 metres
• Supported data rate: compatible with 25G per SFP28 lane and QSFP28 breakout operation
• Form factor: breakout cable for one-to-four port mapping
• Typical use: short-reach electrical interconnects within racks

How to use

Insert the QSFP28 connector into the QSFP28 port of the host device and insert each SFP28 connector into the corresponding SFP28 ports of the remote device, ensuring correct orientation and secure latching. Confirm that both connected devices support passive DAC breakout operation and the required link speeds (for example 25G per lane). After physical installation, verify link status and speed through the device management interfaces and adjust port configuration if necessary to enable the desired breakout mode.

Recommendations

Use this passive DAC cable for short-reach, high-density connections inside racks or between adjacent racks. Avoid tight bends and mechanical stress; maintain minimum bend radius recommended for copper DAC assemblies and secure cables to prevent strain on connectors. For longer distances or environments requiring electrical isolation, consider optical transceivers and fibre cabling instead.