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

Passive copper DAC cable CBO QSFP28 to 4×SFP28 3m from BlueOptics provides a fixed-length, low-latency electrical connection for high-speed short-reach links. The assembly converts a single QSFP28 port into four independent SFP28 lanes, enabling 25GbE or 100GbE infrastructure segmentation without active transceivers or external power. With a 3 meter copper direct-attach format, this cable is intended for server-to-switch and switch-to-switch interconnects inside racks and data centers where reliable, low-cost short-distance connectivity is required.

Advantages

The passive DAC design delivers minimal latency and stable signal performance without the need for power or heat-dissipating electronics. Fixed 3 m length simplifies cable management and planning in standard rack deployments. The breakout functionality from QSFP28 to four SFP28 ports allows flexible port utilization and cost-effective migration paths between 25GbE and 100GbE equipment. Being a copper assembly, it removes the need for separate optical transceivers for short links and reduces component count.

Suitable for

• Server-to-switch short-reach connections within a rack or adjacent racks
• Switch-to-switch aggregation links in top-of-rack and middle-of-row deployments
• Migration from 100GbE uplinks to multiple 25GbE endpoints
• Environments where low latency and deterministic electrical links are required

Key specifications

• Connector type: QSFP28 (one end) to 4 × SFP28 (other end)
• Media: Passive copper direct-attach
• Length: 3 meters fixed
• Data rates supported: up to 100GbE aggregated or 25GbE per SFP28 lane
• Latency: minimal passive electrical latency suitable for short-reach applications
• Power: no external power required
• Typical use environment: rack-mounted data centers and network equipment rooms

How to use

Install the DAC by firmly seating the QSFP28 plug into the QSFP28 port of the upstream device and the four SFP28 connectors into the downstream SFP28 ports. Ensure devices are powered down or ports are administratively disabled if recommended by the equipment vendor before insertion. Verify link lights and host interface status after physical connection, then enable or configure the ports in the network equipment as required for the intended VLANs and speeds.

Recommendations

Route the cable to avoid sharp bends and maintain manufacturer-recommended bend radius. Use the 3 m fixed length for short intra-rack or adjacent-rack links; for longer distances, consider active copper or optical solutions. Confirm compatibility with switch and server port firmware or vendor compatibility lists to ensure full lane negotiation and expected performance.