DAC cable CBO QSFP28-4SFP28-DAC-3M 3 m passive direct-attach for QSFP28 to 4×SFP28

Passive DAC cable CBO QSFP28-4SFP28-DAC-3M is a 3 meter direct-attach copper assembly that breaks out a single QSFP28 port into four SFP28 ports. It is designed for short-reach, high-speed interconnects in data centre topologies where low latency and compact cabling are required. The cable provides a fixed, low-loss connection between compatible QSFP28 and SFP28 devices without the need for external power or optical transceivers.

Advantages

This passive DAC delivers low latency and predictable signal behaviour for 100G to 4×25G breakout applications. The 3 m length is suitable for rack-to-rack or within-rack connections while avoiding the cost and complexity of transceivers and fibre patching. As a direct-attach copper assembly, it requires no additional power source and supports straightforward plug-and-play installation in QSFP28 and SFP28 ports that accept passive DACs.

Suitable for

• Breaking out a 100G QSFP28 port into four 25G SFP28 ports for server or switch connectivity
• Short-reach connections within racks or between adjacent racks in data centres
• High-density switch-to-server or switch-to-switch links where cable management and low latency matter
• Environments where optical transceivers are not required or where cost-effective copper interconnects are preferred

Key specifications

• Form factor: QSFP28 to 4×SFP28 breakout direct-attach cable
• Type: Passive copper assembly (direct-attach cable)
• Length: 3 m
• Supported data rates: 100G (QSFP28) to 4×25G (SFP28) breakout operation
• Latency: Low, fixed propagation delay typical of direct-attach copper
• Compatibility: Devices with QSFP28 and SFP28 ports that accept passive DACs
• Installation: Plug-and-play, no external power or transceivers required

How to use

Insert the QSFP28 connector into the QSFP28 port on the source device and plug the four SFP28 connectors into the corresponding SFP28 ports on the destination device(s). Ensure both devices support passive DAC connections and that port configurations match the intended breakout mapping. Handle the cable by the connector housings to avoid strain on the cable conductors and route the assembly to maintain proper bend radii and cable management within the rack.

Recommendations

For reliable performance, verify device compatibility and firmware support for 100G-to-4×25G breakout mode before deployment. Use the 3 m length for short-reach interconnects; avoid excessive bending and secure connectors to prevent accidental disconnection. Where electrical isolation or longer distances are required, consider optical transceivers and fibre cabling instead.