InfiniBand/fibre optic cable BlueOptics X2121A-05M-N-BL 0.5 m QSFP Male/Male

The BlueOptics X2121A-05M-N-BL is a 0.5 m InfiniBand/fibre optic Direct Attach Cable (DAC) with QSFP connectors on both ends. Designed for high-speed short-reach links, this passive twinax copper style cable supports up to 40 Gbit/s over a half-meter distance and is suitable for rack-to-rack or intra-rack connections in data centers and high-performance computing environments. The cable follows QSFP MSA guidelines and is built to provide stable electrical transmission for Ethernet, Fibre Channel, FCoE and InfiniBand protocols where passive QSFP-to-QSFP DACs are supported.

Advantages

This 0.5 m QSFP-to-QSFP cable offers a low-latency, low-power passive connection optimized for short distances. The cable’s 30 AWG twinax construction provides predictable signal integrity for 40GBase-CR4 type links while avoiding the need for active components. Compliance with QSFP MSA electrical and mechanical specifications ensures broad interoperability with hardware platforms that accept QSFP passive DACs. Passive design reduces power consumption and failure points compared with active optical modules, and use of quality components contributes to long service life.

Suitable for

• High-speed links between switches and routers within the same rack or adjacent racks
• Short-reach connections for storage systems and SAN environments
• InfiniBand and 40G Ethernet interconnects in HPC clusters and data centers
• Environments that require low-latency, low-power passive QSFP connections

Key specifications

• Cable type: passive twinax (DAC) with QSFP-to-QSFP connectors
• Length: 0.5 meter
• Data rate: up to 40 Gbit/s (40GBase-CR4 compatible)
• Wire gauge: 30 AWG
• Supported protocols: Ethernet, Fibre Channel, FCoE, InfiniBand (where passive QSFP DAC is supported)
• Form factor: QSFP male to QSFP male
• MSA compliance: QSFP electrical and mechanical interoperability

How to use

Connect each QSFP plug to the corresponding QSFP port on compatible network switches, routers or storage interfaces. Ensure the host hardware explicitly supports passive QSFP DACs and the chosen transmission protocol (for example, 40GBase-CR4). Handle the cable by the connector housings when routing, avoid tight bends near the connector area, and secure the cable to prevent strain on the QSFP plugs. No power or configuration is required for the cable itself; any link negotiation is handled by the connected devices.

Recommendations

Use this 0.5 m BlueOptics QSFP passive DAC for short, high-throughput interconnects inside racks or between immediately adjacent racks. Verify hardware compatibility for passive QSFP DAC support, follow manufacturer port guidelines, and test in a representative setup before full deployment to confirm link speed and protocol interoperability.