QNAP CAB-DAC15M-Q28 QSFP28 100GbE Direct Attach Twinax Cable
Overview
The CAB-DAC15M-Q28 is a QSFP28 100GbE passive direct attach copper (DAC) twinaxial cable in a 1.5-meter length. DAC cables eliminate the cost and power draw of active optical transceivers on short-reach switch-to-server or switch-to-switch links inside the same rack or adjacent racks — the 1.5m length is the right choice when your top-of-rack switch sits within a single rack unit of the target device. Passive copper means no signal conversion electronics, lower latency, and no per-end transceiver licensing fees on platforms that enforce them.
Compatibility
Designed for use with QNAP network switches and NAS appliances that carry QSFP28 100GbE ports, including the QSW-series 100GbE network switches and high-end TVS/TES NAS units with expansion card slots populated by QNAP QSFP28 adapters. The QSFP28 form factor is also broadly compatible with third-party 100GbE infrastructure — Cisco, Arista, Mellanox/NVIDIA, and Juniper QSFP28 ports generally accept DAC cables to MSA specification, though compatibility should be confirmed against each platform's interoperability matrix before deployment. Both ends use the same QSFP28 connector, making the cable symmetric and direction-independent. For longer runs or inter-rack distances beyond 3–5 meters, an active optical cable or SR4 transceiver pair is the appropriate alternative; passive DAC copper is not viable past roughly 5 meters at 100G.
Installation Notes
Seat each QSFP28 connector firmly until the latch clicks — a partially seated DAC is the most common cause of link-down at 100G. No tools required. Bend radius: avoid sharp bends within 50mm of the connector body, which can stress the copper conductors and cause intermittent errors under vibration. Because this is a passive cable, no firmware or driver support is needed beyond standard QSFP28 port bring-up. Verify that both ends are running at the same FEC (Forward Error Correction) mode — mismatched FEC settings will prevent link establishment on 100G ports even when the cable is seated correctly.
