Ubiquiti UACC-DAC-QSFP28-0.5M Direct Attach Cable
Overview
The Ubiquiti UACC-DAC-QSFP28-0.5M is a 0.5-meter (1.6 feet) passive copper direct attach cable rated for 100 Gbps data rates. This cable connects QSFP28-equipped network switches, routers, and infrastructure without requiring separate transceiver modules or active optics — reducing both cost and latency in high-speed interconnections.
Key Features
- 100GBase connectivity: Delivers 100 Gbps throughput between QSFP28 ports. At this speed, even small latency differences matter; passive copper eliminates the delay introduced by active optics, critical when milliseconds affect trading floors, real-time analytics, or synchronized cluster operations.
- Short 0.5-meter run: Ideal for rack-to-rack, spine-leaf fabric, or equipment-stacking scenarios. Shorter distances reduce signal degradation and cost overhead — no need for longer cable with amplification or active retry logic when a direct attachment solves the problem.
- No transceivers or modules required: Plug the UACC-DAC-QSFP28-0.5M directly into matching QSFP28 ports. Eliminates per-port module procurement, inventory management, and swapping — one part per link instead of two.
- Passive copper construction: No power consumption, no heat generation, no firmware updates. Deploy it and it works. Reduces operational overhead in large-scale deployments where active optics require monitoring and occasional replacement.
- Supports 100GBase standard: Compatible with any networking platform adhering to 100GBase specifications and QSFP28 connector architecture. Verify your switch or router datasheet lists QSFP28 support before ordering.
When This Cable Makes Sense
Use the UACC-DAC-QSFP28-0.5M for short, high-speed links inside a data center or network closet. The 0.5-meter length fits equipment stacking, adjacent rack connections, and dense switch-to-switch topologies. If your run exceeds a few meters, active optics (DACs with retimers or optical transceivers) become necessary — passive copper works best under 3 meters.
When to Choose an Alternative
If your link distance exceeds 10 meters, switch to an active direct attach cable (DAC with inline amplification) or optical transceivers. For runs beyond 50 meters, fiber optics are standard and more cost-effective than long copper runs. Verify your switch's QSFP28 port specifications match standard 100GBase before assuming full interoperability across brands.
Integration Notes
Ubiquiti QSFP28-equipped switches and routers support this cable natively. Third-party network gear with 100GBase QSFP28 ports (Arista, Cisco, Juniper, Cumulus) will work, but always cross-reference the vendor's compatibility matrix — port behavior and PHY tuning can vary. No configuration required; connect and verify link status via the switch's management interface.
Frequently Asked Questions
Q: What's the maximum distance for this cable?
A: Ubiquiti rates the UACC-DAC-QSFP28-0.5M for 0.5 meters. Passive copper DACs typically function reliably up to 3–5 meters depending on signal quality; beyond that, signal integrity degrades. For longer runs, use active DACs or optical transceivers.
Q: Will this work with non-Ubiquiti switches?
A: Yes, provided the other device has a standard QSFP28 port and supports 100GBase. However, consult your switch manufacturer's compatibility list — some vendors qualify specific transceiver types. A passive DAC should work universally, but verification is prudent before committing to production.
Q: Does the UACC-DAC-QSFP28-0.5M require any power?
A: No. It's a passive copper cable — power is drawn from the QSFP28 ports themselves, which supply voltage to signal conditioning. No additional power supply or inline electronics needed.
Q: Can I extend this cable with adapters?
A: Not recommended. Splitters, couplers, or extension adapters will introduce impedance mismatches and further signal degradation. If you need a longer run, purchase a properly rated cable of the correct length instead.
Ted PerryPerspective based on aggregated and affiliated engineering team experience.
The Ubiquiti UACC-DAC-QSFP28-0.5M is a straightforward cable that earns its place in modern data center builds. At 0.5 meters passive copper delivering 100 Gbps, it eliminates the cost and latency penalty of active transceivers for short fabric runs. That 0.5-meter length is the key constraint — it's deliberately designed for equipment stacking and adjacent-rack topologies, not backbone runs.
Technical Highlights:
- 100 Gbps throughput: Full line-rate capacity means no bandwidth bottleneck between QSFP28 ports. Useful when you're aggregating 10x 10GbE or 25GbE circuits into a single spine link.
- Passive construction: No power draw, no retimers, no firmware — eliminates operational overhead and failure modes. In a 50-port switch, that's 50 fewer active modules to monitor and replace.
- 0.5-meter fixed length: Exact for equipment stacking. Anything longer and you'd be better served by an active DAC or optics; anything shorter is waste.
Deployment Considerations:
- Passive copper is signal-sensitive. Test link status immediately after installation. If the port shows errors or keeps dropping, signal integrity may be marginal — move to active optics or check for nearby EM sources.
- Verify your switch's QSFP28 port output voltage and PHY settings match 100GBase standard. Some Ubiquiti models have tuning knobs for DAC pre-emphasis; consult the switch datasheet.
Deploy the UACC-DAC-QSFP28-0.5M for rack-to-rack fabric consolidation in spine-leaf topologies or equipment-stacking scenarios under 2 meters. If your run length creeps beyond 1 meter, measure twice and budget for active optics as a fallback.
