Direct attach cables (DAC), active optical cables (AOC), and pluggable optical transceivers with fiber patching each have distinct cost, performance, and operational profiles. This guide provides a framework for choosing between them.
Direct Attach Copper Cable (DAC)
DAC assemblies integrate the transceiver module and cable into a single fixed-length assembly using twinaxial copper, available in passive (≤5m) and active (~7m) variants.
Best for: Top-of-rack to server connections, within-rack switch connections, hyper-dense GPU cluster deployments where latency and cost per port matter most.
Active Optical Cable (AOC)
AOC assemblies use the same fixed-length form factor as DAC but use optical fiber and integrated VCSEL/PIN photodetector arrays. They offer longer reach (up to 100m on OM4), lighter weight, and EMI immunity.
Best for: Fixed-length connections in the 5–100m range where structured fiber cabling is not justified.
Pluggable Transceiver + Fiber
Pluggable transceivers (SFP+, QSFP28, QSFP-DD, OSFP) connect to industry-standard fiber running through a structured cabling plant, enabling independent transceiver and fiber changes.
Best for: Distances over 100m, structured cabling environments, deployments where flexibility and reconfigurability are important.
Decision Matrix
| Distance | Recommendation |
|---|---|
| ≤3m | Passive DAC |
| 3–7m | Active DAC or AOC |
| 7–100m | AOC |
| >100m | Pluggable transceiver + structured fiber |
Contact ATL Optics for a recommendation tailored to your topology.