What Are DAC and AOC?
Both connect switches/servers in data centers but use different technologies:
- DAC (Direct Attach Copper): Passive copper cable with SFP+/QSFP+ connectors
- AOC (Active Optical Cable): Fiber optic cable with integrated transceivers
DAC Cables
Advantages
- Lowest cost: No transceivers needed — 50-70% cheaper than optics
- Zero power: Passive design consumes no electricity
- Ultra-low latency: <1ns — ideal for HPC and trading
- Plug-and-play: No configuration, hot-swappable
Limitations
- Distance: Max 7-10m (signal degradation over copper)
- Thickness: Less flexible than fiber, harder to route
- EMI: Susceptible to electromagnetic interference
When to Use DAC
- Top-of-rack (ToR) to server connections (<5m)
- High-frequency trading environments
- Budget-conscious data centers
- Where power consumption is critical
AOC Cables
Advantages
- Longer reach: Up to 100m (vs 10m for DAC)
- Lightweight: 30-50% lighter than DAC — easier cable management
- EMI immune: Fiber is unaffected by electromagnetic interference
- Better bend radius: More flexible for dense racks
Limitations
- Higher cost: Integrated electronics add expense
- Power draw: ~1W per end (minimal but not zero)
- Repair: Cannot be field-terminated like discrete fiber
When to Use AOC
- Middle-of-row (MoR) or end-of-row (EoR) connections
- Noisy electrical environments
- Weight-sensitive installations (aerospace, mobile)
- Where flexibility matters more than absolute cost
Speed Options
| Type | Speed | Distance | Use Case |
|---|---|---|---|
| SFP+ DAC | 10G | 1-10m | Server to ToR |
| SFP28 DAC | 25G | 1-5m | 25G server connections |
| QSFP+ DAC | 40G | 1-7m | Aggregation layer |
| QSFP28 DAC | 100G | 1-3m | Core switching |
| QSFP28 AOC | 100G | 1-100m | Longer data center links |
BHL Networks DAC/AOC Range
Passive DAC cables from 10G to 100G in 1m, 3m, 5m, and 7m lengths. AOC cables from 10G to 100G up to 100m. All cables tested for BER compliance and MSA compatibility with Cisco, Juniper, Arista, and Dell switches.