As data centers, cloud infrastructures, and AI computing environments continue to expand, the need for high-speed interconnect solutions becomes increasingly important. Among the leading technologies for 100-gigabit Ethernet networks are QSFP28 AOC 100G cables, QSFP28 DAC cables, and QSFP28 breakout cables. Each of these cable types has its own characteristics, applications, and performance benefits, making them essential components in modern networking architecture.
This article explores all three cable types in detail to help you understand their differences, use cases, and advantages when deploying or upgrading high-speed networks.
1. QSFP28 AOC 100G Cable (Кабель QSFP28 AOC 100G)
A QSFP28 AOC 100G (Active Optical Cable) is an integrated optical cable assembly that provides a 100-gigabit link using fiber optic transmission. Unlike traditional cabling that requires separate transceivers and patch cords, Кабель QSFP28 AOC 100G AOC combines both transceivers and fiber into one ready-to-use plug-and-play unit.
Key Characteristics
Utilizes multimode fiber for high-speed data transmission
Supports link distances typically from 3 meters up to 100–200 meters
Lightweight and bend-friendly, ideal for dense data center layouts
Immune to electromagnetic interference (EMI)
Advantages of QSFP28 AOC
Extended Reach
AOC accommodates much longer distances than copper DAC cables, making it perfect for inter-rack and row-to-row connections.Excellent Signal Quality
Optical transmission guarantees stable, low-latency, and noise-free performance, even in environments with heavy electrical interference.Low Power Consumption
Pre-terminated optical engines inside the connectors require less power than pluggable transceivers.Easy Deployment
No need for testing, cleaning, or polishing optical connectors—everything is factory-installed and ready to deploy.
Ideal Use Cases
Linking switches between different rows in large data halls
Connecting servers and aggregation switches across wider distances
High-performance computing clusters
Environments where cable weight and flexibility are a priority
The QSFP28 AOC 100G cable is therefore a go-to solution for mid-range connectivity where optical performance is required without the cost of discrete transceivers.
2. QSFP28 DAC Cable (Кабель QSFP28 DAC)
A QSFP28 DAC (Direct Attach Copper) cable is a high-speed twinax cable assembly used for very short-distance 100G Ethernet connections. It features QSFP28 connectors on both ends and comes in two types: passive and active.
Passive DAC
No power required
Maximum distance: 0.5 to 3 meters
Lowest cost and lowest latency
Active DAC
Includes signal conditioning electronics
Supports up to 5–7 meters
Slightly more expensive but improves signal integrity
Advantages of QSFP28 DAC
Ultra-Low Latency
Since copper transmission introduces almost no propagation delay, DAC is preferred in latency-sensitive applications.Cost Efficiency
DAC is the cheapest option for 100G connectivity because it requires no optics or fiber.High Reliability
DAC cables are robust, durable, and less prone to damage than fiber optic cables.Plug-and-Play Simplicity
No optical maintenance, no cleaning, and no special handling required.
Typical Use Cases
Switch-to-server connections in the same rack
Short links between adjacent top-of-rack (ToR) switches
Large-scale cloud deployments seeking low cost and maximum density
AI/ML clusters requiring ultra-low latency for GPU-GPU communication
QSFP28 DAC cables are the most economical and fastest solution for short-distance connections inside racks or across a few meters.
3. QSFP28 Breakout Cable (Кабель QSFP28 Breakout)
A QSFP28 breakout cable splits a single 100G QSFP28 port into several lower-speed interfaces—most commonly 4×25G SFP28. Breakout cables are available in both DAC and AOC formats.
How Breakout Cables Work
A QSFP28 module uses four parallel 25G lanes internally. A breakout cable separates these lanes and maps them individually to four SFP28 connectors, enabling multiple devices to share one 100G port.
Common Configurations
100G QSFP28 → 4×25G SFP28 (most popular)
100G QSFP28 → 2×50G (less common)
Advantages of QSFP28 Breakout Cables
Port Efficiency
Maximize port usage on high-speed switches by enabling multi-device connectivity through a single port.Flexible Deployment
Supports mixed networks where both 25G and 100G devices operate together.Cost-Effective Scalability
No need to replace all equipment with 100G hardware; breakout cables allow gradual upgrades.Space Optimization
Useful in high-density racks where additional fiber or copper runs are limited.
Typical Use Cases
Connecting 100G uplink switch ports to four 25G server NICs
Expanding network capacity without adding more switch hardware
ToR deployments in enterprise and cloud data centers
Migration from 25G to 100G while maintaining backward compatibility
Breakout cables are essential for high-density modern data center designs that require flexible and scalable connectivity.
Comparison Overview
Feature | QSFP28 AOC 100G | QSFP28 DAC | QSFP28 Breakout |
Transmission Medium | Fiber optic | Copper | Fiber or copper |
Distance | 3–200 m | 0.5–7 m | Depends on type |
Cost | Moderate | Lowest | Moderate |
Use Case | Inter-rack | In-rack | 100G → 4×25G fan-out |
EMI Resistance | Excellent | Limited | Excellent (AOC) |
Conclusion
QSFP28 AOC 100G, QSFP28 DAC, and QSFP28 breakout cables each offer unique advantages for 100G networking environments. Choosing the right cable depends on distance requirements, budget, equipment compatibility, and desired performance.
AOC is ideal for medium-distance optical connections requiring flexibility and excellent signal integrity.
DAC is the most cost-effective and lowest-latency solution for short connections inside racks.
Breakout cables provide unmatched flexibility by allowing one 100G port to support multiple 25G endpoints.
By understanding the capabilities and best-fit scenarios of each cable type, network architects can design scalable, efficient, and high-performance data center infrastructure ready for today’s and tomorrow’s bandwidth demands.
