With the rapid growth of AI computing, data centers are transforming from storage-centric architectures into compute and interconnect-driven infrastructures.
Whether for large-scale AI model training clusters or inference platforms, high-speed, low-latency connectivity has become a critical factor determining overall system performance.
Among various networking solutions, DAC (Direct Attach Copper) cables and AOC (Active Optical Cables) have become essential components for modern AI data center infrastructure.
In the past, GPU and CPU performance were considered the primary factors determining computing capability. However, in real-world AI clusters, another critical challenge has emerged:
Data transmission speed often cannot keep pace with computing performance growth.
During large-scale AI model training, such as thousands of GPUs operating in parallel, frequent parameter synchronization through All-Reduce communication is required.
If network bandwidth is insufficient or latency is too high, it can directly result in:
Reduced GPU utilization
Longer AI model training time
Increased energy consumption
This is why the concept of “Network is the Computer” is being revalidated in the AI era.
https://www.c-light.com/products/AOC_DAC/DAC.html
DAC is a low-cost, low-power short-distance interconnect solution, mainly used for connections within the same rack or between adjacent racks.
Ultra-low latency with no active optical components
Extremely low power consumption without optical-electrical conversion
Significant cost advantages
High reliability
ToR switch ↔ Server connections
Internal GPU server interconnects
Short-distance high-speed connections (≤3–5m)
10G / 25G / 100G / 400G networking
In AI clusters, DAC serves as the high-density and cost-efficient connectivity foundation.
https://www.c-light.com/products/AOC_DAC/AOC.html
AOC integrates optical transceiver components inside the cable assembly, converting electrical signals into optical signals for longer-distance transmission.
Longer transmission distance (up to 100m+)
Strong resistance to electromagnetic interference
Higher bandwidth scalability (supporting 400G, 800G, and beyond)
Suitable for complex data center cabling environments
Rack-to-rack interconnects in Leaf-Spine architectures
Cross-rack GPU cluster communication
High-speed switch-to-switch connections
AOC acts as the high-bandwidth bridge for medium-distance AI data center interconnects.
AI workloads are driving exponential growth in network bandwidth requirements.
Examples:
Large AI model training requires Tbps-level throughput
GPU-to-GPU communication requires non-blocking networks
DAC and AOC solutions support current and future high-speed standards, including 400G and 800G connectivity, making them practical solutions for next-generation AI networks.
AI data centers are already facing enormous power and thermal challenges.
High-power interconnect solutions can further increase operational costs.
Advantages:
DAC:
Almost zero additional power consumption
AOC:
Lower energy consumption compared with traditional optical transceiver + fiber solutions
At large deployment scales, this directly impacts TCO (Total Cost of Ownership).
Compared with traditional optical transceiver and fiber patch cord solutions:
DAC and AOC provide:
Integrated cable solutions
No additional configuration requirements
Fewer potential failure points
For massive AI clusters with thousands of network ports, simplified deployment and maintenance are extremely important.
Modern AI data centers commonly adopt:
Spine-Leaf network architectures
GPU POD architectures
Large-scale parallel computing clusters
These architectures share one common characteristic:
A dramatic increase in interconnection requirements.
DAC enables high-density short-distance connections, while AOC provides flexible expansion between racks.
Together, they achieve:
Optimized cost
Maximum performance
Flexible network architecture
| Solution | Cost | Power Consumption | Distance | Bandwidth | Application |
|---|---|---|---|---|---|
| DAC | Low | Very Low | Short | High | Intra-rack connectivity |
| AOC | Medium | Low | Medium | Very High | Rack-to-rack connections |
| Optical Transceiver + Fiber | High | Higher | Long | Extremely High | Backbone networks |
DAC and AOC provide the optimal balance between performance, scalability, and deployment cost for AI data centers.
As AI models continue to expand in scale, interconnect technologies are also evolving rapidly.
Future trends include:
Wider adoption of 800G DAC and AOC solutions
Silicon Photonics enabling higher integration levels
Growing interest in CPO (Co-Packaged Optics) technology
However, one thing is clear:
DAC and AOC will continue to coexist and evolve as fundamental interconnect technologies for AI data centers in the foreseeable future.
They will remain critical solutions for building efficient, scalable, and high-performance AI networking infrastructures.
Answer: DAC cables provide low latency, extremely low power consumption, and cost-effective short-distance connectivity, making them ideal for high-density GPU cluster deployments.
Answer: DAC uses copper conductors for short-distance connections with lower cost and power consumption, while AOC uses optical technology to support longer distances and higher bandwidth requirements.
Answer: Yes. Modern DAC and AOC solutions are evolving to support 400G, 800G, and future higher-speed AI networking applications.
Answer: No. Optical transceivers are mainly used for long-distance backbone connections, while DAC and AOC remain essential for short- and medium-distance AI cluster interconnects.
