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What's the difference between a DAC and an AOC?
Knowledge Base + 2024.01.12

What is a DAC cable?

DAC cable is a copper-based cable that connects two networking devices with SFP or QSFP connectors. It is designed for short-range data transmission, typically within a data center or rack-level communication. The maximum transmission distance of a DAC cable is generally limited to 7 meters. DAC cables, also known as twin axial cables, can transmit data at high speeds of up to 40 Gbps.

What is an AOC cable?

An AOC cable, on the other hand, utilizes fiber optic technology for data transmission. It employs a similar design as a DAC cable but uses fiber optic instead of copper wire. The AOC cable has an optoelectric transceiver on the cable ends that converts the electrical signals into optical signals and then sends them over the fiber. AOC cable typically offers a higher transmission distance of up to 100 meters or more and can transmit at higher speeds of up to 400 Gbps.

What is the difference between DAC and AOC?

AOC cable and optical fiber are both common network transmission media, but they have obvious differences in performance, usage and price. In this paper, we will introduce the following aspects of the AOC cable and fiber optic differences in detail, and provide their respective application scenarios to help readers better understand and select the appropriate network transmission medium.

1. Working principle and structure: AOC cable (Active Optical Cable) is a fiber optic transmission cable with integrated optics and electronic chip, which transmits data by converting optical signals into electrical signals. The optical fiber is a medium for signal transmission using the principle of refraction and reflection of light.

2. Transmission distance and speed: AOC cable is usually suitable for short distance transmission, the maximum transmission distance is generally within 100 meters. Fiber optics, on the other hand, can achieve long-distance transmission, the transmission distance can be up to several kilometers or even farther. In terms of transmission speed, AOC cables generally support up to 100Gbps or more, while fiber optic transmission speed is higher, can reach Tbps level.

3. Installation and Maintenance Costs: AOC cables are less expensive to install and maintain than fiber optics; AOC cables do not require additional fiber optic connectors and equipment, and can simply be plugged into an adapter or device port. While the installation and maintenance of fiber optic requires specialized tools and techniques, which are more costly.

4. Anti-interference ability: As the AOC cable integrates an electronic chip, it has high anti-interference ability and can maintain stable transmission quality in complex electromagnetic environments. Fiber optics, on the other hand, is not affected by electromagnetic interference and has better transmission quality stability.

According to the above differences, we can choose the appropriate network transmission medium according to the actual needs. If the demand is short distance transmission and lower cost requirements, you can choose AOC cable. For long distance transmission and higher transmission speed requirements, optical fiber is a better choice.


What is an Active Optical Cable?

AOC is an optical cable embedding optical fibers and microelectronics within a cable jacket. The line uses lasers and photodiodes to convert electrical signals into optical signals, which are transmitted through the fiber cables.

Strengths and Weaknesses of Active Optical Cable

1. AOC supports longer transmission distances than DAC, up to 100 meters for 40Gbps or 10Gbps.

2. AOC is less susceptible to electromagnetic interference (EMI) than DAC, increasing reliability in noisy environments.

3. AOC can be more expensive than DAC, especially for shorter transmission distances.

What is a Direct Attach Copper Cable?

DAC is a copper cable with an SFP+ or QSFP+ connector. The cable technology eliminates the need for a separate transceiver and delivers electrical signals directly from one device to another.

Strengths and Weaknesses of Direct Attach Copper Cable

1. DAC is typically less expensive than AOC for shorter transmission distances.

2. DAC is more durable than AOC, making it more suitable for cable management applications.

3. DAC is more susceptible to EMI, decreasing performance and reliability in noisy environments.

What are the differences between Active Optical Cable and Direct Attach Copper Cable?

The most significant difference between AOC and DAC is their transmission medium. AOC uses optical fibers, and DAC uses copper wires. AOC is generally used for longer transmission distances, whereas DAC is suitable for shorter distances.

When should you use Active Optical Cables?

AOC is preferred when high performance, long transmission distances, and low EMI susceptibility are vital factors. It is commonly used in data centers and computing applications, such as high-performance computing (HPC) clusters, switches, and storage interconnects.

When should you use Direct Attach Copper Cables?

DAC is an excellent choice for short-distance transmission, where the cost is a primary consideration. It is widely used in data center applications where copper cables are ideal for connecting devices nearby. Some typical applications include switch-to-server connections and rack-to-rack connections.

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