Data Center Cabling: SFP+ DAC Cables vs AOC Cables

The digital age we live in thrives on data, and data centers are the beating heart of this world. At the core of these data centers are the complex cabling systems, mainly involving Direct Attach Copper (DAC) cables VS Active Optical Cables (AOC). DAC VS AOC cables are the preferred cabling options for high-speed data center applications. They both perform the function of connecting switches to routers and servers, but they have significant differences in terms of construction, cost, power consumption, and distance limitations.

DAC vs AOC Basics and Types

Direct Attach Copper Cables (DAC)

Direct Attach Cables (DAC) are bifurcated into two categories: Passive DAC and Active DAC. The classification is based on their signal transmission functionality.

A Passive DAC cable, as the name suggests, lacks any form of signal conditioning or amplification. The distance of the passive dac is less than 7 meters. This means it transmits data without any adjustments or enhancements to the signal, hence termed “passive”. Owing to this lack of electronic components, passive DAC cables tend to be less expensive, making them an economical choice for data transfer applications within short distances.

Conversely, an Active DAC cable incorporates electronic components to enhance and amplify the signal during transmission. The distance of the passive dac is less than 15 meters. The transmitted signal is continuously compared with the original data, allowing the cable’s electronic circuitry to detect and correct any discrepancies or distortions in real time. This ensures a high-quality data transmission, especially beneficial for long-distance applications or scenarios where high-resolution audio is required.

Active Optical Cables (AOC)

On the other hand, AOC cables use fiber optic technology to transmit data over longer distances (up to 100 meters). They come with transceivers already attached, which convert electrical signals into optical signals and vice versa, making them a plug-and-play solution. While they offer a better performance over longer distances, they are more expensive and consume more power.

Comparison: DAC vs AOC

In the quest for efficient data center cabling, several factors need to be considered. Beyond distance, power consumption, and cost, factors such as cable weight, cable size, and bend radius also play a significant role in decision-making. Here’s a more detailed comparison between DAC and AOC cables:

DAC Cable(Active and passive)AOC Cable
Maximum Distance≦15m≦100m
Cable TypesTwinax copper cableMultimode OM3/OM4 Fiber Cable
Power Consumption≦0.5W≦1W
Cable WeightHeavierLighter
Cable Size4.2mm(30AWG)6.0mm(24AWG)Typical 3.0mm
Bend Radius24 AWG=38mm

Small Form-Factor Pluggable Plus (SFP+) DAC and AOC cables are typically used for 10G Ethernet networks. SFP+ DAC cables can reach up to 10 meters, making them suitable for close-range connections. They offer low power consumption, low latency, and are more cost-effective than their AOC counterparts.

AOC cables, on the other hand, provide an efficient solution for longer distances up to 100 meters or more. While they consume more power, AOC cables provide better signal quality over longer distances. They are also thinner and lighter, offering better airflow and easier cable management in dense networking environments.

AOC vs DAC Application Scenarios

Depending on the specific requirements of your data center, you might choose between DAC and AOC cables.

DAC cables are ideally suited for short-distance, high-speed interconnections between servers and switches within the same rack or adjacent racks. They provide a cost-effective solution for high-speed data transfers with low latency.

AOC cables are the preferred choice for longer inter-rack cabling, usually connecting devices across different racks or rows. They are immune to electromagnetic interference, providing more reliable performance for critical networking tasks. They are also favored in areas where weight and radius of cable bend could be an issue due to their light and flexible nature.

Choosing Between DAC and AOC

The choice between DAC and AOC depends on the specific requirements of your data center or networking environment. Here are some key considerations to help guide your decision-making:

DAC Cables:

DAC cables are a popular choice for high-performance computer systems, large-scale commercial operations, and storage applications due to their superior short-distance transmission capabilities. These cables consume very little power, making them highly energy-efficient and cost-effective. They offer low latency, ensuring fast and seamless data transmission, which is crucial in a high-performance computing environment.

DAC cables shine in scenarios where the connected devices, such as rack-mounted network servers and storage, are located in close proximity to top-of-rack switches. Given their maximum transmission distance of 10 meters, they are ideally suited for intra-rack connections or between adjacent racks. So, if your primary need is short-range, cost-effective, and power-efficient cabling with high performance, DAC cables would be the perfect fit.

AOC Cables:

Active optic cables, in contrast, are your go-to solution for long-distance transmission. These cables can transmit data up to 100 meters or more, making them suitable for interconnecting devices located across different racks or even rows. They offer ultra-high bandwidth, which ensures that high volumes of data can be transmitted simultaneously without any performance drop.

The physical attributes of AOC cables also make them an appealing choice. They are small, light, and flexible, which makes them easy to install and manage, especially in dense networking environments. In addition, AOC cables are immune to electrical interference, which ensures a more stable and reliable performance, particularly in environments with a high degree of electrical noise.


DAC vs AOC cables largely depends on the specific needs and architecture of your data center. Therefore, when choosing the appropriate cabling solution, consider factors such as distance, power consumption, cost, and the specific application scenario in your data center. By doing so, you can ensure you’re leveraging the right technology for the optimal operation of your data center.


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