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What is the difference between QSFP DAC and AOC?
Knowledge Base + 2024.01.10

QSFP (Quad Small Form-Factor Pluggable) DAC (Direct Attach Cable) and AOC (Active Optical Cable) are two types of high-speed interconnect solutions used in data center and networking environments. Both are designed to connect switches, routers, and other networking equipment over short distances, but they use different technologies for signal transmission. Here are the key differences between QSFP DAC and AOC: 

  1. Technology:

    • QSFP AOC uses fiber optic cables with integrated optoelectronic transceivers at each end. Unlike DAC, these transceivers use active components to convert electrical signals to optical signals and vice versa.

    • AOCs can support longer distances compared to DACs due to the use of optical components.

    • QSFP DAC uses copper cables with integrated transceivers at each end. These transceivers convert electrical signals to optical signals at the cable ends.

    • It is a passive copper cable with no active components between the connectors.

    • QSFP DAC (Direct Attach Cable):

    • QSFP AOC (Active Optical Cable):

  2. Distance:

    • Can support longer distances than DACs, often ranging from a few meters to tens of meters.

    • Generally suitable for short-distance connections within the data center, typically up to a few meters.

    • QSFP DAC:

    • QSFP AOC:

  3. Power Consumption:

    • Higher power consumption due to the active optical components.

    • Lower power consumption compared to AOC since it doesn't have active components.

    • QSFP DAC:

    • QSFP AOC:

  4. Flexibility:

    • More flexible and less prone to bending restrictions due to the fiber optic cable construction.

    • Typically less flexible and more prone to bending restrictions due to the copper cable construction.

    • QSFP DAC:

    • QSFP AOC:

  5. Cost:

    • Higher cost due to the active optical components and the use of fiber optics.

    • Generally less expensive compared to AOC.

    • QSFP DAC:

    • QSFP AOC:

  6. Use Cases:

    • Suitable for connections that require longer distances within a data center, such as connections between racks or in environments where flexibility is essential.

    • Commonly used for short-reach connections within racks or adjacent racks in data centers.

    • QSFP DAC:

    • QSFP AOC:

Both QSFP DAC and AOC solutions have their advantages and are chosen based on specific requirements, including distance, power consumption, and cost considerations. The choice between the two depends on the specific needs of the networking infrastructure.