DAC & ACC & AEC & AOC

1. DAC (Direct Attached Cable)

Definition: DAC is a passive (无源) cable directly connecting two devices, such as network switches, servers, or storage systems.

Features:

1. No active components (such as amplifiers or chips) are present.

2. Signals are transmitted purely via copper wires.

3. Lower cost compared to active cables since it requires no additional electronics.

4. Ideal for short-distance connections (typically less than 7 meters).

Use Case: It is common in data centers to connect devices within the same rack or in adjacent racks.

2. ACC (Active Copper Cable)

Definition: ACC is an active (有源) copper cable, which includes electronic components to enhance or boost signal quality.

Features:

1. Contains an embedded amplifier or equalization chip to extend the effective transmission distance and improve signal integrity.

2. Generally more expensive than passive DAC cables.

3. Suitable for slightly longer distances than DAC cables, typically up to 15 meters.

Use Case: Used in environments requiring more reliable signal transmission than DAC cables can provide.

3. AEC (Active Electric Cable)

Definition: A specific type of ACC that uses a DSP Retimer chip to enhance performance.

AEC is an active copper cable but relies on digital signal processing (DSP) for better signal integrity and longer transmission distances.

Features:

1. Uses a Retimer chip (explained below), which processes the digital signal, reduces jitter, and re-transmits it cleanly.

2. Superior to standard ACC cables in performance but generally more expensive.

Use Case: High-speed applications that demand clean and accurate data transmission over copper wires.

4. Redriver Chip

Definition: A Redriver chip is an analog signal amplifier. It strengthens the signal by boosting its power to maintain integrity over distance.

Features:

1. Linear input and output: The signal is amplified but not re-processed digitally.

2. No digital signal regeneration, which means it can introduce some noise if the original signal is degraded.

3. Lower cost compared to Retimer chips.

Use Case: Used in less demanding scenarios where slight signal degradation is tolerable.

5. Retimer Chip

Definition: A Retimer chip is a digital signal processor (DSP) that re-generates the signal. It corrects errors and outputs a clean signal.

Features:

1. Processes the signal digitally, reducing jitter and noise.

2. Provides superior signal quality compared to Redriver chips.

3. Enables much longer transmission distances.

4. More expensive than Redriver chips due to the advanced DSP technology.

Use Case: Critical in high-speed data transmission (e.g., 25G, 40G, 100G Ethernet), where signal integrity is paramount.

6. AOC (Active Optical Cable)

Definition: AOC is an active cable that uses optical fiber instead of copper. It converts electrical signals to optical signals for transmission, then back to electrical signals at the destination.

Features:

1. Lightweight and immune to electromagnetic interference (EMI).

2. Capable of much longer transmission distances than copper cables (up to hundreds of meters or even kilometers).

3. More expensive than copper-based cables.

Use Case: Used in data centers, high-performance computing (HPC), and applications requiring long-distance, high-speed connectivity.

7. IEEE 802.3

Definition: This is the core Ethernet protocol defined by the Institute of Electrical and Electronics Engineers (IEEE). It governs wired Ethernet networks, including both copper and optical transmission.

Key Features:

1. Defines standards for Ethernet speeds such as 10 Mbps, 100 Mbps, 1 Gbps, 10 Gbps, 40 Gbps, 100 Gbps, and beyond.

2. Covers physical layer (PHY) and data link layer specifications.

Use Case: Forms the backbone of all modern Ethernet networking technologies.