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200G AOC vs DAC Cables: An Overview and Practical Applications

Posted on Jan 18, 2024 by
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In this article, we will delve into the world of 200G AOC and DAC cables, exploring their definitions, differences, and diverse applications. By understanding their unique characteristics and optimal uses, we can harness their potential to enhance connectivity efficiently.

200G AOC vs DAC Cables: Overview

200G AOC: 200G AOC (Active Optical Cable) is a communication cable that utilizes external power to convert electrical signals to optical signals or vice versa. It employs optical transceivers at both ends for photoelectric conversion and transmission, achieving a blazing transmission rate of 200Gb/s. Comprising two transceivers and a fiber optic patch cable, the AOC offers significant transmission distances, typically up to 100 meters.

200G DAC: 200G DAC (Direct Attach Copper) cables provide a cost-effective alternative to AOC cables for short-range data transmission. These cables utilize copper conductors to transmit electrical signals, eliminating the need for optical components. FS 200G DAC Cable can be further subdivided into ACC (Active Copper Cable) and passive DAC. Since copper wires are lossy, they cannot be made too long to ensure reliable transmission of high-speed signals. However, an active signal driver or equalizer chip is added inside ACC. These active chips can compensate for part of the loss caused by copper transmission, so they can transmit 2 to 3 times farther than Passive DAC. (200G Passive DAC: up to 3 meters, 200G ACC: up to 7 meters).

200

200G AOC vs DAC Cables: Similarities & Differences

Similarities

Direct connection: Both 200G AOC and DAC cables provide a direct connection between active equipment ports such as switches, servers, and storage devices. The transmission modules are pre-terminated onto the cable (Twinax copper for DAC and fiber for AOC) and cannot be removed. This allows for easy plug-and-play installation without the need for additional cabling.

Coded to equipment: DAC/AOC cables require programming of the modules to match the specific equipment they are connected to. While some equipment manufacturers accept a generic MSA code, major vendors like Arista, Cisco, Dell, and Juniper require AOC and DAC cables to be coded with their proprietary codes. Accurate coding ensures compatibility of the connection.

Differences

Transmission medium: When comparing AOC vs DAC cables, it is crucial to understand that their primary distinction lies in the variance of transmission medium. Specifically, AOC cables are composed of fiber optic material, belonging to the realm of fiber-optic communication, whereas DAC cables are made of copper wire, falling within the domain of electrical communication.

Since AOC uses optical fiber transmission internally, it has a long transmission distance, easy to wire, and is not sensitive to electromagnetic radiation.; Due to the physical limitations of copper, the DAC transmission distance is extremely short and will be subject to electromagnetic interference. However, the AOC contains a laser, while the DAC does not contain optical devices inside, so they have low power consumption and low insertion Lossy. As the price of fiber optic material is more expensive than copper cable, the cost of the laser is also very high, so the price of the AOC is much higher than the DAC.

Form factors: Both 200G AOC and DAC cables are available in two main form factors: QSFP56 and QSFP-DD.

  • QSFP56 form factor: QSFP56 (Quad 50 Gigabits Small Form-factor Pluggable) is specifically designed for 200G Ethernet, evolving from the 40G QSFP+ and 100G QSFP28. It utilizes 4 x 50G channels and achieves higher network speeds compared to QSFP+ and QSFP28. The key change is the transition from NRZ encoding to PAM4 encoding.

  • QSFP-DD form factor: QSFP-DD (Quad Small Form Factor Pluggable Double-density) supports two data rate configurations. With NRZ modulation, it achieves data rates of up to 25G x 8 channels for 200G network transmission. With PAM4 modulation, the data rates can reach 50G x 4 channels, enabling 400G network transmission for high-performance computing data centers and cloud networks. QSFP-DD modules can support 400Gbps, while QSFP56 is limited to 200Gbps, making the QSFP56 form factor more commonly used for 200G optical transceivers and AOC/DAC cables.

 
Cable Type Transmission Medium Form Factor Modulation Format Cable Length Max. Power Consumption
200G AOC Fiber QSFP56 to QSFP56 PAM4 1-100m(3-328ft) 4.5W
QSFP-DD to QSFP-DD NRZ 1-70m(3-230ft) 4W
QSFP56 to 2x QSFP56 PAM4 1-30m(3-98ft) 4.5W
QSFP-DD to 2x QSFP28 NRZ 1-70m(3-230ft) 4W for 200G module, 2.5W for 100G module
QSFP56 to 4x SFP56 PAM4 1-70m(3-230ft) 5.5W for 200G module, 3W for each 25G module
QSFP-DD to 8x SFP28 NRZ 1-70m(3-230ft) 4W for 200G module, 1W for each 25G module
200G Passive DAC Copper QSFP56 to QSFP56 PAM4 0.5-3m (2ft-10ft) 0.1W
QSFP-DD to QSFP-DD NRZ 0.5-3m (2ft-10ft) 0.1W
QSFP56 to 2x QSFP56 PAM4 0.5-3m (2ft-10ft) 0.5W
QSFP-DD to 2x QSFP28 NRZ 0.5-3m (2ft-10ft) 0.5W
QSFP56 to 4x SFP56 PAM4 0.5-3m (2ft-10ft) 0.5W
QSFP-DD to 4x QSFP28 NRZ 0.5-3m (2ft-10ft) 0.5W
QSFP-DD to 8x SFP28 NRZ 0.5-3m (2ft-10ft) 0.5W
200G ACC Copper QSFP56 to QSFP56
PAM4
3-7m (10ft-23ft)
1.5W
QSFP56 to 2x QSFP56
PAM4
3-7m (10ft-23ft) 1.5W

200G AOC vs DAC Cables: Applications

Based on the aforementioned details, it becomes evident that the 200G DAC cable is well-suited for cost-effective, low-power short-distance applications, commonly deployed within the same or neighboring racks in data centers. On the other hand, the 200G AOC cable offers extensive transmission distances, typically ranging from 1 meter to 70 meters. However, it comes at a higher cost and consumes more power. Therefore, the AOC cable is suitable for scenarios that require convenient wiring or long transmission distances, often deployed in high-density environments such as data centers and HPC (High-Performance Computing) setups.

Both 200G DAC AOCs can be used in 200G to 200G, 200G to 2x100G, 200G to 4x50G, and 200G to 8x25G network data migration.

200G to 200G DAC vs 200G to 200G AOC

200G to 200G DAC vs 200G to 200G AOC

200G to 2x100G DAC vs 200G to 2x100G AOC

200G to 2x100G DAC vs 200G to 2x100G AOC

200G to 4x50G DAC vs 200G to 4x50G AOC

200G to 4x50G

200G to 8x25G DAC vs 200G to 8x25G AOC

200G to 8

Conclusion

From the comparison between 200G AOC vs DAC Cables in capabilities, transceiver form factors, and applications, we can effectively leverage the nuances to select suitable products. Whether it's for data centers, high-performance computing, telecommunications, or cloud computing, FS offers versatile connectivity solutions tailored to specific needs.

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