What Is Direct Attach Cable (DAC)?

In today’s data center, more bandwidth is needed to support the Internet users. To accommodate the ever-growing number of operating systems and applications, the improvement of data transmission between the serves and switches is in the urgency. Direct Attach Cable (DAC) is the exact this kind of cable to solute this long-troubled problem. As an emerging product, it has a bright prospect beyond it. But what’s is it? What’s the function of it? Some basic information about DAC will be provided in this passage, such the definition, function and types.

Introduction to Direct Attach Cable (DAC)

Direct Attach Cable (DAC) assembly is a high performance integrated duplex data link for two-directional communication over optical or copper cable for lengths up to 50 m. It provides 4 pairs of data channels at transmission speeds up to 120 Gbit/s. Source of cable and speed are two different ways to categorize DAC. The two main sources of DAC are copper and optical cable. The source of copper is divided into active cable for longer transmission distance and passive cable for shorter distance. On the basis of speed, the DAC can be divided into 10G, 25G, 40G and 100G. This text is mainly described according to different sources of DAC.

Copper DAC

The copper DAC is generally divided into active cable and passive cable. Because there is a silicon semiconductor (a silicon chip) in active cable, it has longer transmission distance than passive cables. Passive cabling provides a direct electrical connection between corresponding cable ends and it is liable to degrade the light they carry, and that would cause attenuation, insertion loss power loss due to channel impairment. The copper DAC supports higher data rate than traditional copper interfaces-from 4Gbps to 10Gbps per channel. It’s interchangeable and hot swappable with fiber optic modules. The copper DAC is a cost effective solution over optical transceivers and cables for short reach applications. The advantages of copper DAC are lower costs, higher reliability and no interrupts while the disadvantages of it are limited management interface.

Active Optical Cable

Active Optical Cable (AOC) is a cable that mates with standard electrical interfaces, which is designed for a higher data bandwidth to replace copper technology in data transmission. Active optical cables are fiber cables for data transmission that use a semiconductor (a silicon chip) to boost the performance of the cable. In active cables, one or several semiconductor chips are embedded in the cable to fix up impairments. Because of this type has optics or electronics embedded within the connectors, Active Optical Cable can improve signal quality and provide a longer cable distance. And the active feature allows cables to be more thinner, longer, compact and transmit data faster than passive ones. Compared with copper DAC, AOC provides more advantages, such as enhanced signal integrity, longer cable lengths, active/adaptive receive equalization, management interface, low power consumption, lower connection loss and etc. But the cost of Active Optical Cable is relatively higher than copper DAC. Nowadays, Active Optical Cables are used to connect consumer devices such as cameras, HDTVs and enterprise networks which back up the modern data communication systems.

Conclusion

Direct Attach Cable (DAC) is a high performance data link for two-directional communication over optical or copper cable for lengths up to 50m at a speed of 120 Gbit/s. It is most commonly categorized as two kinds, copper DAC and Active Optical Cable (AOC). If you are in a tight budget, you can choose copper DAC for data link to meet your requirement. Given that you ask for a high quality and longer distance, the active optical cable is a good choice. You can order any one of it to make your need meet.