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Tutorial/AOC VS DAC: which is your better option for IDC Optical Network

AOC VS DAC: which is your better option for IDC Optical Network

There is no doubt that the volume in the data center has been increasing along with the rapid development of Ethernet, posing a real challenge to the regular low transmission rate for data center services. Therefore, an upgrade on low data rate is inevitable in order to meet the communications tougher requirement for network bandwidth. In addition, the traffic between servers in the data center will dominate the future data traffic. The interconnection solution between short and medium distance is an important issue that every optical component manufacturer cannot ignore.

Currently, there are three main interconnections in data centers in terms of short and medium distance, i.e. interconnection between servers and switches, storage and switches, and interconnection between switches. For optical devices, there are two connection methods: DAC cable connection and AOC cable connection. Here the question is in what situation you should use DAC or AOC cable? What are the pros and cons of these two types of network cables? The following part of this article will make a brief comparison between Direct Attach Cable and Active Optical  Cable and finally provides advice on the application of the two cable solutions.

10G, 25G, 40G, 100G, 400G DAC AOC Cable for servers, TOR switches and core swithces in data centers

◮ DAC & AOC Cable Solution for IDC High-Speed Interconnect 

1. What DO DAC and AOC Cables have in common?

Both DAC and AOC are common cabling solutions for data networking and are usually used for high-speed, high-reliability interconnection and transmission required by data centers, high-performance computers, and large-capacity storage devices.

Both of their ends have cable assemblies of a module, which are connected to fixed ports only. Besides, DAC and AOC cables can be manufactured in different lengths to support different transmission data rates, such as 10G SFP DAC/AOC cable, 25G AOC cable, 40G AOC cable, 100G DAC cable.


2. What are the differences between DAC and AOC cables?

 Features of DAC

There are two types of high-speed DAC(Direct Attach Cable); one is Active Copper Cable(ACC), the other is Passive Copper Cable(PCC). The difference between the two Ethernet cables is that the former is designed with a built-in driver chip. DAC is composed of a silver-plated copper conductor and foamed insulated core wire and it is widely applied in the concentrated interconnection within 5m/10m. The "module" on the DAC  cable is not a real optical module since it has no components and can only transmit electrical signals. Therefore, high-speed cables are cheaper than other ordinary optical devices.

AOC VS DAC: which is your better option for IDC Optical Network

Fiber Mall QSFP-40G Passive DAC Cable 3m

● Features of AOC

AOC is composed of two optical transceivers and an optical cable jumper. The transceivers at both ends of the active optical cable are for photoelectric conversion. Compared with DAC cable, AOC (Active Optical Cables) has better anti-electromagnetic interference (EMI)performance and other advantages such as high transmission rate, supporting longer transmission distance, low latency, and less energy consumption. For medium and short-distance within the range of 300m, the data center users can freely customize the cable length according to the actual situation, while the DAC is only limited to the application within a 10m transmission distance.

QSFP28 100G AOC(Active Optical Cable)

Fibe Mall QSFP28 100G AOC Cable

3. When do you use DAC Cables?

According to the Frabic architecture announced by Facebook, a server and Top-of-Rack switches(ToR) constitute the basic unit of the data center. Generally speaking, the distance between a ToR and a server NIC(Network Interface Card) is less than 5 meters. In this situation, DAC is more advantageous than AOC cables in the respects of cost, power consumption, and heat dispersion. Thus, DAC is a preferred option to IDC interconnect systems. Besides, on some special occasions, 100G QSFP28 to 4*SFP28 DAC is an alternative direct connection according to the users specific demand for the data connection.

QSFP28-4*QSFP28 100G Passive DAC cable

◮ Fiber Mall QSFP28-4*QSFP28 100G Passive DAC 

 4. When do you use AOC Cables?

Nevertheless, the transmission distance between ToRs and edge core switches is usually less than 100m, where Integrated circuits are deployed densely. Therefore, the active optical cable is a better cabling solution for data connection due to its merits of lightweight, small wire diameter, and manageable cabling maintenance. Since the data center has strict specifications on signal transmission, AOC is better than twin-ax DAC cable in signal integrity and optical coupling design, greatly reducing the errors in signal processing. Furthermore, the high-frequency EMI signal is processed within pluggable optical modules, AOC optical cable has a better EMI performance than DAC network cable. Undoubtedly, AOC is your first option in the interconnection between switches and switches within short or intermediate reach.



It can be concluded that either active optical cables(AOC) or direct attach copper cables(DAC) are the better cabling solution for IDC networking according to different application demands. When there are few transmission requirements for the data center, the DAC solution is suggested as a better internet cable solution for the interconnection between the server and the switch within 5m/10m, while the AOC cable solution is perfect for the interconnection between switches and the switches. By all means, it is unnecessary to analyze which is the better solution, that is AOC cable is always your first for performance is way much more important than cost if budget is never your concern.