With the rapid development of the network, high density is the trend of network networking, and the port density and bandwidth are increased through switch integration. The question is, should we buy switches with more ports or should we achieve port density and bandwidth by buying switches with cascading capabilities? The answer is obvious, the latter tends to be more powerful.

Switch stacking is to combine multiple switch devices that support stacking features, and then use dedicated cables and modules to plug in ports with stacking functions, connect these switches together, and combine them logically into a switching device. By controlling the configuration of the main switch, the purpose of configuring the entire stack unit switch is achieved. Only one IP address can be used to manage multiple stack switches, which can improve network efficiency and simplify management. The main switch is responsible for the operation, management and maintenance of the system.


Other member switches can serve as the backup of the master switch and process services at the same time. Once the main switch equipment fails, the system will quickly and automatically select a new main switch to ensure uninterrupted business. Through switch stacking, it can realize high network reliability, large amount of network data forwarding, and simplify network management.

Switch stacking can be deployed in a limited space, not only providing higher density ports, but also saving space costs, and powerful management functions prove to be the most cost-effective alternative to the underlying high-end switches. However, stacking is only applicable to switches that can be stacked in the same series from the same supplier, and the link distance is limited by the length of the stacking cable.

Currently, there are three main switch stacking modes:

1. DAC high-speed cables are directly stacked.

2. AOC active optical cables are directly stacked.

3. Optical module + optical fiber jumper stacking.

Since DAC, AOC, and optical modules can all realize the stacking of switches, when to choose DAC high-speed cables/AOC active optical cables? When to choose optical module stacking?

First of all, DAC high-speed cables are cable assemblies with fixed lengths and modules at both ends. Modular connectors cannot be separated from copper cables. The modules at both ends of the DAC high-speed cable do not have expensive optical lasers and electronic components, and can only transmit electrical signals, not optical signals. Compared with AOC and optical modules, the price of DAC is much lower. This is a low-cost short-distance connection solution that saves cost and power consumption in short-distance applications.

However, the transmission medium used by DACs is copper, which is susceptible to electromagnetic interference. Therefore, optical fibers are often used for long-distance signal transmission. Optical fiber is far superior to copper cable media in terms of insulation and isolation characteristics, and the transmission distance is longer. Generally speaking, in general applications, DAC high-speed cables are used to stack switches below 7 meters (usually switches in the rack), which can greatly reduce the cost. AOC active optical cable or optical module + fiber jumper will be used to extend the distance between devices over 7 meters.

Secondly, the AOC active optical cable is composed of a fixed-length optical cable at both ends and two modules, and the module and the optical cable cannot be separated. The modules at both ends of the AOC can provide photoelectric conversion with light transmission function. Theoretically, the AOC active optical cable has the same transmission effect as the combination of 2 optical modules + 1 fiber jumper, and the cost of AOC with the same transmission distance is slightly lower than 2 optical modules + 1 fiber jumper, but because the length of the AOC cable is fixed , the two modules are connected together, if a module fails, the entire AOC needs to be replaced at the same time, if one module fails, only one module needs to be replaced.

Therefore, AOC active optical cables are generally used for short-distance transmission in data centers. Generally speaking, AOC can be used within a distance of 30 meters, which can achieve the purpose of saving costs.

To sum up, DAC high-speed cables are practical and economical, and are often used for data transmission or switch stacking below 7 meters. AOC active optical cable is used for switch data transmission or stacking between 7-30 meters, and optical module + fiber jumper is used for more than 30 meters.