Author: Car chubby
link: https: //www.zhihu.com/question/264188247/answer/281626808
The deepest reason for stacking a lot of use: in order to exclude competitors! Whether it is Cisco, Huawei, or other manufacturers, there are no exceptions. Please refer to the following for details. The first use of stacking was in 2008. A corporate network of about 500 people, Cisco 29xx, the company is located on the same floor, there is only one computer room, 4 stacked into a logical switch (logical whole), a total of 3 such logical switches were created , Used 12 switches. If it is not for the system's restrictions on the number of stack members, the length of stacking cables, and the space restrictions on the number of switches in a rack, 12 switches can be stacked into one switch.
The main benefits of stacking are:
1) Small management burden Managing one switch is naturally less burdensome than managing multiple switches, and it can also avoid configuring port channels between member switches.
2) Save the number of interconnection ports of the switch. For data transmission between member switches, stacking cables are used. Stacking cables can be regarded as an external extension of the internal data bus of the switch, thus saving the need for interconnecting ports.
3) The external appearance is a switch, which can use the conventional LACP protocol to negotiate the Port Channel with the server, instead of using private protocols such as VPC or MLAG, allowing the server to negotiate the Port Channel with the ports across the switch.
4) Because it is a private realization, it is exclusive and can better exclude competitors.
Limitations of Stacking As mentioned above, data synchronization and user traffic transmission between stack member switches usually use stacking cables, which are extensions of the internal data bus. Therefore, how data is synchronized and how traffic is transmitted is completely It is the self-realization of the manufacturer, which is like how the traffic inside a switch is transmitted, and what format transmission is privately realized. Once there is a problem, the user will see the strange trace log alarm output, and will be confused. I remember that the idea of a new switch from the J family is that one computer room (data center) has one switch. Although there may be hundreds of member switches, only one switch will play the role of configuration management, and the other switches are only used as expansion boards. The role of, the switch uses interface functions for configuration, and data synchronization and user traffic transmission use private implementations. This is actually a kind of SDN (Sao De Network).