After the network in the traditional IT architecture is deployed according to the business requirements, if the business requirements change, it is very cumbersome to modify the configuration of the corresponding network devices (routers, switches, firewalls). In the rapidly changing business environment of Internet/mobile Internet, the high stability and high performance of the network are not enough to meet the business needs, but flexibility and agility are more critical.
What SDN does is to separate the control right on the network equipment and manage it by a centralized controller, without relying on the underlying network equipment (routers, switches, firewalls), thus shielding the differences with the underlying network equipment. The control right is completely open, and users can customize any network routing and transmission rules and policies they want to achieve, thus being more flexible and intelligent.
After the transformation of SDN, there is no need to repeatedly configure the router of each node in the network, and the devices in the network are automatically connected. You only need to define simple network rules when using it. If you don't like the built-in protocol of the router, you can modify it by programming to achieve better data exchange performance.
If there are several services in the network, such as SIP, FTP and streaming media, and the total network bandwidth is certain, then if the streaming media service needs more bandwidth and traffic at a certain moment, it is difficult to handle in the traditional network, but it is easy to realize in the network after SDN transformation. SDN can temporarily thicken the "pipeline" of streaming media, increase the bandwidth of streaming media, and even close the "pipeline" of SIP and FTP when the demand for streaming media decreases.
It is precisely because of the openness of this business logic that the development space of the network as a "pipeline" becomes infinite. If the business application mode of cloud computing in the future can be simplified as "cloud-tube-end", then SDN is an important technical support for the link of "tube".