What is the essence of SDN?

The essence of Software-Defined Networking (SDN) lies in its ability to create a centralized control point that orchestrates the entire network. By constructing a centralized control brain, SDN enables network administrators to have a unified view and control over the entire network, which facilitates the optimal management of global traffic. This centralized approach allows for more dynamic, flexible, and efficient traffic management compared to traditional networking, where control and data planes are closely integrated.

In essence, this centralized intelligence can make real-time decisions about traffic flow based on current conditions, policies, and requirements. It enables quick adaptation to changing network conditions, enhances the ability to implement complex policies across the entire network, and allows for greater automation and orchestration of services.

Other aspects such as localized traffic control, decentralizing network functionalities, and limiting network access are aspects that fall within the broader framework of networking but do not capture the primary goal of SDN. The focus of SDN is fundamentally about centralizing control to optimize and manage network resources efficiently.