SDN:Software Defined Network

Concept:

SDN architectures decouple network control and forwarding functions, enabling network control to become directly programmable and the underlying infrastructure to be abstracted from applications and network services.

How Does SDN Work?

SDN providers offer a wide selection of competing architectures. At its most simple, the software-defined networking method centralizes control of the network by separating the control logic to off-device computer resources. All software-defined network solutions have some version of an SDN controller, as well as southbound and northbound application program interfaces (APIs):

Controllers:

The “brains” of the network, SDN Controllers offer a centralized view of the overall network, enabling network administrators to dictate to the underlying systems (like switches and routers) how the forwarding plane should handle network traffic, and offering a holistic view of network behavior and loads.

Southbound APIs:

SDN uses southbound APIs to relay information to the switches and routers “below.” OpenFlow, considered the first standard in SDN, was the original southbound API, and once was considered synonymous with SDN. While popular, it is no longer the only API available on the market, as other companies have released their own proprietary versions of it.

Northbound APIs:

SDN uses northbound APIs to communicate with the applications and business logic “above.” These help network administrators to shape traffic and deploy services through program instead of by manual configuration.

Advantages:

After the network in the traditional it architecture is deployed online according to the business requirements, if the business requirements change, it is very tedious to modify the configuration on 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 requirements, but flexibility and agility are more critical. SDN does is to separate the control rights on the network devices, be managed by a centralized controller, without relying on the underlying network devices (routers, switches, firewalls), and shield the differences from the underlying network devices. Control is completely open, and users can customize any network routing and transmission rule policy that they want to implement, thus making it more flexible and intelligent.