What is SDN and How does it Work?

There have been many advancements in the field of Computer Networking. Today all we need is to cope with the vast variety of data formats and high speed of communication at the same time. SDN or Software Defined Network was conceptualized and designed to overcome previously existing problems with other networking systems like the Distributed system and Client/Server Based networks. This is surely a much-needed upgrade in networking technology.

SDN allows the networks to react dynamically to changes in the parameters like network patterns and resources. SDN provides a controller with which many applications are able to communicate in real-time. Due to the availability of a controller, networks can interact with applications with ease. This allows the applications to implement multiple logical network topologies on a single network type. Due to its ability to change and adjust the network architecture as per request the speed increases. The services thus provided are speedier and the effective cost of managing the network is also reduced considerably.

Open flow is an Open Networking Foundation (ONF) that is used to implement SDN. Its basic and foremost function is to instruct the network switch about the handling of incoming data packets. Open Flow is also used to define the interface between the open flow controller and switch. It is important to take note here that Open Flow is completely different from SDN networking. The working of SDN is detailed below:

How does SDN work?

SDN provides a wide range of architectures, but the basic task of each one is to command the control of the network by separating control logic from devices, computing resources, and other peripherals. SDN uses these components for its working:

A controller is like the backbone of the Software Defined Network. It offers a centralized view of all the devices making up the network. Another function of the controller is to provide support to a network administrator which helps in setting up the system to handle the communication and transmission traffic.

SDN uses Southbound APIs to pass information to switches and routers ‘below’, as the word suggests. Southbound APIs are one of the most commonly used protocols.

SDN uses Northbound APIs to communicate with the applications and the logic ‘above’. This is helpful in shaping the traffic and distributing several services.

A basic typical block diagram for an SDN Framework is shown below: