What is SDN?
SDN (Software Defined Networking) is a network approach that separates the control plane, which determines how data is transmitted through a network, from the data plane, which physically transports the data. This separation allows for centrally managing the control plane and distributing the data plane, resulting in a more flexible and programmable network.
In traditional network models, the control and data planes are integrated into network devices such as routers and switches. This means that the control plane is responsible for both determining the route that data should take through the network and physically transmitting it. This can be inflexible and difficult to manage, especially in large networks.
SDN seeks to solve this problem by decoupling the control plane from the data plane. The control plane is centralized and runs on an independent controller, which can be a physical or virtual machine. The controller is responsible for making decisions on how data should be transmitted through the network and sends instructions to the data plane, which is implemented on network devices such as switches and routers.
A key advantage of SDN is that it allows for easier programming of the control plane. Network administrators can use software to define and implement policies and rules on how data should be transmitted through the network. This can be done in real-time, allowing for quick and flexible responses to changing network conditions.
Another advantage of SDN is that it allows for greater visibility and control over the network. With a centralized control plane, network administrators can easily monitor and manage the network from a single location. This can facilitate troubleshooting and optimize network performance.
SDN also allows for the use of network virtualization. Network administrators can use software to create virtual network devices, such as virtual switches and routers, that can be easily created, deleted, or modified as needed. This allows for greater flexibility in terms of network configuration and can reduce the need for physical hardware.
There are several different approaches to implementing SDN, including OpenFlow, which is an industry standard for defining communication between the control plane and data plane. Other approaches include using APIs (application programming interfaces) to enable software to communicate with network devices and the use of network overlays, which allow for creating virtual networks over physical infrastructure.