SDN architecture understanding

Question

I am very new to SDN and want to know just a basic understanding of it so that I can explain to some simple what it is. From what I know that the architecture is broken into the three layers. The infrastructure layer is just the switches and routers, and other devices that makes up a network. The controller layer maps how the devices are connected and how forwarding of packets should be sent from one device to another. For the controller layer to actually do the work in mapping and knowing how to forward the packets, the application layer provides the logic to do so and this is the layer where you create your network application in certain programming language like Python. Did I get a basic understanding of how SDN layers work?

Answer 1

We need to understand few terms before going to SDN.

Control Plane: The plane that determines where to send traffic

Data Plane: The plane that executes these decisions and forwards traffic

Management Plane: Element of a system that configures, monitors, and provides management, monitoring and configuration services to, all layers of the network stack and other parts of the system

Traditional Network Devices:

• Control Plane, Management Plane and Data Plane reside on device itself.
• Each device has its own brain and disconnected from each other and uses all sorts of protocols to stay connected.
• Yet such protocols are complex and levels of resiliency to control action of such protocols also complex.
• Think of traditional network as the type of network that is more prone to failure due to multiple disconnected brains not working together with one another.

SDN: (Decoupling hardware from Software)

SDN architecture is divided into 3 layers

1. Application Layer
2. Control Layer
3. Infrastructure Layer

Infrastructure Layer:

Consist of Network Devices which contains Data Plane and work on Open Flow Protocol or you can say uses Open Flow API to communicate.

Control Layer:

Consist of Control Plane and Management Plane.

Application Layer:

In this layer user can get an overview of Devices and see Topology.

Link between Application and Control Layer is generally called NorthBound Interface

Link between Control Layer and Infrastructure is called SouthBound Interface

Benefit of SDN:

• Decoupling Control and Data planes involves leaving the data plane with network hardware and moving the control plane into a software layer.
• By abstracting the network from the hardware, policies no longer have to be executed on the hardware itself.
• Instead, the use of a centralized software application functioning as the control plane makes network virtualization possible.

Answer 2

You may find useful this: SDN Layer Architecture