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Building blocks of SDN network

Hey all, you must be quite comfortable with SDN, after creating a good connection with SDN. Now it is time to get into personal details of SDN 😛 . By that I mean, let us see what are the Building blocks of SDN network.

If you remember the story in my earlier articles, Google Maps (controller), Tom N Jerry (switches) were the lead characters. So, it is quite obvious that controller, switches/routers, along with the applications form the three main building blocks of SDN. The SDN environment which you have pictured, should be somewhat like below:


Open Networking Foundation (ONF) has documented the above SDN architecture. ONF is the organisation which aims to promote and adopt SDN using open source standards.

Now, Applications are the programs that interact with the controller, to specify their networking needs. They use the information returned by the controller to make policy driven decisions. Applications communicate with the controller using the Northbound interfaces, as shown above. It is this application layer that makes network programmable and flexible.

SDN Controller is the brain of SDN networks. It acts as an intermediate layer between applications and network devices. It accepts the needs of applications, transfers them to network components and communicates the network information back to the application layer. It also provides an abstracted view of the entire network to the upper layer.

Network Devices carry out the forwarding and processing of the data. These devices interact with the controller by using Southbound interfaces. OpenFlow is the major Southbound standard, which helps network elements interact with the controller, we shall go into more details about it later.

As we know, SDN is all about separating the control and data planes. Network devices form the data plane whereas SDN Controller forms the control plane. The control plane is logically centralized, also is decoupled from the data plane, as you can see above.

I gave an overview of a simple architecture, if you wish to have a better perspective of various SDN principles and it architectural implementations, you can refer this document formulated by ONF for further research activities. You can find good SDN resources at SDxCentral as well.

You must be feeling a strong connection with SDN. Well, guys, there is still lot more to know about SDN, so stay connected.

Happy networking with SDN..!!

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