Apis TechTip – What is SDN?

Welcome to this episode of Apis TechTips, a video series where we provide insights into the world of telecom with the help of excerpts from our training courses. 

This episode gives a basic understanding of what software-defined networking can look like, and comes from the course Cloud, NFV and SDN in an Hour.

We hope you enjoyed this TechTip! Do you want more insights about SDN? Discover Apis Training’s full course Cloud, NFV and SDN in an Hour.  

The course takes a deep dive into the following topics: 

  • An introduction to the Cloud 
  • The importance of virtualization  
  • Network Functions Virtualization (NFV)  
  • Software-Defined Networking (SDN) 
  • What OpenStack does and why you need it 

Learn more about Cloud, NFV and SDN here: https://apistraining.com/portfolio/cloud-nfv-and-sdn-in-an-hour/   

This TechTip is also part of a whole eBook of tips, all focusing on Cloud technology. We call it an eBook+ since all chapters are both text and video. If you want to read the text, you can do that, and if you want to watch a teacher tell the story, you can choose that.

All the video chapters are excerpts taken directly from our recorded lessons, so if one of them piques your interest, you can easily go to the course and dive deeper into that particular subject.

This particular eBook+ is called “Cloud Chronicles: A Journey into a Virtualized and Software-Defined World“, and you only need to CLICK HERE to request it for immediate download.

Below you can find the transcribed text for this particular TechTip.

What Is SDN?

What if we have a network that looks like the left side of the first image? It seems very weird. There’s a router, a switch, a diode of some kind, and other very strange-looking hardware-specific network pieces of equipment.

Couldn’t we do it like the right side instead? We buy these generic, white boxes, and we manage them centrally from the little brain in the middle. And it controls the generic boxes to behave in such a way that, from the outside, they look like the thought balloon. Which happens to be the exact same picture as the network on the left!

So from the outside, we can’t tell whether we’re connected to the left or right picture. But of course, there’s so much more flexibility on the right side because there, at the flip of a switch or the drop of a hat, I can just change how the network devices behave. On the left side, in order to change the functionality, I’d need to disconnect them and go away and buy another thing and connect it.
Sometimes the interface between the controller and the SDN devices (the red lines) uses a protocol called OpenFlow. I mention it because it’s a popular SDN protocol. It’s not at all the only way to do it, but it’s a popular protocol for controlling SDN devices.

One possibility with this is what’s called network slicing. Let’s say we have the little network seen in the second image, and maybe I’m sitting somewhere up there with the control computer, talking to the SDN controller, asking it to do something. Then customer A, compared to customer B may perceive the network completely differently.

Customer A sees a square of routers, while customer B sees a matrix of switches. Even though it’s the same physical network! This is sometimes called network slicing, but network slicing has a bigger meaning as well. This is network slicing specifically for transport networks, packet-forwarding networks. If you include network functions like higher-layer applications but still apply the same logic, then it’s all hardware infrastructure that is perceived differently depending on who is using it

Network slicing on both lower and higher layers is very popular in NFV and 3GPP, and 5G papers talk a lot about network slicing, for instance.

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