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The Fuss on Software Defined Networking (SDN)

Today, we shall go ahead and establish whether SDN is really worth the fuss it has generated over the last few years. We shall identify its pros as well as its cons and conclude whether it is really a giant leap for mankind, or just a small step that shall be eliminated in the near future. Let’s dive right in and demystify this concept that has caused a tiny little bit of confusion, shall we?

To understand a small section of networking, you need to understand networking in general. For starters, we going to need to define a network. A network (the computer network) is a set of computing devices connected together for the purposes of sharing data and resources – this is the simplified definition. Now, I know there are several kinds of computer networks depending on how devices are organised, coverage area and so forth but that is quite not the scope of this article. This article covers the management of a network through the use of programs rather than hardware devices. Well, you still need the hardware devices for the network – but that is not the point here. Read on to understand the core of this technology.

Software Defined Networking is a networking architecture that enables the control of a network to become directly programmable and obstructs the underlying architecture from applications and networking services. This architecture separates the network control and packet forwarding functions enabling dynamism, cost-efficiency, adaptability and manageability.

Wait, but network administrators do this all the time and manage the network through a graphical interface on their computers. Isn’t that already software defined? Yes, you could conclude that with a but. For traditional network configurations, these tools that an administrator uses are mostly device level management tools that are different from one manufacturer to another. There is also a main factors that dominates traditional networks; Network functionality is implemented in a dedicated appliance and the functionality within this appliance is implemented in dedicated hardware.
 This tells you that hardware is the core in configuration and control. This includes switches and routers for appliances and Application Specific Integrated Circuits (ASIC) for dedicated hardware within the appliance.

Traditional networking configuration has numerous advantages and has been used over so many years (more than two decades) but still, it is time consuming and error prone. For you to be an efficient network administrator, you need to be knowledgeable with multiple devices from various vendors and how they work. In addition, for network upgrades, a lot of hardware configurations have to be taken into account and there is likelihood of error in the process. Finally, we can say that traditional network architecture complicate network segmentation.

That is where SDN comes to the rescue.

We already defined what SDN is earlier; now it is time to understand it further and get its pros – and cons. It is worthy to note that there are still no universally accepted standards on some concepts of this networking paradigm. Some basics are useful to contemplate upon though. One of the most prominent concepts you come across when dealing with SDN is decoupling software and hardware. Two things are synonymous with this concepts; the control plane and the data plane. The former deals with the logistics of where to send traffic while the latter deals with the logical decisions and forwarding of traffic. In this regard, the control plane is executed using software while the data plane is executed using hardware. With this kind of arrangement, abstraction is ensured and therefore policies need not be executed from the hardware itself rather, a centralised software application is used for network virtualisation.

So, what are the benefits of SDN? The first advantage comes in with flexibility. The administrator is able to configure the network more accurately, consistently and with fewer errors. Secondly, it easier to optimise the flow of data through the network.

With the concept understood, we are going to revisit this topic in a more detailed article later.

Now, you know.

Gichuki P. Mwangi

A computer scientist with a passion to solve real world, day to day problems using new computer technologies and those already in existence.

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