• Should my next networking switch support SDN?

Software-defined networking (SDN) is around a decade old now, but most companies still haven't jumped on it. Let's look at what it is and why you might want to consider it for your own business.

To understand SDN, let's look at how traditional networks operate. A switch or router receives a packet, and decides where to send it next. That might be to another switch or router, which might forward it on again until the packet eventually reaches its destination. IP-based networks (that is, any network compatible with the modern internet) have worked that way for years.

The problem with this model is that switches and routers only know the next stage of a packet's journey, which they store in a table. If a device two or three steps along the chain has a problem, like a hardware failure or some traffic congestion, they won't be able to look ahead and change where they send the packet so that they can route around it.

Another problem is that if you want to reconfigure end-to-end routing on a network, perhaps to add a new router or switch, or to optimise the network for a new application, you have to manually log into every router or switch and reconfigure the routing table. That's time-consuming and error-prone.

SDN solves this problem by taking over the routing decisions on the switch or router's behalf. An SDN controller manages routing across all compatible switches and routers. This is called the control plane. The switches and routers still forward the data according to the SDN controller's instructions. They now make up the data plane.

Why use SDN?

SDN makes more sense the larger and more complex your network is, or the more frequently it changes. It lets you add new routers and switches to the network more easily, managing manage routing changes, bandwidth allocation, and service testing.

It's also useful as an automated problem-solving mechanism. Now that switching and routing control is defined in software you can customise traffic routing according to business conditions. Creating rules in the controller helps automatically route around network congestion, and you can even configure application-aware traffic.

This level of control makes it easy to prioritise traffic. If you add a video conferencing service to your network or have a data scientist that needs to move large amounts of traffic to their big data application, you can reshape the network to suit. SDN also gives you a central view of your resources so that you can see what's happening in the network and tweak it manually if you need to. And programmable networking means that you can configure security throughout your network on the fly.

Should I put it in my switch?

Should you get an SDN-enabled switch or router? It makes more sense to think about all your devices in an SDN context, because all your packet-forwarding equipment should support SDN if the concept is going to work properly.

Take a look at your existing equipment to see if it's already compatible. The most popular protocol for sending instructions from the controller to the data plane is called OpenFlow, and if it supports this, it will already plug neatly into a compatible network. You'll still need to buy the controller, though, or it won't work at all.

SDN is a great option for businesses that expect their networks to do more than just shunt files around. If you're planning on making technology a platform to develop new applications and services that will drive your business, or if you're using private or hybrid cloud models, it's well worth a look.

Check out the popular switches below