What is Software Defined Networking and why is it heating up?

Over the past couple of months a few start-up SDN companies have been purchased by major vendors, e.g. VMware picking up Nicra. Do you need to take note and what’s going on?

Firstly YES, you need to be on-top of this as it will affect your future! The issue here is that traditional networking is causing a number of issues as it is too restrictive, to take us into the future of the “hybrid cloud”. So in summary, in the future you will still have your physical topology as well as essentially a logical one, the logical one is basically where SDN comes into play.

To simplify the problem right down the IP system was designed to connect two devices together. Two issues with this as we move to the cloud are:

–       In its design, it starts by finding a path between the two devices, and then connects them together. Now when one of the devices suddenly moves, the system breaks down!

–       The interface today describes the devices identity, (my MAC address is me!), however today we are more interested in the service being provided. Similar to the change in virtualising servers, we used to think about a physical box being our server, (“There is our Exchange server!”), now we think about the application,(“Which VMware cluster is your Exchange running on?”), not related to a specific box.

So there is a need to separate out the control of the network traffic and retain the physical networking to move the data in-order to move into a dynamic and service oriented world.

There are a couple of major initiatives underway in this space, such as the ‘Open Network Foundation (ONF) founded last year by a consortium of vendors and end users to promote the use of SDN. Their major piece of work is to create an open interface standard which is called ‘Openflow.’ As expected, enterprise networking giant Cisco is also working in this area and they have an API/SDK kit called the ‘Open Network Environment Platform Kit, (OnePK), to foster an ecosystem around their switching and routing devices.

To try bring this all together, imagine you are a cloud provider. You need to deliver to your customers a network which looks just like what they have on their site and you need to deliver the service level that you are contracted to them to deliver, however you have to provision this from your highly leveraged infrastructure. How do you do that? You put a ‘virtual network layer’ on top of your physical one, let’s call that a software defined network!


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