Now, I guess most of you reading this, already have an idea in your head of what SDN is, but without doubt, the most common question I am getting these days as a Cisco Canada Data Center Specialist is related to SDN. Some want to know what it is, some want to know what Cisco is doing about it, and some want to know how this will affect their business. Here’s a brief look at SDN from my perspective and what it means to your network.
What is SDN?
This is the most common question, but at the same time the hardest to answer. We use an old cartoon analogy in Cisco to talk about it, where various blind-folded people are all touching an elephant at different places. Each person’s perspective is completely different, some think it is a tree, some a fan, some a rope, some a hose, etc. Everyone in this cartoon is wrong, it is in fact an elephant.
I encounter many different perceptions of what a Software Defined Network is, but this time, in most cases, everyone is actually correct. Now, if you are an academic, you may not agree, there are some very rigid definitions of true SDN’s. However, in the business world, those definitions are less distinct. So what are some of these solutions?
“Standards Based” SDNs
In research and academic environments, “true SDN” is a suite a publically defined protocols that decouples control and data (or management and forwarding) components in the network, and uses open and standardised Application Programming Interfaces, to allow the control plane to send instructions to the data plane. Using this decoupling of data and control planes, it now becomes possible to direct traffic from one place to another, or with a variety of different policies and functions, based on instructions from higher automation tools, or even applications. This then provides the ability to manage traffic far more granularly than by using the topology defined by the networking protocols alone. SDN is primarily being developed under the moniker of OpenFlow by the Open Networking Foundation.
“Overlay” SDNs
Now, I don’t want to distract from, or confuse the fact that SDN really is the Open SDN described above, however, the term “SDN” is also now beginning to be used to define any case where a higher layer control environment is sending instructions or circumventing the classic control and data planes in the network. One example of this are the many “Overlay” networks that are now commonly referred to as SDN’s. In this case, protocols such as VXLAN and NVGRE are using variations on tunnelling protocols to send data between various points on the network, but creating ways of circumventing the actual topology that the network would historically have used to forward data. Overlay networks can be used for a number of reasons, the most common is to allow virtual machines to be moved from one location to another, and keep its IP addressing and identity unchanged. This can be from subnet to subnet within a Data Center, or potentially between Data Centers anywhere in the world.
“Proprietary” SDNs
In addition to the SDNs mentioned above, the rate of development in this industry also leads to the creation of a variety of proprietary implementations and capabilities that compete with or augment those being developed in the standards based communities. Vendor’s and innovators may offer specific value added capabilities, beyond those being offered in true SDN forums, which enhance customer’s productivity and offers features that would otherwise be prevented in those forums. Use of proprietary APIs could be used to give specific access directly to features built into the hardware, or allow interaction with the vendor’s protocols and capabilities. However, it is of course important to note that these proprietary solutions are often restricted to one or a limited number of vendors, so there becomes a trade-off of capability to openness which customers must choose between.
How will this affect your network?
Probably the most important of these questions is how will it affect your network? Unfortunately, there is no one clear answer to this, as there is no one clear solution that fits every customer’s needs.
Of course, that is the good part too, because SDN is bifurcating at a significant rate we are seeing a growing array of solutions that will provide significant value to our customers.
What is clear, is that SDN may offer significant value to you as a business of almost any size. The goal will be to identify your business needs you face and align the right solution to the problem.
What is Cisco doing about SDN?
Unsurprisingly, the answer to this question is clear and concise … “LOTS !!!”. Cisco has taken our customers desire to be able to programmatically control the network to heart, and has been working for the last two years on introducing SDN capabilities across our most of our product portfolio. For a complete list of our products and solutions, click here.
In a future post, I’ll be discussing how SDN is focused on delivering capabilities to the application. In the meantime, join the conversation @CiscoCanada or leave a comment in the section below.
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