One of the most common complaints about SDN that comes from entry-level networking folks is that SDN is going to take their job away. People fear what SDN represents because it has the ability to replace their everyday tasks and put them out of a job. While this is nowhere close to reality, it’s a common enough argument that I hear it very often during Q&A sessions. How is it that SDN has the ability to ruin so many jobs? And how is it that we just now have found a way to do this?
Measure Twice
One of the biggest reasons that the automation portion of SDN has become so effective in today’s IT environment is that we can finally measure what it is that networks are supposed to be doing and how best to configure them. Think about the work that was done in the past to configure and troubleshoot networks. It’s often a very difficult task that involves a lot of intuition and guesswork. If you tried to explain to someone the best way to do things, you’d likely find yourself at a loss for words.
However, we’ve had boring, predictable standards for many years. Instead of cobbling together half-built networks and integrating them in the most obscene ways possible, we’ve instead worked toward planning and architecting things properly so they are built correctly from the ground up. No more guess work. No more last minute decisions that come back to haunt us years down the road. Those kinds of things are the basic building blocks for automation.
When something is built along the lines of predictable rules with proper adherence to standards, it’s something that can be understood by a non-human. Going all the way back to Basic Computing 101, the inputs of a system determine the outputs. More simply, Garbage In, Garbage Out. If your network configuration looks like a messy pile of barely operational commands it will only really work when a human can understand what’s going on. Machines don’t guess. They do exactly what they are told to do. Which means that they tend to break when the decisions aren’t clear.
Cut Once
When a system, script, or program can read inputs and make procedural decisions on those inputs, you can make some very powerful things happen. Provided, that is, that your chosen language is powerful enough to do those things. I’m reminded of a problem I worked on fifteen years ago during my internship at IBM. I needed to change the MTU size for a network adapter in the Windows 2000 registry. My programming language of choice wasn’t powerful enough for me to say something like, “Read these values into an array and change the last 2 or 3 to the following MTU”. So instead, I built a nested if statement that was about 15 levels deep to ensure I caught every possible permutation of the adapter binding order. It was messy. It was ugly. And it worked. But there was no way it would scale.
The most important thing to realize about SDN and automation is that we’ve moved past simply understanding basic values. We’ve finally graduated to a place where programs can make complex decisions based on a number of inputs. We’ve graduated from simple if-then-else constructs and up to a point where programs can take a number of inputs and make decisions based on them. Sure, in many cases the inputs are simple little things like tags or labels. But what we’re gaining is the ability to process more and more of those labels. We can create provisioning scripts that ensure that prod never talks to dev. We can automate turn-up of a new switch with multiple VLANs on different ports through the use of labels and object classes. We can even extrapolate this to a policy-based network language that we can use to build a task once and execute it over and over again on different hardware because we’re doing higher level processing instead of being hamstrung by specific device syntax.
Automation is going to cost some people their jobs. That’s a given. Just like every other manufacturing position, the menial tasks of assembling simple pieces or performing repetitive tasks can easily be accomplished by a machine or software construct. But writing those programs and working on those machines is a new kind of job in and of itself. A humorous anecdote from the auto industry says that the introduction of robots onto assembly lines caused many workers to complain and threaten to walk off the job. However, one worker picked up the manual for the robot and realized that he could easily start working on the it instead of the assembly line.
Tom’s Take
Automation isn’t a magic bullet to fix all your problems. It only works if things are ordered and structured in such a way that you can predictably repeat tasks over and over. And it’s not going to stop with one script or process. You need to continue to build, change, and extend your environment. Which means that your job of programming switches should now be looked at in light of building the programs that program switches. Does it mean that you need to forget the basics of networking? No, but it does mean that they way in which you think about them will change.
The Networking Nerd 