In the first post of this series we took a look at the problems that current generation WANs don’t have great answers for.  In the second post of the series we looked at how SD-WAN is looking to solve some of the problems and add efficiencies to your WAN.


If you haven’t had a chance to do so already, I would recommend starting with the linked posts above before moving on to the content below.


In this third and final post of the series we are going to take a look at what pitfalls an SD-WAN implementation might introduce and what are some items you should be considering if you’re looking to implement SD-WAN in your networks.


Proprietary Technology


We've grown accustom to having the ability to deploy openly developed protocols in our networks and SD-WAN takes a step backwards when it comes to openness.  Every vendor currently in the market has a significant level of lock in when it comes to their technology.  There is no interoperability between SD-WAN vendors and nothing on the horizon that looks like this fact will change.  If you commit to Company X's solution, you will need to implement the Company X product in every one of your offices if you want it to have SD-WAN level features available.  Essentially we are trading one type of lock in (service-provider run MPLS networks or private links) for another (SD-WAN overlay provider). You will need to make a decision about which lock-in is more limiting to your business and your budget.  Which lock-in is more difficult to replace, the MPLS underlay or the proprietary overlay?


Cost Savings


The cost savings argument is predicated on the idea that you will be willing to drop your expensive SLA backed circuits and replace them with generic Internet bandwidth.  What happens if you are unwilling to drop the SLA? Well the product isn't likely to come out as a cost savings at all.  There is no doubt that you will have access to features that you don't have now, but your organization will need to evaluate whether those features are worth the cost and lock-in that implementing SD-WAN incurs.


Vendor Survivability


We are approaching (might be over at this point) 20 vendors which are claiming to provide SD-WAN solutions. There is no question that it is one of the hottest networking trends at the moment and many vendors are looking to monopolize.  Where will they be in a year?  5 years? Will this fancy new solution that you implemented be bought out by a competitor, only to be discarded a year or two down the line?  How do you pick winners and losers in a highly contested market like the SD-WAN market currently is?  I can't guarantee an answer here, but there are some clear leaders in the space and a handful of companies that haven't fully committed to the vision.  If you are going to move forward with an SD-WAN deployment, you will need to factor in the organizational viability of the options you are considering.  Unfortunately, not every technical decision gets to be made on the merit of the technical solution alone.


Scare Factor


SD-WAN is a brave new world with a lot of concepts that network engineering tradition tells us to be cautious of.  Full automation and traffic re-rerouting has not been something that has been seamlessly implemented in previous iterations.  Controller based networks are a brand new concept on the wired side of the network. It's prudent for network engineers to take a hard look at the claims and verify the questionable ones before going all in.  SD-WAN vendors by and large seem willing to provide proof of concept and technical labs to convince you of their claims.  Take advantage of these programs and put the tech through its paces before committing on an SD-WAN strategy.


It's New


Ultimately, it's a new approach and nobody likes to play the role of guinea pig.  The feature set is constantly evolving and improving.  What you rely on today as a technical solution may not be available in future iterations of the product.  The tools you have to solve a problem a couple of months from now, may be wildly different than the tools you currently use.  These deployments also aren't as well tested as our traditional routing protocols.  There is a lot about SD-WAN that is new and needs to be proven.  Your tolerance for the risks of running new technology has to be taken into account when considering an SD-WAN deployment.


Final Thoughts


It’s undeniable that there are problems in our current generation of networks that traditional routing protocols haven’t effectively solved for us.  The shift from a localized perspective on decision making to a controller based network design is significant enough to be able to solve some of these long standing and nagging issues.  While the market is new, and a bit unpredictable, there is little doubt that controller based networking is the direction things are moving both in the data center and the WAN.  Also, if you look closely enough, you’ll find that these technologies don’t differ wildly from the controller based wireless networks many organizations have been running for years.  Because of this I think it makes a lot of sense to pay close attention to what is happening in the SD-WAN space and consider what positive or negative impacts an implementation could bring to your organization.