In the world of IT, hot topics usually come and go quite quickly.  However, SD-WAN remains a topic of interest among any client with multiple locations. While many networking technologies are often labeled “the next big thing,” SD-WAN is delivering on the promise. Adoption rates are increasing exponentially and production implementations are happening almost daily. Companies that are refreshing WAN edge equipment, renegotiating carrier contracts, building out new branches, or aggressively moving apps to the cloud, should be seriously considering SD-WAN. When advising clients on this, MNJ usually gets the question, “are there any downsides?”

With this backdrop in mind, here are some of the downsides that we have seen in SD-WAN deployments:

• Substantial security gaps at branch locations could occur if the internal security posture does not align with the deployment of SD-WAN as whole.  While there may be an overall savings in the cost of your WAN by introducing SD-WAN, customers should review the security strategies to ensure their deployment is not compromised with a security breach. Many well-known vendors/products will not discuss this with you because it simply is not their business, but it should be brought up with your IT team or vendor.
• SD-WAN can facilitate a move towards lower-cost Internet transport, but this can lead to challenges in managing heterogeneous connectivity.  MPLS did something that everyone knows about, but that most people don’t really appreciate – consolidate office interconnectivity over a single vendor.  The proverbial “single-hand to shake.”  In speaking with clients who were early adopters of SD-WAN, I discovered that nearly all started bringing in multiple low cost bandwidth connections, only to find that the offerings prompted them to bring in a third-party aggregator to manage it.  Managing the various vendors became a full-time job, which was not anticipated when deploying.
• Despite fancy marketing terms like “software defined” and “touchless provisioning,” it still involves hardware and a time investment from your IT group.
• SD-WAN offers a fancy GUI interface for administration, and while this makes for ease of management, it also abandons knowledge of the traditional skills associated with networking.  While this is great when everything is functioning flawlessly, it can tend to cause issues in design as well as supporting problems with the implementation.   
• SD-WAN is much easier to configure and operate than traditional routers, yet many SD-WAN implementations have added technical debt to the branch because clients can’t relinquish the comfort a traditional router brings them.  Most vendors allow for clients to keep their routers, but that doesn’t mean customers should.  As SD-WAN adoption rates continue to increase, routers will become more and more obsolete.