The question is an interesting one: Is software-defined WAN now just the WAN? In other words, has the idea of software-defined become the norm to the point where we don't need to specify it anymore in relation to the WAN?
The answer: Not yet, but the day is coming. As SD-WAN chips away at the market, it's quietly redefining what network teams want from their WAN.
Keep in mind: SD-WAN has already pretty much supplanted most legacy WAN optimization, which is now routinely an add-on to an SD-WAN service rather than a standalone purchase. WANs that had optimizers are now mostly SD-WANs.
So, what about the rest of the WANs? The writing is on the wall.
SD-WAN features become baseline expectation
Even for businesses with modest IT needs, it's increasingly difficult to get much done without network connectivity. As a result, tolerance for outages is decreasing.
For businesses setting up new locations, redundant and active-active WAN connectivity using whatever media is available -- coax, copper, fiber or wireless -- from whichever provider with automatic failover is becoming the baseline expectation. This also happens to be the baseline functionality of SD-WAN.
At the same time, WAN staff are getting harder to find as seasoned professionals retire and are not replaced by new workers. SD-WAN's emphasis on automation makes it a natural option for helping network teams adjust to network changes, expectations and innovation.
Note also, network as a service (NaaS) offerings mostly provide key SD-WAN functionality. The increasing number of organizations that now opt for NaaS have, in effect, shifted to SD-WAN. And, increasingly, traditional managed WANs are also managed SD-WANs. The MSPs see they can get more profit from networks that are easier to manage and more resilient.
Is SD-WAN the future?
Lastly, SD-WAN is coming for traditional WANs under the guise of cybersecurity initiatives. Whether it is firewall as SD-WAN node or SD-WAN as the anchor of Secure Access Service Edge, cybersecurity-led deployments are replacing legacy WANs with SD-WANs across industries and in organizations of all sizes.
So, although SD-WAN has not yet completely replaced legacy WANs -- and will not for many years to come given the slow rate of change in some organizations -- it is well on its way to doing so. Importantly, though, SD-WAN has changed what enterprises of all sorts expect from their WAN. Inevitably, eventually, any WAN will deliver at least the core of what is now considered SD-WAN functionality.