As IT organizations become increasingly aware of the benefits of a software-defined wide area networking (SD-WAN), the rate of adoption is growing rapidly. International Data Corp. (IDC) forecasts that the SD-WAN market will be valued at $6 billion by 2020.

Brad Casemore, an industry analyst with IDC, attributes much of that growth to the need to find the most efficient way to connect remote office to cloud applications. Instead of backhauling all that traffic through a local data center, SD-WANs provide a platform capable of directing network traffic either directly over a standard Internet connection to a cloud application, while routing other traffic over, for example, an MPLS line to securely access an enterprise application running in a local data center.

Of course, many SD-WAN advocates champion the technology as a way to save money, especially when compared to a basic T1 line. Depending on the scenario, deploying an SD-WAN appliance can significantly reduce MPLS bandwidth expenses by as much as 24 percent or more, according to SD-WAN experts.

In fact, some classes of applications once used MPLS networks because there simply wasn’t a viable alternative available when they were first deployed. Thanks to improvements in Internet performance and the ability to enforce security policies on SD-WANs, some of those legacy applications are migrating away from legacy WAN technologies in much the same way that many applications move off mainframes.

No one expects SD-WANs to completely supplant MPLS networks any time soon, but Casemore said MPLS networks are clearly under siege. Most organizations will continue to rely on MPLS to provide low-latency access to, for example, enterprise resource planning (ERP) applications.

David Molony, an industry analyst with Ovum, said that while SD-WANs are being included in almost every request for proposal (RFP), most SD-WANs are being deployed as an optimization tool that gets laid down over an existing router-based network.

There is certainly enough interest in SD-WAN to foster competition between a host of start-up vendors that are competing against incumbent providers of networking equipment trying to protect their router and WAN optimization appliance bases.

Longer term, Yousuf Khan, CIO for Pure Storage, a provider of storage systems for the enterprise, said most of the usage of SD-WANs is aimed at specific applications such as backup and recovery. Khan said in time he expects more architectural approaches to deploy SD-WANs to emerge. And those new approaches will play a part in how data is managed across what is becoming an increasing distributed computing environment in the age of the cloud.

Not only do users in remote offices need to be able to transfer data into application residing in multiple data centers, the metadata those applications create are increasingly being funneled into data lakes based on repositories such as Hadoop. The need to analyze all that data winds up creating even more bi-directional flows of data over what will eventually become a common SD-WAN fabric.

As SD-WANs take hold in the enterprise, the requirements for these solutions is driving many organizations toward embracing what is alternatively known as “thin branch” or “thin edge” computing. SD-WANs effectively enable IT organizations to combine routing, WAN optimization, and stateful firewalls into a single platform. While there is a lot SD-WAN versus MPLS debate, SD-WANs provide both MPLS connectivity and direct Internet access and management across both. Multiple links improve overall resiliency when any link fails. Voice calls can continue even if MPLS transport goes down.

Other capabilities required in today’s SD-WANs include intelligent application or flow-based load-sharing and line conditioning to improve the quality and reliability of the multiple connectivity options. More advanced capabilities include many of those found in WAN optimization products such as forward error correction to deal with lossy Internet connections and efficient packet re-ordering to handle packets in the same connection that arrive out of order because they were sent on different links.

Beyond managing links, SD-WANs also have to embrace the handling of cloud applications (SaaS). Historically, with MPLS, most traffic is router back to corporate HQ and then traverses the corporate network and firewalls to reach the outside world. SD-WAN solutions can and should recognize popular cloud applications and allow those to be accessed directly without routing traffic back to home base. This can improve overall performance.

Of course, managing networks at that level of scale is also going to push many IT organizations to reevaluate their own internal capabilities, which is one reason managed SD-WAN services are becoming more prevalent. Regardless of how organizations decide to optimize the edge of their networks, however, the one thing that is clear is there’s going to be a lot less network appliance clutter in the branch office.