SD-WAN could be viewed as a trend that will fade, but the technology's ability to leverage Internet resources has lasting potential.
Only a year ago, software-defined wide area networking (SD-WAN) was still emerging as an application of SDN principles directed at the enterprise WAN. Since then, the SD-WAN bandwagon has grown to include not only new entrants and the incumbent networking vendors but related solutions such as WAN optimization and WAN path control, and even wireless.
So is SD-WAN over-hyped? Yes, it's likely approaching that status, but that is driven by real-world deployments and benefits. These can be called "over the top," both literally and figuratively. In a literal sense, SD-WAN enables the deployment of an overlay logical network on top of the physical transport. The advantage of separating the control plane from the data plane applies not only to SD-WAN solutions themselves but in effect to the diverse underlying physical transport.
Figuratively, SD-WAN is enjoying well-deserved interest from enterprises large and small. Continuing increases in bandwidth requirements are difficult to meet solely with expensive private WANs. So, enterprises have been facing either a painful budget or bandwidth issue -- one that SD-WAN can help solve with the addition of Internet broadband to WAN networks. Early adopters have achieved cost savings of 75% or more versus other approaches.
While hybrid networks with Internet mostly as backup have been deployed before, the policy-based simplicity of SD-WAN makes it practical to leverage diverse circuits from different providers across a large-scale deployment. The use of SD-WAN along with broadband services has also enabled IT to deliver rapid deployments that businesses are demanding.
SD-WAN can also address performance requirements that have previously depended on provider SLAs. Advanced solutions can "engineer in" performance even on top of Internet transport delivered as a best-effort service. This is achieved by continuously monitoring circuit performance and both dynamically steering traffic and correcting degradations such as packet loss and jitter. That allows network-sensitive applications like voice, video conferencing, virtual desktops and custom interactive apps to leverage all available bandwidth.
Changes in WAN architecture are inevitable because of the underlying shift of compute and applications to the cloud. The Internet provides not only the cost and flexibility benefits, but is the logical path to the cloud. Requiring enterprises to build private networks to cloud hosted services severely affects the benefits of migrating applications to the cloud in the first place. The challenge has been to build a path to the cloud as robust, secure and manageable as a private network, and SD-WAN technology that extends its managed overlay to cloud destinations can address this.
Service providers are adopting SD-WAN to help customers migrate to the cloud and lessen the DIY element. Cloud service providers including UCaaS providers have embedded virtualized and multi-tenanted SD-WAN capabilities to enable performance, security and manageability of their cloud services. MSPs are leveraging SD-WAN to enhance their ability to manage their clients' WANs. And service providers are using SD-WAN to offer hybrid network services and provide access into private backbones.
Emerging requirements for the Internet of Things hint at further uses for SD-WAN. The massively scalable network required to connect IoT devices to cloud control and analytics over any available circuit could be an opportunity for SD-WAN overlay. The potential is truly "over the top."