In the Beginning, There Were Boxes

End users started deploying software-defined wide area networking (SD-WAN) as a way to create their own virtual privates networks and to save money on access costs. Enterprise users always want the simplest possible solution, so each SD-WAN supplier provided a turnkey offering. Everything was pre-integrated, so it was simple to acquire and deploy.

Implementing SD-WAN in hardware appliances made a lot of sense. It gave end users what they wanted, and made it easy to use. But these users started to see the drawbacks of an appliance-based approach.

What if they needed a feature their supplier couldn’t support? Rip and replace.

What if their supplier was not providing adequate support? Send out expensive IT staff to each and every site. Perceptive IT leaders started to ask themselves: “In the age of cloud and software, why are we deploying hardware appliances?”

Service Providers to the Rescue?

Deploying hardware appliances is an issue, but the problems with SD-WAN don’t stop there. User-managed SD-WAN deployments put CIOs in the role of being their own network provider and integrator. Consider the case of a CIO at a multinational corporation using SD-WAN with numerous local access providers. Who do you call when there are WAN issues? Look in the mirror.

End users want the benefits of SD-WAN: lower cost, application visibility and service agility. They don’t want to run their own networks, so they went back to the telcos. “Give us managed SD-WAN.” Service providers had previously viewed SD-WAN as a threat to their Layer 3 VPN offerings and revenue. But when customers demand a service, you don’t have much choice but to respond. Time was of the essence, so what did service providers do? You guessed it. They rolled out SD-WAN services based on closed and vendor-specific hardware appliances at the customer site.

Customers got what they wanted (a managed offering), but they were back to square one in terms of feature and service agility. Any big change to feature or function would require changing physical infrastructure at every site.

There has to be a better way for end users and for service providers.

SD-WAN Should Fit Into a Cloud-Centric Architecture

With so much buzz in the SD-WAN community about features and cost, we sometimes forget that the “S” in SD-WAN stands for software. Software virtual network functions (VNFs) are now available for SD-WAN, so why use closed hardware appliances to deliver an innovative service?

Service providers know that deploying appliances to deliver SD-WAN is problematic. We have already seen that using closed hardware appliances creates risk regarding features and supplier responsiveness. The risks don’t stop there.

An additional drawback is that using appliances ties a service to the infrastructure. Changing the service means changing the infrastructure. This approach is contrary to the service provider’s vision of being able to treat services like applications. In that cloud-centric model, services are defined, built, delivered, and managed at the speed of software. This eliminates the need to change underlying hardware and frees us from worrying about its details. Using a VNF version of SD-WAN is much more consistent with that cloud vision.

Integrate SD-WAN With Universal Platforms

Service providers have solved the immediate customer demand by using hardware appliances. They are now moving to software VNFs running on open commercial off the shelf (COTS) servers. This change is in conjunction with an overall move to universal CPE (uCPE). With uCPE, service providers can deploy all of their virtualized services on a common, low-cost COTS platform. This approach enables the dynamic deployment of a wide variety of software VNFs available on-demand. In addition, service providers can scale down the server for residential and small business applications. They can also scale up the server for large businesses and multiuser applications. The big benefit is that they can use the same software on all of these platforms, creating a consistent service offering. They also get a consistent management interface – integrate once, deploy many. None of these advantages are available with hardware appliances.

Use Software for SD-WAN

Service providers are eager to gain the benefits of cloud-centric innovation while reducing cost and power. Part of this innovation is giving end users the services they want, such as SD-WAN. Service providers should move forward with a cloud-centric architecture that hosts software functions on open COTS platforms. This approach enables the use of technologies like software-defined networking (SDN) and network functions virtualization (NFV) to create and deploy lucrative new services. Likewise, end users should demand that new services be deployed as software running on open servers.

Any other approach is a step backward to the bad old days of vendor lock-in – for end users and for service providers.