Another potential growth opportunity for SD-WAN is in the Universal Customer Premises Equipment (uCPE) model of delivering SD-WAN as a VNF on a white box. This approach provides end-users with room to grow -- adding other VNFs such as WAN optimization or security, for example, on a single white box.
However, this model can be expensive for enterprises and the benefits of NFV -- such as the ability to swap licensing from one vendor to another and add or remove functions without dispatching field engineers -- are are a lower priority in the near term for enterprises and require a heavy commitment, says Washburn.
"A lot of enterprises would turn around and say, 'well, I don't have plans to change my infrastructure in the next three years. It's a theoretical benefit but I don't need to swap out my router every three months,'" he explains. "Moving to the cloud and virtualizing has typically meant lower costs, at least up front, but NFV isn't less expensive and in some cases is more expensive. It just hasn't been a high-priority issue for a lot of enterprises."
Enterprises are interested and know the transition to NFV is important in the long run, but they're moving forward slowly, "implementing here and there like in the data center, but they're not ready to go big and replace existing routers," adds Washburn.
The economic issue is one major concern for enterprises, adds Perrin, but there are also issues with openness and standardization since multiple vendor's VNFs reside on one box.
"You're buying a box that does multiple things but if you haven't deployed those multiple things on day one and you're not quite sure what you're going to do, it's cheaper to buy the single-function box," says Perrin. "It's tough for a vendor or service provider to go to their customer and argue to pay more today for potential tomorrow."
While hurdles remain for the success of the uCPE model for delivering SD-WAN, it is a more compelling deployment model for telecom operators offering SD-WAN as a managed service, explains Perrin. This model makes it simpler for telcos and cable companies to deliver new managed services to customers.
Washburn echoes Perrin's assessment: The "great majority of SD-WAN today, even when it's software, is run on bare metal. So they're taking an x-86 box and routing the application up, it's taking direct control of processes in the box and behaves like a piece of hardware. Most customers are ordering SD-WAN in that traditional way."
Enterprises are still grappling with the best approach to SD-WAN, and there's still a learning curve, says Washburn. Maybe an enterprise picks an SD-WAN platform, but it ultimately doesn't meet their requirements, or they've started on a proof of concept with a service provider but "don't know what step two looks like" and aren't sure how to move forward.
"The challenge with SD-WAN comes down to enterprises trying to figure out how to approach the SD-WAN environment … some vendors say 'it's zero-touch provisioning, this practically manages itself, the centralized controller makes it easy to administer,' and don't fully reflect that SD-WAN has a different set of challenges and it's still quite a complicated technology."
- SD-WAN Update: 5G Impact Still to Come, as the Market Consolidates
- MEF Debuts Final Draft SD-WAN Service Standard
— Kelsey Kusterer Ziser, Senior Editor, Light Reading