Spotlight On Software-Defined WAN

Most of the talk around software-defined networking focuses on the data center, but now the discussion is expanding to the WAN. Using expensive private MPLS links, WANs can be complex and costly. Applying SDN to the WAN is an emerging trend to tackle the problem.

At Interop New York this week, attendees had several opportunities to learn about the software-defined WAN. Greg Ferro, a network architect and engineer, led a workshop on the technology, calling it the "next wave of disruption in networking." His workshop looked at different approaches for transforming WANs from "expensive and blind to intelligent and flexible."

Peter Christy, networking research director at 451 Research, led a panel session on software-defined WANs that included representatives of three companies with different approaches to the concept. Christy kicked off his session by saying he doesn’t like the term software-defined. "The concept of virtualization really explains what's going on."

Virtualization of the WAN makes it easier to implement new LAN applications and make changes to the underlying physical infrastructure, he said. The value of virtualization of the WAN is in abstraction. While legacy WANs are difficult to manage and hard to utilize effectively, a virtual WAN can be more agile and easier to manage.

David Hughes, founder and CEO of Silver Peak, described how his company transitioned from WAN optimization to this new model. The increasing amount of traffic going over the Internet to cloud-based services is driving enterprises to rethink the old WAN model, he said.

This summer, Silver Peak launched its Unity WAN fabric, which is designed to bring together an enterprise network with public cloud services and monitor cloud traffic in order to route it over the least congested path.

Ramesh Prabagaran, vice president of product management at startup Viptela, said his company's technology uses edge devices that sit at branch locations and a centralized controller that provides enterprises with the ability to use multiple transport methods (broadband Internet, MPLS, LTE), plus visibility and segmentation for security.

Another startup, CloudGenix, also aims to reduce WAN complexity by building out a secure virtual network on top of the physical WAN and providing centralized control. Kumar Ramachandran, CloudGenix founder and CEO, said the design replaces the classic, brittle network model.

Cisco's take
In a keynote Thursday at Interop New York, Chris Spain, Cisco's vice president of the enterprise networking group, talked about the need to transform the WAN and showed how SDN can be applied to the WAN to make it more agile.

The old ways of building a WAN won't work anymore in the age of mobile devices and cloud applications, he said. "The rate of change is hitting our branch networks the hardest," Spain said. "And there's no more budget for you to buy new bandwidth."

Eighty percent of employees work in a branch office, yet the old model of backhauling traffic to the data center then to the Internet and back isn't sustainable, Spain said.

Cisco's "Intelligent WAN" (IWAN) takes an application-centric approach to WAN design, he said. Instead of building a WAN with private links only, IWAN shifts to a hybrid design that allows for the inclusion of cheaper direct Internet access and wireless 3G/4G connections in addition to MPLS links. This week, Cisco released a new series of ISR branch routers for this hybrid WAN design.

During his keynote, he and another Cisco representative demonstrated how the IWAN dashboard could work with Cisco's APIC Enterprise Module for campus and branch environments to provision policies for a new retail branch location. An enterprise could set policies for what applications are allowed, their priority, and what links they use.

"It's about translating the business logic into network logic," Spain said. "This allows us to manage at scale; configure [policy] one time and push it out [to the branches]."