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SD-branch network concept as next stage of WAN connectivity

SD-branch uses SD-WAN technology to simplify the branch network. It integrates multiple network functions now housed in separate components into software that runs in a single box.

Software-defined WAN technology is branching out.

More specifically, SD-WAN, coupled with evolving network architecture, is advancing a concept called software-defined branch, or SD-branch.

The SD-branch strategy is the next stage in SD-WAN's maturation, which has redefined how enterprises are connecting their branch sites to corporate- and cloud-based data centers.

Among other benefits, SD-branch aims to simplify how branch offices communicate with remote servers. Today, branch networks are crammed with components -- routers, firewalls and other appliances -- required to send traffic back and forth.

SD-branch would eliminate those separate devices in favor of a single conduit, said Roopa Honnachari, industry director for business communication services and cloud computing at Frost & Sullivan.

"Most of the branch functions you had in the past were hardware-centric, and you needed different hardware to deploy each of these functions," she said. "Now, you don't really need multiple devices or appliances for running multiple functions. Instead, one of these SD-WAN appliances can act as a single device for all of these different functions."

SD-WAN vs. SD-branch
How SD-WAN compares to SD-branch

At the same time, enterprises are changing the way they operate, turning to SaaS and cloud-based applications, while also relying more on internet of things. And those changes are placing more demands on branch networks.

"With the coming of the cloud, applications have moved to Amazon [Web Services] or Microsoft [Azure]," Honnachari said. "But the networks that were connecting the branch sites haven't changed accordingly."

SD-WAN took one of the first steps needed to improve that connectivity. Customers now have the opportunity to select multiple ways through which they can send and receive traffic, using technologies such as application-aware routing, network segmentation and other tools to improve performance.

NFV offers another approach to an SD-branch network

Instead, one of these SD-WAN appliances can act as a single device for all of these different functions.
Roopa Honnachariindustry director for business communication services and cloud computing, Frost & Sullivan

One step toward branch consolidation, Honnachari said, is transitioning functions formerly anchored in proprietary hardware and moving them to software.

"These same functions -- the router functionality, WAN optimization or security -- can now be deployed in software or virtual machine format," Honnachari said. "That's where the software-defined branch terminology comes into the picture."

The SD-branch network concept may also yield another way for enterprises to realize how technologies such as network functions virtualization (NFV) and SDN can be profitably deployed in remote offices, Honnachari said, citing packages of virtual network functions now being offered by providers like AT&T and Verizon.

"SDN and NFV have been known terminologies among the service provider and vendor side of the business, but the enterprise or business customers haven't really seen how [these technologies] materialize into meaningful value for them," she said.

Instead of using traditional dedicated appliances for different functions, enterprises can pick and choose whichever network functions they want at the branch, using a catalog-based approach, she added.

SD-branch network migration will happen slowly

While the quest for a thin branch -- a minimized hardware footprint in the branch -- isn't new, SD-WAN technology and processing-power improvements for hardware have made achieving a consolidated SD-branch network more possible, according to Lee Doyle, principal analyst at Doyle Research.

"Previously, we had single functions because we had to optimize for WAN optimization or routing or firewalls," Doyle said. "Now, we have enough horsepower with enough customized software to consolidate -- at least at the branch."

That doesn't mean hardware will disappear; branch locations will need some sort of physical device to run software on site. But Doyle -- and other analysts -- said enterprises can begin seriously studying the idea of reducing their reliance on dedicated appliances in the branch and moving toward a single appliance that supports multiple network functions.

"We're getting multifunction [offerings] from vendors," Doyle said. "That's the stage we're in now."

As with most technology resets, however, the SD-branch concept will be implemented slowly and in phases, Doyle said. In the beginning, SD-branch will primarily be available from existing network vendors that start incorporating a broader range of network capabilities into their offerings and appliances. Meanwhile, enterprises will probably wait for refresh recycles before making their moves.

"Now, you kind of have a branch in a box -- or a branch network in a box," he said. "Are all of those functions going to collapse all at once? No, probably not. But we're talking concepts and architecture here."

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