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SDN and wireless LAN meet for unified network management, at last

If SDN and wireless LANs both run on a controller-centric architecture, why not combine the two for unified wired and wireless network management?

There's so much vendor hype around software-defined networking (SDN), it can be difficult to separate fact from fiction. But when it comes to wireless networks, SDN is getting very little coverage at all -- even though combining the technologies could result in better unified network management and the ability to implement a more granular bring your own device (BYOD) policy.

Until recently, SDN innovators have focused on solving problems in the data center. There's been lots of attention paid to Google's self-built software-defined network, and plenty of vendors have launched strategies that would rearchitect the enterprise data center.

"[But] there's only a handful of vendors targeting the branch office where wireless comes into play," said Jim Metzler, founder and vice president of Sanibel, Fla.-based consulting firm Ashton, Metzler & Associates.

Yet SDN and wireless LAN architecture can be very similar depending on the strategy, so it only makes sense to integrate them.

In a software-defined network, "you have a controller that controls the action of network switches. The brains come out of the switches and go to the controller. That's what we've been doing with wireless for a long time," Metzler said. "Whereas in the data center LAN we're trying to wrap our heads around a new way of doing things, it's a relatively common architecture for wireless."

Centralized control in the wireless network emerged from the need to overcome complications, such as signal interference and providing coverage for moving clients.

"We started using a control plane ten years ago with an architecture of access points, and the controller was used to configure the network. It was a precursor of SDN, but with a smaller goal: Reduce the complexity involved with deployment and simplify management," said Isabelle Guis, founder and CEO of SDN Easy Consulting.

Integrating SDN and wireless for unified network management

The first step to integrating SDN and wireless architectures would be to unify the two controllers.

"Why can't an SDN controller and a wireless controller become one? If you can control physical switches and virtual switches, why not control access points [with the same controller]?" Metzler said.

Cisco is doing just that. The company's new Catalyst 3850 Unified Access Switch, for example, has a built-in WLAN controller and provides visibility and analytics across wired and wireless networks. The switch also has an application-specific integrated circuit that will support the Cisco Open Networking Environment (CiscoONE) SDN architecture. Eventually the entire Catalyst line will be working in the ONE architecture.

"We take the wireless traffic and at the access layer switch, de-encapsulate it, and from there it's straight Ethernet. All the SDN capabilities are available to wired and wireless traffic. … The beauty is it's transparent to customers. Traffic is traffic. Everything for wired is applicable to wireless traffic," explained Jeff Reed, vice president and general manager for software-defined networking and manageability at Enterprise Networking Group.

Once an SDN controller can obtain visibility and management of traffic across networks, engineers will finally reach the long-awaited goal of unified wired and wireless management.

"Right now we have two management systems -- one for wired and one for wireless. With SDN, we can take it to the next level and have a single management platform. Whatever services we have for wired, we can now have for wireless," Guis said.

SDN and wireless for tighter BYOD control

In addition to unified wired and wireless network management, applying SDN control to a wireless setting can be particularly beneficial for enforcing more granular BYOD policies.

"Better visibility up to the client helps you manage all those devices coming in that you don't necessarily know," Guis said. "Now you can enforce policy on the network itself." This includes user authentication, providing access to applications and setting different quality of service policies per user or per device, she said.

Reed gives the example of setting policies for different service set identifiers (SSIDs) using SDN controller visibility. "You might trust traffic from a specific SSID and allow it to bypass the firewall while others must go through the firewall. Being able to use SDN to make decisions like that is highly valuable," he said.

Enterasys' SDN technology, OneFabric Connect, is integrated with several mobile device management products to "enable customers to easily on-board mobile devices on the wireless side, but also enroll MDM on those devices and enable management at the network layer," said Ali Kafel, director of product marketing at Enterasys.

"By integrating with the MDM vendors, we're able to extend policy capabilities to these devices. For example, if an MDM-enabled device is jailbroken and the policy in the company is that you don't allow them in the network, or you restrict them to the Internet or certain servers or applications, that's the control we provide -- integrated management." Enterasys' SDN solution uses the OneFabric Architecture across all of its products to enable centralized network management and control of both the wired and wireless networks.

The future of SDN and wireless networks

More on SDN outside the data center

Where do we really need SDN? In the campus network!

Why the need for an SDN exchange?

Understanding the role of SDN in security

SDN for network management: More than just middleware!

SDN apps move beyond the data center

Unified wired and wireless network management and greater BYOD control are benefits of SDN, but is it enough to drive SDN adoption? "It's not clear that too many IT shops are going to rip out current access points and put new ones in place just to eliminate a controller," Metzler said. But as access points reach end of life and need replacing, it would make sense for organizations to consider equipment that can be upgraded in the future, he explained. In the meantime, as engineers consider investing in SDN, they should ask what wireless network functionality controllers provide since the technology wasn't originally designed to do that, he said.

The challenge with SDN for wireless, according to Guis, is that the wireless network is more complex than the wired. "Wireless has been adopted after wired, and now with BYOD it has to be a lot more specialized. There are big companies doing wired and a lot of companies doing wireless. It's hard to find one company that has a lot of expertise in both. A lot of partnerships are going to have to happen. Because wireless is a lot more complex, people will look first at [SDN for] wired and then extend it to the wireless network."

About the author
Crystal Bedell is a freelance writer specializing in business-to-business technology. Connect with her via LinkedIn or email.

This was last published in May 2013

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How will SDN impact the future of the WLAN?
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I think one of the advantages of using an SDN controller will be a centralized control over BYOD . You can manage the extent to which these devices can affect your enterprise network.
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Although having open programmability for Wi-Fi can be extremely useful -- Wi-Fi is moving away from a controller based model. Although controller based model works well for large single-site networks, it becomes prohibitively expensive and prone to outages in a multi-site, multi-branch network. The site-WLAN needs to work even if the site cannot connect to the centralized controller.

The DC situation is very different because controllers (one or more) control a pod or set of pods and if those pods go down, others will be available to take over while the original pod comes back up or is replaced.

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The real value of SDN and wireless LAN is creating an Open multi-tenant access layer and avoid all the independently managed access points
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