Cisco WLAN Controller Buyer's Guide - Page 2

Cisco's approach to its wireless controller portfolio reflects a desire to deliver flexibility to its customers, accommodating distributed and centralized WLAN architectures.

 By Lisa Phifer
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Centralized control, decentralized traffic

When it comes to defining where WLAN controllers sit within each customer's network, Kozup said Cisco's strategy is to do it all. "Does traffic have to be sent back to a central switch or not? We support both," said Kozup. "H-REAP (Hybrid Remote AP) technology, supported by all of our APs, allows organizations to centralize control plane functionality, such as configuration and policy, at the data center while still distributing switching functionality."

For example, a large retailer could centralize control by deploying a 5500 Series Wireless Controller or WiSM at the data center. It might also deploy one or two APs per store, without branch controllers. Those in-store APs maintain links back to the data center for WLAN control. "In event of a WAN outage, those APs can survive," said Kozup. "Over time, functionality degrades -- for example, you can't authenticate new clients -- but for the duration of most outages, those networks are highly survivable."

When customers choose to tunnel traffic back to a controller at the data center, they get to decide whether or not it gets encrypted. "Retail stores might connected using private WAN links that are already secured, but teleworker APs might establish encrypted tunnels back to their enterprise's wireless controller, letting the same enterprise SSID be used at home and office," he said.

Although the controller can participate in the data path, Cisco views the controller primarily as a control plane services platform. "Its primary function is to scale and simplify security, letting one-touch changes made at a management console (WCS) be replicated throughout the network," said Kozup. "We use the now-standard CAPWAP protocol to relay changes made through controllers, out to APs."

Cisco controllers also support security functions, such as guest segmentation and bandwidth policies that limit guest traffic. "They enforce security profiles that determine encryption applied between APs and controller, and QoS handling - for example, applying VideoStream technology to distribute video more effectively across wireless. Our controllers optimize application delivery while maintaining central control and configuration over APs."

Bottom line

According to Kozup, one key advantage of Cisco's controller approach is that customers are not forced to adopt a specific WLAN architecture. "With H-REAP, we have the flexibility to support both distributed and centralized architectures. And our portfolio includes both integrated and stand-alone products that offer the same set of advanced control services." To learn more, visit Cisco's Unified Wireless Networks page.

Lisa Phifer owns Core Competence, a consulting firm focused on business use of emerging network and security technologies. An avid fan of all things wireless and frequent contributor to Wi-Fi Planet, Lisa has reviewed, deployed, and tested 802.11 products for nearly a decade.

This article was originally published on Feb 18, 2011
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