Making Sense of Evolving WLAN Standards, Part 2: Radios and Centralized Architectures - Page 2

By Jeff Vance

January 22, 2004

The Future of Access Points

Of course, branch offices might best be seen as more accurately fitting into the consumer/SOHO segment, rather than the enterprise market, meaning a different class of equipment would suffice. When it comes to enterprise-scale deployments, though, many companies, such as Legra, Airespace, and others believe that APs must evolve. Whether far or thin, management features must be centralized.

"The only way enterprises will commit to large-scale WLANs is if they have the ability to control those deployments from a single device. Without centralized control over configuration, security, monitoring, and troubleshooting, the enterprise is faced with a management nightmare," Legra's Paul DeBeasi said.

"You can separate what you need in a WLAN AP into two components, and where those components reside is, to me, the crux of the debate," said Scott Lindsay, vide president of marketing at Engim, a provider of multi-channel WLAN chipsets. "First, there's the intelligence component, the brain if you will. Whether it's in the AP or a switch, I believe you need some degree of centralization to make your network manageable. Second, your wireless network needs sensors, or the eyes and ears of your network, and this component must reside in the APs. You could be fattening up the APs by providing additional sensing capabilities, enabling your APs to take in the most amount of information about interference, spectrum availability, and client types on the network, but you probably want the network-level control in a different device. Does that mean these are thin APs? I'm not sure that it does, because as more users enter the network, you'll need more radio-specific functionality available in the APs. From a networking standpoint, though, the APs will almost certainly get thinner."

As companies like Engim and Atheros begin to provide advanced radio-management features within the silicon itself, the APs based on those chips begin to look thinner still. Legra's DeBeasi takes the thin-AP argument a step further, arguing that leaving networking functions on the APs could bog down the network. As an example, he pointed to security, which resides on APs in traditional WLANs.

"We've pulled cryptography out of the AP because security standards are changing so quickly. A centralized encryption architecture is much easier to manage and upgrade. Access point-based cryptography is a legacy artifact from SOHO-based products. We believe that WLANs will be heterogeneous from a security standpoint for a long time to come, with WEP, WPA, IPSec, and eventually 802.11i all running at the same time. So your network infrastructure has to evolve to support that patchwork."

In essence, the only way to address these security issues in a manageable way is to centralize Layer 2 security, Layer 3 security, and policy management in a switch, otherwise critical security functions remain nearly unmanageable in large deployments.

DeBeasi pushes the thin-AP argument even further: "I see radios becoming essentially like intelligent antennas. They'll be like light bulbs, cheap and replaceable. Radios will get thinner, but they'll have to be managed by other intelligent devices. Before this can happen, though, there needs to be some sort of protocol that enables APs to communicate back to centralized appliances." Without such a standard, customers face a situation where they are locked into equipment from only one vendor, with each vendor concocting various proprietary protocols for AP-to-switch communications. Which brings us back to LWAPP.

Is Configuration Management a Looming Bottleneck?

While the Cisco worldview certainly can't be ignored, especially since Cisco is the leading WLAN equipment vendor by far, Legra, Airespace, and the other switch vendors seem to be on to a very important point: once you have a standard like LWAPP in place, then you have more flexibility in your AP deployments. You can deploy a switch from one vendor and APs from others, and you can also choose the latest AP for your network as it expands, rather than being locked into your initial choice for compatibility's sake.

All of this, though, depends on having a centralized network architecture. Without a centralized control device, it is much more difficult to upgrade your APs to a new security protocol, or any other protocol for that matter. Without centralization, enterprises will be faced with a manual process when it comes time to upgrade their installed base of APs.

"When vendors began to focus on the issue of configuration management in wired networks, they built that capability into switches because switches were the centralized resource," DeBeasi said. "In today's small consumer and SOHO environments, configuration management isn't a big issue. In tomorrow's massive enterprise deployments, configuration changes could bring upgrades to a grinding halt. When will network managers find the time to manually configure all of those APs?"

Supporters of LWAPP, argue that this standard will make the problem of configuration easier still. With the communications interface in place that allows switches to communicate with APs, it becomes easier to layer features on top of that basic communications layer, and, thus, it becomes easier to manage and configure a large installed base of APs."

In essence, the key to keeping up with the shifting standards associated with WLANs is to centralize them in order to manage them. This allows your network to remain open and flexible without becoming chaotic and impossibly complex. Moreover, your network has the ability to evolve as WLAN technology evolves, rather than becoming obsolete the minute you deploy it. However, not all standards can be relegated to the switch, of course. There has to be something residing on both APs and client devices, but with a switch acting as the command-and-control center of a WLAN, changes to any standard, even client standards, can eventually be controlled and managed in a centralized, orderly manner. In a proprietary, fat-AP world, the standards will do little to address the flexibility needed to keep up with the latest trends in the rapidly evolving WLAN world.

Jeff Vance is a technology writer and consultant. He was previously the editor of Mobile Internet Times and E-Infrastructure Times, before striking out as a freelance writer. He now focuses on high-tech trends in wireless, next-generation networking, and Internet infrastructure. His articles have appeared or are forthcoming in Network World, Wi-Fi Planet,,, and Telecom Trends, among others. You can contact him at

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