I wrote about building a wireless LAN for your SMB yesterday, where I talked about the need for a dedicated WLAN controller when deploying multiple access points (APs). As promised, I will present a general overview of how different vendors approach the management of multiple Wi-Fi APs today.
As WLAN vendors are constantly pushing the envelope with their products, what I'm detailing below should only be used as an approximate framework for initiating a more detailed discussion with your vendor of choice. It is certainly not meant as a cut-and-dry indication of the various capabilities and limitations of the current WLAN players on the market today.
Thin Access Point
Probably the most common deployment scenario at the moment, a thin access point is an AP bestowed with limited intelligence and managed by a centralized WLAN controller. Of course, the term "limited intelligence" is a subjective term, as practically all thin APs can operate perfectly well in stand-alone mode-which works as an upgrade path for smaller businesses or branch offices.
The use of a centralized appliance means that constant adjustments can be made to the RF (Radio Frequency) environment and the workloads of individual APs for optimal performance. And because all APs are known to the controller, unauthorized APs are also easily identified. Deployment is often as simple as first configuring the controller and then "rolling out" new APs by powering them up and connecting them to the wired network. Depending on your vendor of choice, a thin AP deployment can scale up to hundreds or even thousands of APs.
One downside here is that taking down the controller could bring the entire wireless network down. This risk is mitigated by using a separate controller to achieve fail-over reliability, though at the expense of further bringing up the capital costs required for an initial deployment.
Thick Access Point
Some vendors have opted to move away from the beaten path of thin access points, opting to incorporate greater intelligence and autonomy into their APs. The resultant "thick APs" incorporate many of the capabilities found in dedicated controllers, yet at a capital expenditure that scales linearly with the size of the wireless network. One vendor in particular, Xirrus, has decided to take this concept to the extreme, packing up to 16 separate APs into a single "Array" for high-density deployments.
The counter-argument, as you can imagine, is that thick APs merely distribute the cost of the controller across every AP. And because even thick APs can benefit from centralized management, vendors are known to offer software that essentially presents a user-friendly GUI from which to manage and configure multiple thick APs.
While widely used, the cost of a separate controller appliance can be prohibitive and is a barrier to adoption for smaller organizations. Progress has been made to eliminate or at least reduce this cost, and can be evidenced by controllers implemented using virtual machines (Bluesocket), or even controllers implemented directly into the AP (Aruba). Other vendors have also attempted to build the controlling functionality into existing hardware products, altogether eliminating the need to purchase a separate hardware. For example, Fortinet has incorporated Wireless Controller functionality into its flagship FortiOS operating system that powers its unified threat management appliances. Peplink, a maker of WAN load-balancing routers, also recently built the ability to manage its Pepwave AP One into the company's higher-end devices.
Proving that the WLAN field is one where innovation is taking place at a rapid pace, at least one company has decided to take the management of APs into the cloud. PowerCloud Systems in 2010 unveiled its CloudCommand technology that the company says allows networking equipment to be configured, deployed and managed from the cloud. The startup has at least one commercially available AP that supports CloudCommand (D-link DAP-2555), and Atheros Communications-a WLAN chipset heavyweight-also added the technology into its networking software platform in January. Cloud-based management of AP is definitely in its infancy at this point, though it may well gain traction in the SMB market for its advantages on the device management front.
Obviously, the WLAN controller is but a single facet of setting up a business WLAN. As with any acquisition, do take care to evaluate the relevant merits of a vendor and what works best for your company.