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Navigating the Shifting 802.11 Sands
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February 6, 2003
By Jesse Lindeman & Julio Caraballo
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IT decision-makers looking to build or expand their wireless infrastructures are caught in a whirlwind of evolving standards. Products based on the market-dominant 802.11b Wi-Fi (Wireless Fidelity) spec offer good range, low prices and limited bandwidth. Meanwhile, new 802.11a devices paint an alluring picture of fivefold throughput increases. We know it's tempting to abandon 11b, which runs at 11 Mbps, in favor of its faster sister, but your gains could be just a mirage because 11a products are expensive and not backward-compatible. The solution: Embrace both standards. And therein lies the beauty of dual-mode wireless access points.
We gathered devices from Cisco Systems, D-Link Systems, Intel Corp., Intermec Technologies Corp., Linksys Group and Proxim in our Syracuse University Real-World Labs® and tested their features, functionality, range and performance. Although all the APs support both 802.11a and 802.11b, as promised, some are more enterprise-ready than others.
Organizations that want to upgrade their existing 802.11b infrastructures will need to maintain backward compatibility; few can justify trashing their 802.11b equipment in favor of new 802.11a products. One option is to overlay single-mode 802.11a access points on the current 11b wireless network, but that setup can be unwieldy and expensive. Dual-mode APs, on the other hand, are easier to manage and cost far less than doubling up 802.11a and 802.11b APs.
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You can simplify new installations of any kind that require 11a/11b coverage--SOHO, enterprise or hot-spot settings--by using dual-mode APs.. For example, organizations that don't have WLANs (wireless LANs) may want to provide hot zones to cover conference rooms or cafeterias; a dual AP is ideal for this scenario. In addition, some of the devices tested add value by providing upgrade paths to 802.11g and beyond (see "802.11g Adds to the Mix").
Of course, there's a catch: The propagation characteristics are vastly different among radios, and, save for a few of the APs we tested, 802.11b coverage is far greater than that of 802.11a. In a dual-AP environment, proper design of 802.11b cells would leave large dead zones between 802.11a cells. This can be fixed by lowering the output power of the 802.11b radio, if the AP allows, so that the coverage areas are concentric, or by supplementing the patchy 802.11a network with single-mode 11a APs. Either way, this problem affects every dual-mode infrastructure and, while it will require time and money to solve, the cost for doing so is usually less than that of overlaying 11b and 11a devices.
Another big concern for wireless network administrators is security. Unfortunately, none of the APs we tested offers a groundbreaking solution.
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By the Numbers
In a Q302 ReefEdge survey of 935 IT networking and security professionals:
1st Position of 'security' on list of concerns
3rd: Position of 'cost' on list of concerns
9th: Position of 'interoperability' on list of concerns
57: percent said they have a wireless LAN deployment
85: percent of the remaining 43 percent said they have plans to deploy a wireless LAN within the foreseeable future
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Although WEP (Wired Equivalent Privacy) is a good basic security precaution because it's easy to implement and doesn't cause a performance hit, WEP's days are numbered. Most vendors promised that WEP's pending successor, WPA (Wi-Fi Protected Access, see an overview), will be supported through free firmware upgrades, but only Cisco provides a stand-in for the moribund WEP--TKIP (Temporal Key Integrity Protocol).
Finally, as in any wireless deployment, management is key. Most of the products we tested support SNMP--a step in the right direction. Enterprises with large installations of dual-mode APs will find Intermec's and Cisco's devices enticing because they offer central management suites that can be purchased separately.
With these issues in mind, we gave Cisco's Aironet 1200 AP our Editor's Choice award despite it being the priciest AP we tested: At $1,399, it's more than five times the cost of the least-expensive unit. In its favor, the 1200 offers an excellent mix of performance, range, ease of configuration and installation, and management options. Linksys' WAP51AB snagged our Best Value award because it held its own against rival APs in range and performance, all for just $279.
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