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802.11n Is Here. Get Ready For A Wire-Free Enterprise: Page 5 of 6

NEED FOR SPEED
Throughput is the first consideration when it comes to network connectivity, and 802.11n delivers: Both vendor and independent tests have shown that peak rates upward of 130 Mbps are achievable in good conditions. Advanced antenna designs, spatial streams, and multiple input/multiple output (MIMO) technology mean 11n also offers better coverage and improved radio frequency reliability and consistency. Access points can be spaced farther apart, if desired, but the better signal may more effectively be used to achieve higher access rates. Multipath, which previously degraded signal quality, is now used to good effect by MIMO to reduce the effects of fading and interference.

There are other benefits of 802.11n. First, it's essentially the fourth generation of the 802.11 standard, yet despite the evolution, each revision is backward compatible on both clients and access points, albeit at lowest common denominator rates. Companies can upgrade gradually because 802.11n clients work with 802.11a/b/g APs, and vice versa.

Second, as the market developed, amendments have been added to address deficiencies in the original 802.11 specification. The most significant are 802.11i, which deals with security, and 802.11e, which introduced quality-of-service features. Architectural approaches also have broadened. First-generation access points were standalone, with little to assist IT in terms of scalability, RF management, and Layer 3 roaming. Startups generally swung to the opposite extreme and centralized everything, leading to what pundits called "thin" APs.

With development of 802.11n and its higher traffic rates, a more sensible distributed approach, first used by Colubris in 2005, has evolved. The management plane remains centralized, as is common in any enterprise service framework, but the control and data planes can be placed at the core, edge switch, or access point. Motorola calls this "adaptive AP," while Trapeze has taken the moniker "Smart Mobile." Even Aruba, with its emphasis on centralized data flows, provides flexibility as described earlier with its Mobile Remote Access Point. Even if the WAN link is interrupted, connections stay up and local traffic will continue to be switched locally.

With 802.11n just around the corner, early adopters whose 802.11b/g gear is nearing end of life face a conundrum: Pay top dollar for 802.11n, stick with b/g, or add 802.11a support to their access points by buying new gear or moving to a different vendor. While 802.11a buys some advantages, at this point we recommend sitting tight until prices, AP maturity, and/or standard adoption are such that you feel comfortable upgrading to 802.11n. In fact, Aruba has a new marketing pitch: Buy its 802.11a/b/g APs today, and buy a key later to activate 802.11n. This approach helps customers split their costs over time--and assures Aruba market share.

It doesn't help purchasing decisions that the 802.11n standard isn't complete. Working group approval is tentatively scheduled for March 2009, many months past predictions. Vendor adoption of the draft 2.0 spec, along with all the pre-standard chipsets already in use, make it highly unlikely that a final standard that's incompatible with existing products will be adopted. Nevertheless, we can't argue the logic of waiting. Second-generation standards-based 802.11n products, even if functionality equivalent, will have many of the bugs and kinks--for example, 802.3af Power over Ethernet support--worked out. Prices will drop, and processes regarding site planning, installation, and maintenance will be better defined.

Enterprise network administrators also are concerned about reliability. Will that unforgiving terminal session or enterprise application drop every time the microwave goes on in the cafeteria? There remain a plethora of wireless supplicants, and connectivity is still not as certain as with Ethernet. With proper device selection and configuration, connectivity bugs can be minimized, but there's still room for improvement. Most users will trade a few connectivity blips for mobility. Some won't.

Voice Options For The Wire-Free Office
  Pros Cons
Softphone Works anywhere with wired on laptop or wireless connection; wide PBX support Laptop must be on to take a call; requires headset or earpiece
Mobile cellular phone Form factor and experience well-understood by users; variety of providers and pricing plans Indoor coverage typically challenging; no PBX integration; may not be acceptable for regulated industries
Voice-over-Wi-Fi handset Truly portable voice option; coverage wherever your WLAN reaches Few PBX vendors offer Vo-Fi systems; requires strict attention to RF design
e-FMC phone Best of both worlds that supports cellular and Wi-Fi Usually requires integration and sophisticated handsets; nascent market