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 |
GOTCHAS REMAIN
Despite all the performance and other benefits of 802.11n, there are still questions about reliability, performance, legacy devices, integration into the existing wire-centric infrastructure, and market dynamics.
RF remains a black art, and although MIMO makes Wi-Fi more reliable, it's still no guarantee that interference won't interrupt. For starters, good planning is required, perhaps using a tool such as Cisco's Spectrum Expert (formerly Cognio), which identifies possible sources of interference. There are also architectural approaches to address the reliability problem. Meru's newest 802.11n access point, the AP400, was designed for robustness. Its four built-in radios can operate simultaneously, on different channels; interference on one channel or band doesn't prevent a client from roaming to another radio. Another approach, used by Ruckus Wireless and Xirrus, is to employ directional antennas. These approaches are still considered a bit unconventional, but they're worth watching.
