802.11n will boost speed, prompt upgrades

802.11n's speed will be a welcome boost for end-users, but will create headaches as admins face network upgrades to deal with the demand for bandwidth it unleashes.

802.11n is well on its way to being the next Wi-Fi standard. Last week, draft 2.0 of 802.11n was approved by an IEEE workgroup and could find its way into products as soon as later this year.

Heralded for offering faster throughput -- between 100 and 200 Mbps, and in some configurations up to 600 Mbps -- and better range than 802.11a, 802.11b and 802.11g, 802.11n is a significant step forward for Wi-Fi, experts say.

"This really is a big deal," said David Cohen, director of product marketing for wireless vendor Trapeze Networks.

But with increased throughput, up to four to five times that of 802.11g, 802.11n could result in clogged central switches and controllers that can't handle the huge jump in traffic loads.

Since every packet sent over 802.11n must pass through a switch or controller, that extra traffic has the potential to clog the gear, creating logjams and delay.

"As you migrate to 11n," Cohen said, "you can easily overwhelm the central switch or LAN controller."

Certain vendors, like Trapeze, make equipment that allows traffic to bypass the switch and LAN controller and flow directly through the access point. Others vendors, which do not offer that functionality, will play catch up.

"A lot of networks are going to have to upgrade their central switch and controller because they weren't built to handle that traffic," Cohen said.

Craig Mathias, principal with analystr firm Farpoint Group, added that enterprises will also have to upgrade to GigE switches to accommodate the additional throughput.

Another issue that enterprises should be concerned about is 802.11n's questionable compatibility with 802.11b/g legacy equipment, according to Forrester Research analyst Chris Silva.

"The major concern about 11n is the compatibility and its ability to play nice with legacy technology -- 11b and 11g," he said.

In a recent report, "802.11n: Too Early for Enterprise Adoption Today," Silva outlined some of the pitfalls of 802.11n. He wrote: "The 802.11n standard increases both speed and range of wireless networks; however, this is not a requisite update for most wireless environments. Given the investment required to ready an existing network for 802.11n, the potential for interference due to shared spectrum with legacy 802.11b/g access points and the potential for a greatly increased strain on the WLAN backhaul -- firms must consider carefully. Investing simply for an increase in speed begs a strong business case driven by applications, productivity and increased access to critical functions and applications by employees."

Benefits worth the upgrades

Trapeze's Cohen said 802.11n opens up the wireless network to support more applications, like video and voice, which under 802.11a/b/g didn't always get the full data rate. Real-time applications that are sensitive to delay will experience much less latency, if any at all.

With 11g, voice over Wi-Fi worked, but with only 54 Mbps available, voice would compete with other traffic and wouldn't always be given the data rate it required, introducing latency. With 802.11n, multiple voice calls and video streams can run concurrently and the traffic won't compete.

"And let's not forget poor old boring data," Cohen added. "You're going to get those files 10 times faster. You can have so much video, voice and data traffic running at one time."

802.11n also uses multiple input, multiple output (MIMO) for a broader range, surpassing the 100-foot reach of 802.11b and the 300-foot reach of 802.11g. Essentially, MIMO uses multiple antennae to send multiple data streams over the air between the client and wireless access point, converting them back into one stream at the destination.

"It's not just about data rates," Cohen pointed out. "It's also about range this time. You're going to be awash in radio signals."

Adoption strategies vary

Mathias agreed that 802.11n is a significant advance. He said it will have passed through the appropriate channels by year's end and be ratified. Cohen added that he expects final ratification by late 2008 or early 2009. While some products based on draft 2.0 will probably be available this year, Cohen believes that many enterprises will wait until final ratification to deploy.

But Silva said a lack of legitimate business drivers for rapid adoption could keep 802.11n on the back burner, with only a modest number of adoptions in early to mid-2009, which coincides with the normal three-to-five-year refresh cycle of enterprises using legacy 802.11g technology. He added that some vendors, such as Intel, with its Centrino Santa Rosa offering, are already starting to push 802.11n technology, so that by 2009, the penetration of client devices should be high enough to begin warranting a move to 11n.

"In advance of this, enterprises simply will not have enough client hardware in place to be able to take full advantage of the 11n standard's improved speed and range and will also be faced with 802.11 interference when using the technologies on the 2.4 GHz spectrum," Silva said.

According to Silva, vendors will quickly pick up on 802.11n and roll out technologies that position wireless as the main network an enterprise needs.

"Vendors are planning to message around the role of the WLAN as a primary network and are positioning 11n technology as a future-proofing for the WLAN," Silva said. "In other words, as enterprises ramp up their deployments of WLANs and start to look at things like widely deployed voice on the WLAN -- scenarios where dual-mode phones are employees' only phones -- video on the WLAN, and extension of the WLAN outside of the carpeted enterprise, vendors are largely positioning 11n as the only technology that can handle this. In terms of investing to support future use of the WLAN, I'd say that this message is not necessarily off base."

 

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