By John Cox
Network World, 09/24/01
Wireless LANs are about to experience a boost that will give
them enough throughput to handle all but the most bandwidth-hungry corporate
applications. Yet security, network design and cost could be speed bumps to
acceptance.
By the end of this year, more than a dozen LAN vendors will
introduce the first wireless LAN access points and interface cards based on
the IEEE 802.11a standard, approved in 1999. These products will use the 5-GHz
unlicensed radio frequency and reach a variety of speeds up to the 802.11a
maximum of 54M bit/sec. By contrast, today's nets, based on the 802.11b
standard (also approved in 1999) use the 2.4-GHz frequency and have a maximum
speed of 22M bit/sec. Some vendors, such as Proxim, promise an optional and
proprietary mode for their 11a products to boost speed to over 70M bit/sec.
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A radio modulation technique called Orthogonal Frequency Division
Multiplexing (OFDM) is the source of 11a's higher speeds. OFDM divides one
high-speed data carrier into 52 low-speed subcarriers that transmit in parallel.
These subcarriers can be bunched much closer together than is possible with
the frequency division multiplexing, spread spectrum technique used in 11b.
So transmission is more efficient and yields higher data rates on 11a nets.
Other differences between the specifications include radio
ranges, antenna designs, security add-ons and network management features.
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What to ask 802.11a wireless LAN vendors
How can I migrate from 802.11b to
your 11a products, and how will you minimize migration
costs?
Will your 11a products support the
maximum 54M bit/sec speed specified by the IEEE standard?
What additional wireless LAN security
will you offer, particularly for stronger encryption
and authentication, above that specified by 802.11a?
Can I configure and manage access
points and interface cards remotely, instead of manually?
If so, how?
What is the status of all necessary
software drivers to support my mix of wireless client
devices?
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Many of these differences will only be apparent, and measurable,
in pilot tests. Because the same products can perform differently in different
sites - depending on construction materials, user numbers and other variables
- such pilots will be the only way to tell if you'd need more 11a access
points than 11b, for instance. Theoretically, higher bandwidth means shorter
range. But Rich Redelffs, president and CEO of 11a chip maker Atheros Communications
of Sunnyvale, Calif., insists there is in fact little difference in range
between the two, at least for 11a products based on the Atheros chipset.
Both standards also share the same security issues. A wireless
protocol sniffer can grab the wireless LAN network name, which works as a
kind of network password, and it can grab unencrypted media access control
(MAC) addresses, which identify nodes already authenticated on the wireless
LAN. Most LAN card drivers let the card's MAC address be changed, so attackers
could set their own card's address to be the same as a node already on the
wireless LAN.
Likewise, the Wired Equivalent Privacy encryption scheme used
in 11a and 11b has been criticized for weaknesses that could let a sophisticated
hacker decrypt the traffic.
These
security issues were spotlighted in August
when three leading cryptographers discovered a relatively simple way of recovering
the WEP encryption key, which is created by the RC4 cipher to scramble and
unscramble traffic over an 802.11b LAN. The discovery underscores the fact
that wireless security is ultimately an enterprise IT responsibility.
And closing such security holes requires adding a firewall,
a VPN and a different encryption scheme. All that also adds complexity and
administrative overhead.
"I'd hope the 11a products would avoid the security issues
of 11b," says Dennis Moul, IS manager for CoManage, a Pittsburgh vendor
of telecom management software. CoManage has installed a Lucent 11b wireless
LAN, used by 30 to 40 of 100 users, in and across three buildings, as an overlay
of the wired LAN. "It's just a hassle to do firewalls and run VPN connections.
If we have to do that with 11a LANs, it will be a stumbling block to their
adoption."
Yet this remains what vendors recommend for the upcoming 11a
products.
Big competition
No vendor dominates the comparatively tiny 802.11b market.
The total wireless LAN market is expected to be $1.4 billion in 2002, and
$2.2 billion in 2003, according to a July report by Micrologic Research. Sales
of 11a products aren't expected to start growing until 2003, according to
Micrologic President Jack Quinn. By contrast, IDC estimates the revenue for
wired Gigabit Ethernet modular switches alone to grow from $5.4 billion in
2001 to $7.9 billion next year.
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In good company
While the 802.11a is closest to commercialization, two other wireless LAN specifications also are nearing completion. Even as 11a products near release, other high-speed options are encroaching. The European Telecommunication Standards Institute (ETSI) is finalizing work on the HiperLAN II specification, which, like 11a, operates in the 5-GHz frequency and has a maximum rate of 54M bit/sec. The first products are expected in Europe next year. The ETSI and IEEE are working on a project to let products based on the different 5-GHz standards work together, avoiding interference.
Meanwhile, 11g is being finalizing by the IEEE and will boost speeds on 2.4-GHz nets to 22M bit/sec. No LAN vendors have yet announced 11g plans, although some chip makers say they will create chipsets for it. 11g LAN products therefore could materialize around late 2002.
—John Cox
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Still, the usual big-league players from the wired world all
plan to compete aggressively with 11a: 3Com, Cisco, Enterasys and Lucent's
Agere, all of which offer 11b products. Several vendors bought existing 11b
wireless product lines or start-ups. In February, Cisco purchased one of the
key 11a chipset makers, Radiata.
Other players include much smaller vendors of 11b products,
but with long experience in proprietary wireless LAN design, deployment and
support: Intermec, Symbol Technologies and Proxim among them.
Pricing predictions have been dropping in the past few weeks.
Until recently, most analysts and vendors said 11a products could cost twice
as much as 11b offerings, with access points that can support 20 to 40 clients
starting at about $1,000 to $1,200. Current 11b access points can be as low
as about $600.
But several vendors have
hinted that they will price the new breed of products far closer to that
of the old. Intermec and Proxim, which are using the Atheros chipset, and
Symbol, which is using one it co-developed with Intel, say they expect users
will pay only a small premium for 11a products over 11b. Proxim, for example,
will introduce by year-end an 11a access point and a PC Card under its Harmony
label, with pricing "similar" to the existing Harmony 802.11b products:
the Harmony 11b access point is $600, the 11b PC Card is $200.
But price alone is unlikely to usher in widespread adoption.
Security, management and product quality remain question marks.
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