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Moving Forward with 802.11a

The 802.11a standard is shaping up to become the next wireless tsunami. We explore this and other technologies emerging in this exciting wireless frontier. by Seamus Phan

The IEEE body is facing an uphill struggle to get the 802.11g specifications ratified quickly so that vendors can officially launch faster 22 Mbps 802.11g products. It may appear that commercially available products would not appear at least until the end of Q1'02. At the same time, 802.11a, the much faster brethren of 802.11b (and 802.11g) seems to be on track, with or without IEEE's ratification.

The reasoning behind 802.11a is simple. Beyond the higher speeds of 54 Mbps (and higher), 802.11a utilizes the 5 GHz spectrum, which is pretty much unused, unlike the overcrowded 2.4 GHz used by 802.11b. 2.4 GHz is used not just by 802.11b wireless LANs (WLANs), but also Bluetooth (the laggard short range wireless communication standard), as well as consumer devices such as cordless phones, audio/video wireless transmitters, and microwave ovens.

For example, some major 802.11a chip makers such as Intersil ( and Atheros ( have announced more affordable 802.11a chips going around $35 per chip, which would certainly help alleviate OEM startup and process manufacturing costs to launch commercially-available 802.11a products quickly.

Intersil announced its $35 Prism Indigo silicon germanium/CMOS chipset in June 2001, in response to Atheros' pure CMOS 802.11a chipset going at the same price.

Bridging Old and New
Given its farther range and relative affordability even when compared to wired LANs, 802.11b technology has been aggressively deployed in recent months. Thus, the pure 5 GHz vendor camps advocating 802.11a only adoption will face corporate resistance as many have had only recently adopted 802.11b WLANs, and are still trying to recoup their investments.

Bridging technologies such as those from startup Envara ( will enable corporations to retain and maximize their 802.11b infrastructure, while slowly upgrading pockets of their WLANs with faster 802.11a technologies with backward compatibility at all times.

Envara has announced that its low power chip set will cost $35 per chipset (containing both 802.11a and 802.11b chips), thus offering a much more attractive option for laptop makers and OEM WLAN vendors.

Wired LANs may have lower startup costs, but face ongoing maintenance and upgrade costs, especially in a dynamic employment landscape where employees shift departments or become teleworkers. Companies face location changes more frequently these days, and WLAN technologies can reduce maintenance and startup hassles in these scenarios.

Built-in Security
802.11b WLANs have been hit again with another form of possible intrusion. This new form of intrusion can be used to gain unauthorized access to otherwise protected workstations running on wired LANs. This is done illegally by using the base station connected to the network switch or hub, using an old intrusion technique called ARP cache poisoning (address resolution protocol).

Once the wired network is intruded, the intruder can monitor and manipulate traffic between wired and wireless hosts behind a firewall, compromise roaming wireless clients attached to different base stations, monitor and manipulate traffic between wireless clients.

In short, ARP cache poisoning can disable firewall-protected networks. To avoid this, leave your WLAN outside the firewall and treat it as unsafe, and authenticate the wireless clients through a comprehensive VPN.

For the paranoid, better security measures will be available around early 2002. One innovative vendor is Resonext Communications (, which has introduced the RN5200 family of 802.11a chip sets that will incorporate 802.11i, which is IEEE's security specification for WLANs. 802.11i is still not yet ratified, but Resonext has already announced that their chip sets will be guaranteed compatible with the 802.11i specification.

This is a significant development that will help to shore up 802.11b WLAN security. Until now, most security analysts would advise leaving WLANs outside the firewalled zone, and treating all WLAN users at the same security clearance as remote access users. VPN technologies are also frequently recommended for authenticating WLAN users before allowing them into networks and accessing corporate information.

Ready, Get Set, 802.11a
Besides chip set advancements in 802.11a and other related technologies which make 802.11a safer and more efficient to use, there are also a host of 802.11a commercial products that will be available soon.

Proxim, one of the pioneers in 802.11b technology, has announced its Harmoney 802.11a adapter and base stations, which will comply with standard 802.11a specifications for data traffic at 54 Mbps, while providing a proprietary 108 Mbps speed called the 2X mode, for conference rooms, classrooms or office environments.

The company says that its Harmony range will support security standards such as RADIUS and 802.1x port-based authentication (found in Windows XP, as well as many new switch products). Harmony also provides per user and per session dynamic WEP key distribution (running at 40, 128 and 152-bit encryption) for added security. Because WLANs are supposed to be in the DMZ (demilitarised zone), Proxim also includes VPN tunneling and access control list (ACL) features.

Another feature, carried over from the 802.11b camp is "Power-over-Ethernet", which provides base stations the ability to carry electrical power over standard Cat-egory 5 cabling up to 100 meters with no degradation in network performance. This is exceptionally important as corporations migrate to 802.11a, since 802.11a will require a far higher base station density or population, and revamping the power grid will involve more expense, manpower, time and disruption to work.

Modern base stations also offer either a Web-based (preferred) or a proprietary GUI to configure them. In the case of Proxim's Harmony, they can be configured from a standard Web browser. Other base stations may offer a Java utility, or a Windows, Mac OS or Unix/Linux GUI utility, to configure them. A recent competitor to Proxim is SMC Networks (, which announced the availability of 802.11a compliant EZ Connect base stations and card adapters.

SMC's EZ Connect products will also deliver performance at 54 Mbps in standard 802.11a mode, but its "enhanced" mode will offer a data rate of up to 72 Mbps (in what SMC termed as the "Turbo mode"), as opposed to 108 Mbps from Proxim's Harmony. EZ Connect's WEP encryption schemes are somewhat different as well, offering a base bit rate of 64, and scaling to 128-bit and 152-bit.

SMC's offerings also adds MAC filtering, a feature that is quite common with most 802.11b and future products, such as 802.11g and 802.11a. MAC filtering will provide another limited way to restrict unauthorized entry and usage, by registering the legitimate MAC addresses of the card adapters on the WLAN. However, there are ways to spoof MAC addresses, break WEP keys and intrude on the network.

What of the Future?
Down the road, we would probably see the likes of Symbol ( moving its current VoIP wireless phones that run on 802.11b to newer standards, including 802.11g and 802.11a. This makes commercial sense as 802.11a and 802.11g will adopt Quality of Service (QoS) and security standards through the 802.11i and 802.11e standards, respectively.

Even as vendors tout 802.11a as the frontier and future of wireless networking technology, we should approach 802.11a with cautious optimism. This comes with the view that Europe and Japan have already voiced objection to the US-centric 802.11a 5 GHz standard, opting for their own alternatives. Even though 802.11g faces a continued struggle to reach ratification within the fragmented IEEE, in the short to mid-term, 802.11g may present far less regulatory obstacles to corporate adoption en masse.

Nevertheless, we should see some clearing of the sky with regards to these WLAN standards by the end of the Q1'02, and should be able to strategically position your WLAN plans by then.


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