802.11g WLAN gear

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The lack of a final standard hasn't prevented an early crop of 802.11g wireless LAN products (54M bit/sec, 2.4-GHz frequency) from coming to market. We obtained seven prestandard access points and put them through their paces. This gear is pointed largely toward home and small business markets, and the product features show it. This first group is far faster than pure 802.11b, yet slows quite a bit when 802.11b clients try to access them. They show promise, but our results will change when a final standard brings compliant firmware upgrades.


Securing 802.11g

The 'Frankenstein' spec

How we did it

NetResults

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We tested products from AppleBelkinBuffalo TechnologyD-Link SystemsLinksysNetgear and SMC Networks. Buffalo's products hit our doors first - and, like many of the participants, the company followed up with several CDs or fat firmware files worth of revisions in the three months after products were released.

The D-Link DI-624 and Belkin's 54g products win our Blue Ribbon Award - Belkin's installation, management and performance were very good, and in terms of raw performance, D-Link's DI-624 was positively blazing - outdistancing the competition.

But are any of these products ready for production deployment? The answer is mixed. With the 802.11g specification still in draft form - it's unlikely that any of the products reviewed will have the same firmware after the final specification is agreed upon this summer. All these products are upgradeable, but it's difficult to tell how the changes will affect performance. At the time we conducted our test, the products lack ed support for the upcoming Wi-Fi Protected Access specification (see "Securing 802.11g"), so high security is up to third-party authentication schemes.

Speed and range

Because 802.11g uses the same radio spectrum as 802.11b and also provides optional backward-compatibility with 802.11b, 802.11g is perceived as the successor to 802.11b (See "The 'Frankenstein' spec").

The draft specification provides for speeds up to 54M bit/sec, but in testing we found on average about 14.97M bit/sec of speeds. The difference between the gross speed and our average results is similar to the differences seen in 802.11a and 802.11b products - signaling overhead eats up a large fraction of performance (roughly more than one-third off the top). The data rates with 802.11g can be blazing compared with 802.11b. D-Link turned in the best optimized speed, with a 24.73M bit/sec rate.

But these speeds often are compromised if an 802.11g access point is in dual-mode 802.11b/g - because the access point will fall back to the slower data rates if there's an active association with any 802.11b device. Some access points were more sensitive to fallback data rates and might be perceived as slower as a result. For optimum results (and for the basis of grading performance), we used the products' pure 802.11g modes where available.

When an 802.11b client was used (various 802.11b-only cards) in close proximity to the access point, data rates would drop back to 802.11b levels. Mixed mode performance drops are typical and part of the draft standard. This effect likely will continue to change until stabilized under the final standard when it is agreed on in the early summer. Because of the expected changes that will take place in the standard, speeds are likely to change when subsequent firmware arrives for each access point.

Geographic coverage was fairly uniform across the products when set in the strict 802.11g mode (where possible). D-Link's DI-624 had the largest range (344 feet), and Buffalo's gear had the smallest radio range (about 213 feet) before signals degraded to uselessness. In 802.11b/g mode, the range for all of the access points was smaller - on average about 279 feet. There was not much of a range difference between 802.11b and 802.11g modes, although our speed fell back slower in the pure 802.11g modes as we moved away from the access point.

D-Link Xtreme G DI-624

D-Link's Xtreme G is an access point and four-port router that can be set up from a browser interface or CD. There is a choice of a setup wizard for non-techie and another method with advanced settings. Xtreme G had the fastest throughput of the access points we tested - on average about 24.73M bit/sec, with a peak of 26M bit/sec (albeit with a Buffalo client card).

Security isn't strong on the list of features, although it includes Wired Equivalent Privacy (WEP) (64- and 128-bit encryption); filtration of users by media access control or IP address; port blocking; time-of-day access by MAC or IP address; and URL and domain blocking. A rudimentary "firewall" also can be used to create admit/ deny rules based on traffic behavior but falls short of stateful packet inspection and preset rules-based firewall applications.

Xtreme G had the largest usable radial air space range of all the access points tested in pure 802.11g mode, but it wasn't the fastest in the 802.11b/g mixed mode measured with 802.11b clients. However, this access point had strong raw speed and range - both strongly desirable characteristics.

Belkin 54g

We were dazzled by Belkin's installation applications for its 54g access point. The CD-based application had almost no options, except for the checkbox to agree to the license agreement. More setup options are available via the browser access to the hardware. The 54g is a four-port router and access point, and the installation application figured out the network infrastructure of our labs, found the router, grabbed a Dynamic Host Configuration Protocol (DHCP) address for it, invoked network address translation (NAT) and woke up the access point in ready-to-run mode. The only downside is its browser interface has no default password or user name. Otherwise, it was the easiest setup for a non-techie or network installer that we've ever found in an access point. The browser interface that the Belkin 54g uses is an equal to the CD-based setup program.

Configuring the access point was easy - features include a firewall and "parental control" functionality. Two modes are available - simple access point, or access point/router. We did all our tests in the access point/router mode. The device also can be managed remotely via a single-stated remote IP address via its WAN port. This was potentially handy, but the weak security of the device (it requires only a password) could make it vulnerable to a dictionary attack, where various words are progressively substituted until the password is cracked.

We were pleasantly surprised to find that the access point could search automatically for updates to be presented for use after the next access point browser interface logon. This feature was unique among the access points tested, and given the pace of firmware updates, this feature is highly desirable.

The device's throughput performance was average, and it showed a linear decrease in speed over distance in our walkabout testing.

Linksys WRT54G

The Linksys WRT54G access point and four-port switch/router uses a CD-based wizard for setup, and also can be set up via a Web browser. The wizard was good at guessing the network infrastructure of our lab, but wasn't quite equal to Belkin's wizard. However, users are unlikely to hurt themselves with this.

The WRT54G doesn't contain any strong firewall features. Security consists of WEP, MAC-layer access control lists, filtered ports, time-of-day access by MAC, and VPN passthrough support for Point-to-Point Tunneling Protocol and IP Security-based LANs.

The device came in second for its performance, and the performance was consistent across all our tests - in mixed mode (802.11b/g), the access point had the fastest performance.

SMC2804WBR

SMC crammed bridge, routing and firewall applications into its SMC2804WBR access point and four-port router. It is compatible with Windows and Apple 802.11b/g networks. The 2804, also known as the Barricade g, can be set up via wizard (civilians) or with Advanced Setup. The CD wizard application flashed SMC products as advertisements, reminding us of our distaste for commercials before the movie starts.

The advanced setup includes options for system control functions, WAN/LAN setup, wireless configuration (Service Set Identifier and choice of pure 802.11g or 802.11b/g mixed mode). The 2804's twin antennas are removable, and can be replaced with other wireless LAN antennas designed for 802.11b gear.

The firewall control uses a combination of access controls, coupled to a stateful inspection. Various combinations of features also can be enabled to increase security via a user-defined filter table, MAC filtering (admittance), specific user-defined URL blocking, scheduled access and intrusion detection (blocking). The default settings were adequate for most small office/home office (SOHO) users. The browser interface makes poor use of screen dimensions, which made log viewing difficult.

The performance of the SMC was linear in our walkabout test and, like other units tested, fell back to 802.11b speeds when an 802.11b device was associated with it. In the pure 802.11g mode, performance was near average.

Netgear WG602

Simplicity sometimes can mean bliss - the WG602 is a simple, no-frills access point without SOHO features. The setup was one of the simplest of all the units tested, if only because there aren't many features and options to choose. WEP is supported, both 64- and 128-bit.

Like other Netgear access points, the WG602 is accessed via a browser interface. Because this isn't a SOHO product, setup is focused more on network personnel. We couldn't find a way to force the WG602 into a strict 802.11g mode, although when 802.11b clients were around we didn't find the bandwidth cannibalization normally found.

We thought that the Netgear 802.11a/b/g adapter card would run most quickly with the WG602, but oddly it was the SMC wireless LAN card that performed best with it. WG602 also had linear performance in our walkabout test, and was an above average performer in the mixed 802.11b/g mode (again, we couldn't be sure that there was a pure 802.11g mode).

Buffalo WBR-B11/G54

The Buffalo AirStation was the first 802.11g device we received, and we had three revisions of the firmware in three months of testing. The AirStation can be configured through a bundled CD. After installing the utilities, wireless LAN adapter and/or manuals, the device can be configured via browser.

AirStation is a hybrid access point/gateway/router/switch, which left choices similar to SMC's access point initially - for DSL, cable or an "advanced" setup. The DSL and cable selections worked well for civilians, and the advanced setup can be used to move the default IP address to another. But this time, the new address is kept as a link on the page, so that when the access point reboots, the new IP address of the access point can be selected easily. We liked this thoughtfulness because other browser-based applications aren't that smart. Another handy feature is the autosensing WAN port, which can be connected to a router or hub port - it figures out the difference and adjusts within 3 seconds to the correct electrical wiring needed.

AirStation had nonlinear fallback performance in our walkabout test as it would leap back and forth in speed trying to adjust to increase/decrease signal, and we lost association in 802.11b and 802.11g modes after about 98 feet. An external antenna jack is provided for adding an antenna, but we did not test this feature. The overall performance in both modes was average.

Apple AirPort Extreme AP

AirPort Extreme must be configured from an Apple computer and has no browser interface. We updated the resident AirPort administration software on a PowerBook G4 running OS/X 10.2 from the enclosed CD. AirPort Extreme is a one-port gateway/router; the Administration software found the AirPort Extreme and configured it correctly for the network that we had connected its WAN port to.

We found some subtle limitations. AirPort Extreme limits its DHCP NAT range to a 10 address range - outside of the range we use in our labs. DHCP can be configured to proxy the DHCP connections otherwise. There is no firewall application, although the AirPort Extreme has MAC address filtering available.

AirPort Extreme also contained an optional modem that can dial in to an ISP to effect an Internet connection (to an ISP or AOL specifically), although the AirPort can't be programmed to fail over to a dialed connection if the WAN connection fails. There's also a USB port on the AirPort for shared devices such as printers.

One strong upside to the AirPort Extreme is the ability to force clients into using a Remote Authentication Dial-In User Service (RADIUS) server. While not a full-blown 802.1X authentication framework, this added authentication step is welcome, and worked correctly with our lab's RADIUS server.

AirpPort Extreme had good performance in our speed tests, but the range was slightly below average. An external antenna port is available, which might optionally increase range.

Conclusion

Prestandard 802.11g products are targeted largely at home and small-business use, and don't have the emphasis on access-point-based security features seen in products poised toward industrial and campus use. The 15M to 25M bit/sec data speeds offered by 802.11g in our tests is far faster than the 4M bit/sec speed of 802.11b. It is probably safe for early business adopters with their own mutual-authentication security infrastructure to start dabbling in 802.11g - the speed gains are immediate in homogeneous 802.11g networks.

Those with mixtures of 802.11b and 802.11g will find that access points uniformly slow to accommodate the slower speeds of 802.11b, but still will get benefits. This includes the ability to service areas with a higher concentration of users to a single access point, as the 802.11g MAC layer is still Ethernet, which likes quick and tidy transactions.

While 802.11b won't go away for a while, many companies might feel that the superior speed potential of 802.11g and its backward-compatibility with 802.11b warrants dropping 802.11b in favor of 802.11g (or even 802.11a or the hybrid 802.11a/b/g equipment). Perhaps, in a year, this will be true, once the standards have finalized.

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Henderson is principal researcher for ExtremeLabs, of Indianapolis. He can be reached at thenderson@extremelabs.com.

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