It’s too early for 11g

A few wireless vendors have decided to get a jump on the competition by releasing 802.11g equipment prior to the specification actually being ratified. By keeping their options open via software, these manufacturers hope to snap up a large chunk of the available 11g market now while still offering their customers full 11g compatibility, once the spec is approved, via firmware upgrades. This gave us a chance to get an early look at 11g, in the form of two consumer kits, before enterprise gear is widely available.

We examined two 802.11g access kits from Linksys and D-Link. Linksys sent us three WPC54G Wireless-G notebook adapters, two WAP54G Wireless-G access points, and one WRT54G Wireless-G broadband router. D-Link sent its DI-624 AirPlusXtremeG wireless broadband router as well as two DWL-G650 AirPlusXtremeG access cards.

Both broadband routers provide the same basic feature set, noncertified support for 802.11g, standard support for 802.11b, up to 128-bit WEP (Wired Equivalent Privacy) encryption, four autosensing 10/100 ports, and NAT. Both also provide a certain amount of content filtering based on conditions such as MAC (media access control) address, IP address, and URLs or domain names. However, neither has managed to make this filtering configuration overly intuitive even in their wizard interfaces, and both have aimed it directly at the home user rather than the corporate user.

This doesn’t mean these routers are entirely useless in an enterprise setting, though they would be relegated to remote office scenarios, especially for workgroups that frequently move or are located together only temporarily. For such situations, both companies have also included VPN pass-through capabilities — again aimed at the home telecommuter, but with enough horsepower to support a local workgroup if the need arose. You might also use this multisession IPsec support to implement roaming, but we feel there are better centralized solutions for this on the market today, such as those offered by BlueSocket and NetMotion Wireless.

Given these limitations on the router products, we decided to concentrate our testing more on access-point functionality and how they would integrate into existing network infrastructure. A key consideration is the issue of placement. Unlike other networking equipment, wireless access points can’t be hidden away in a switching closet. As such, the form factor of these devices needs to be both attractive and versatile.

Linksys lived up to these requirements, providing their not-unattractive typical purple and gray case that can be flat or wall mounted. If set up flat, the case can stack with other Linksys networking devices, such as workgroup hubs or their new wireless range-extender. D-Link’s router case (which is very similar to their access-point box) is also attractive and has wall-mount capability, though we found Linksys’ device much easier and faster to mount.

Configuring our access cards with the Linksys provided an additional wrinkle due to Linksys’ popularity. As it turns out, a neighbor to our lab was also using a Linksys 802.11b access point, which consistently showed up when we were scanning for connections. We separated the access points by renaming our SSID, switching off the default channel, and encrypting traffic.

Setup for both the D-Link and Linksys product lines begins with a CD-based installation utility. For access cards, that’s also where it ends, unless you delve into the Windows OS network settings dialogs. For access points and routers, however, the wizard configuration utility is backed by a Web-based administration server.

Solid management

We found browser-based management for both product lines to be generally quick and intuitive. Both allow for multiple administrator logins, but neither sport a logout button, so admins will need to remember to close their browsers. And while both products could manage multiple access points using this interface, we would have liked to have seen more features aimed specifically at this purpose, such as an overall access-point list page with basic connection information and some drill-down capability.

Even so, using the Web-based configuration utility, we were able to configure the D-Link to act as an access point on our existing 10/100 network and shared DSL connection. Unfortunately, while the D-Link’s documentation claims that the DI-624’s internal DHCP server can be disabled, this just didn’t want to work. We got around it by disabling our own Windows 2000 DHCP server temporarily, but you’ll want to check with D-Link’s tech support personnel prior to deploying the router in such a scenario.

Linksys’ access points proved to be little trouble. After configuring them to live within our existing 10.10.20.x addressing scheme, we were quickly able to deploy a single access point to communicate with our roving notebook test clients. We then set up two additional access points to act as a point-to-point wireless bridge between a 10/100 segment on the second floor of our lab building and a 10/100 segment in the basement. While Linksys has provided all the capabilities to do this, it’s not part of your basic documentation package. We managed it by segmenting addresses, using a separate channel for each segment, and digging deep into Linksys’ online knowledge base.

Shaky performance

Performance was a mixed bag for both products. Because of the overhead associated with the routers, we chose to confine their testing to simply increasing user load and monitoring connection rates. Both boxes fell below 20Mbps when handling more than four simultaneous sessions, but remained in this range at up to 10 simultaneous sessions.  

Where it got interesting was during mixed-mode testing. Both companies tout their products’ ability to support both 802.11b as well as their proprietary 802.11g implementations. We made sure to garner both a D-Link DWL-650H 802.11b wireless adapter and a Linksys WPC11 for this test, as well as an Enterasys RoamAbout card, a Netgear MA401 PC Card, and a Cisco Aironet adapter.

The D-Link access point was able to handle 802.11b connectivity from the Linksys, Netgear, and Cisco cards while also supplying 802.11g connectivity to its DWL-650H card. The Linksys access point, meanwhile, was able to provide 802.11b connectivity only to its own WPC11 card and the Netgear adapter. Neither product was able to handle WEP encryption outside its own product line where 802.11b was concerned, so cross-vendor testing had to be done with WEP disabled.

What really bothered us, however, was that in both cases connection rates dropped to less than 5Mbps for both 802.11b cards as well as their 802.11g counterparts. Thus, while “mixed mode” sounds like you can leverage 802.11g speed while protecting 802.11b investments, it actually means you’ll be buying 802.11g hardware to run at 802.11b speeds. Both companies claim to be addressing this limitation in new firmware releases, but the numbers remained the same even after we flashed Linksys’ router with the new driver software from the company’s Web site.

Distance proved another disappointment. In 11g-only mode, we were able to move up to 90 feet from our access point before losing our connection, but our connection dropped from 48Mbps, when within 6 feet of the AP, to 24Mbps when up to 35 feet away, and down to 15Mbps or less when more than 50 feet away — whether using D-Link’s or Linksys’ equipment. We got more than a 110-foot range with our 802.11b cards, but our connection rates never rose above 5Mbps and fell to less than 2Mbps at 80 feet.

While running wireless at 25Mbps or higher sounds attractive, our testing showed that it almost causes more problems than it solves in existing 802.11b wireless infrastructures. With mixed-mode capability limited to 802.11b and even that traffic considerably slowed, deploying 802.11g access points at this time seems unnecessary. Even when the 802.11g specification is ratified, distance capabilities will be less than 802.11b’s. That means more access points per site for complete coverage — another reason not to deploy until the specification is final.

For small offices or temporary sites where 802.11g will be the only game in town, these devices proved as effective as 802.11b and faster. But for integration into an existing infrastructure, they need some additional work and a finalized specification.