Double-duty APs

As wireless LANs begin the long transition from 802.11b to higher-speed alternatives, dual-mode APs (access points) can protect previous investments while offering the advantages of newer technology. Proxim’s Orinoco AP-2000 with 5GHz adapter is the latest enterprise-class 802.11a/b wireless LAN access point to come across our bench.

When the AP-2000 is combined with Proxim’s Wireless LAN Manager software V1.3.2 — an updated version of the Orinoco Wireless LAN Manager software that we reviewed last June — and the Orinoco 802.11a/b ComboCard, the result is a wireless access system that lets network users take advantage of wireless connections using either of the two major WLAN standards currently in place (see “WLAN overboard,” June 10, page 19). For medium and large enterprises, the combination is a readily managed, security-friendly network that has superb radio performance.

Access point particulars

The AP-2000 is one of the more versatile access points around because its default configuration is no radio at all. The basic box has the switching circuitry, power control, 10/100base-T Ethernet and serial console ports, and two PC card slots for WLAN NICs. The two slots can contain one or two 802.11b cards, one 802.11b and one 802.11g card, or any combination of radio protocols that may be developed in the future.

Both radios may be set as access points, providing a wireless link to the network connected to the cable Ethernet interface; or one access point may be set as a bridge, receiving a network connection through one port and sharing it on the other.

Bridged installations are important to those installing wireless networking in older facilities — where the cost of pulling cable can be prohibitive — whereas simple dual-mode installations are critical to quieting the roar of users always searching for the fastest connection to the network.

In our review configuration, we had one slot filled with an 802.11b card and one with the Proxim 5GHz Kit, which included an 802.11a NIC connected to a pair of antennae locked into a unit that clips onto the AP-2000’s mounting bracket. Despite adequate documentation, we still found ourselves in a “Christmas Eve, 2 a.m.” state of mind after turning pieces this way and that to slip tabs and hooks into the correct slots.

Once everything is in the right place, you have a solid unit with 5GHz antennae that swivel to adapt to the access point’s mounting position. In our unit, the 802.11b card used its internal antennae, which performed perfectly well in our office environment. If the 802.11b side of the AP was being used as a bridge, an external antenna, which is an option with the Orinoco NIC, would be needed for best performance.

We evaluated radio performance using the AirMagnet Duo and found that signal strength was similar to that of the Cisco Access Point 1200 with 5GHz adapter that we used for comparison. 802.11b maintained 11Mbps links within the limits of our office (approximately 60 feet at the furthest point); 802.11a maintained a link over the same distance though the connection speed dropped to 26Mbps at the office boundary.

The AP-2000 is managed through either a serial console or a browser interface connected via Ethernet. Using the browser interface, we found that controlling configuration functions was a straightforward process facilitated by easy navigation through well-organized tabs.

But as with most browser-based interfaces, you need to be aware of which browser you use. We found that AP-2000 worked well using both Internet Explorer and Mozilla. Key functions were not accessible when using Opera, however. For example, buttons to configure individual parameters displayed properly in Opera, but the Java scripts to call the parameter pages would not execute.

Security functions built into the AP-2000 include MAC-address and RADIUS (Remote Authentication Dial-In User Service) authentication, VPN support, 802.1x (40- and 128-bit), and WEP encryption (40- and 104-bit) — pretty good access points go. In addition, filtering rules can be used to limit protocols through the access point and to limit the IP address ranges or specific IP addresses that may associate with the access point. The more stringent restrictions are especially useful in bridging applications when the major connection comes from a single, down-stream access point and all other connections can be refused.

The management interface also includes basic statistics on access point utilization, such as how much traffic of various types is flowing through the interfaces, which MAC addresses have associated with the access point, and how associated clients authenticated. This information will allow for reasonable management of a few access points.

If, on the other hand, you are dealing with an enterprise WLAN installation with scores or hundreds of access points, you’ll want to deploy Proxim’s Wireless LAN Manager software, which is designed for big WLAN deployments.

Managing it all

Wireless LAN Manager presents the same information provided by the AP-2000’s built-in management software but allows simultaneous access to data from a large number of access points. In addition, administrators can configure access points through the software and, most usefully, duplicate and download configurations from one access point to an unlimited number of others.

Proxim states that Wireless LAN Manager is compatible with Windows 2000 Pro or Server and Windows NT 4.0+ workstation or server. Believe them: The software is not compatible with Windows XP. Upon installation on a Dell PowerEdge 2600 running Windows 2000 Server (service pack 2), Wireless LAN Manager immediately recognized the Proxim APs installed on our network. Moving devices from the discovery window into named virtual groups is a matter of cut and paste. And you’re ready to go.

One of the more interesting statistics offered by the software is Client Load Distribution. This allows a manager to see the number of clients associated with up to 20 different access points and the traffic load generated on each one. In installations where access points have been deployed to offer reasonable bandwidth and response times to clients, this statistic provides a concise way of learning whether the distribution of access points is successful.

Certain functions performed by Wireless LAN Manager, such as device discovery, add some load to the network traffic; however, these functions can be scheduled to repeat at intervals that will disrupt the network as little as possible while still providing reasonable information for WLAN management. For major maintenance tasks, such as downloading new operating software, updating firmware, or rebooting access points, bulk sessions can be scheduled for times when interruption to network service will impact as few users as possible.

Taken as a whole, Wireless LAN Manager provides many useful fleet management tools for Proxim APs. It wraps the tools in a useable, easy-to-understand interface, and provides facilities for alerting managers to problems and creating audit trails for those issues. With all this, the build we tested did have one drawback — it seemed unstable. On two occasions, the software froze on the server (which was running no other applications) and closed. Both times, the software recovered on restarting and functioned well after that.

a + b = ComboCard

As for the wireless card itself, the Orinoco 802.11a/b ComboCard performed well in all our usage tests, providing seamless, reliable connections to both 802.11a and 802.11b access points through our office. Unlike Wireless LAN Manager, it is compatible with Windows XP. In our testing, we associated with access points from Cisco, Symbol, 3Com, Enterasys, and Proxim, with no discernable differences in performance or capabilities between any of the five.

Radio performance of the Orinoco card was similar to that of the Netgear WAB501 802.11a/b combo card, though the Orinoco card showed slightly better results in holding higher 802.11a signal strengths through obstacles.

The two drawbacks to the Orinoco card are present on every 802.11a/b combo card we’ve seen. First, the connection speed information associated with the card’s task-bar icon in Windows XP is inaccurate. When an 802.11a connection is present, the icon bubble always reports a 54 Mbps connection, even if the actual connection speed is 6 Mbps.

Second, the transition between 802.11a and 802.11b connections is far from smooth. If an 802.11a connection is removed, it can be minutes before the card finally gives up on 802.11a and switches to 802.11b, and vice versa. Until the transition happen more quickly, users will not get to see the full benefits of 802.11a/b combination systems.

Proxim’s Orinoco AP2000 is a solid, enterprise-class access point with tremendous flexibility, solid internal management software and a price considerably lower than the one set by Cisco for its competing product. The only possible fly in the ointment is Proxim’s separate Wireless LAN Manager software. Although definitely improved since our last review, it still froze on two occasions. We aren’t sure why it died, but any instability is worrisome in an enterprise management product.

If your deployment calls for dual-mode capabilities with easy access to future upgrades, then the AP-2000 is a great choice. If Proxim can make management software that matches the capabilities and performance of the access point, the result should be a true winner.