By Andrew Garcia  |  Posted 2005-08-08 Print this article Print

Xirrus Inc.s innovative XS-3900 Wireless LAN Array packs many radios and a wireless switch into a single chassis, allowing administrators to easily deploy high-density, indoor wireless networks while saving dramatically on wireless rollout and installation costs.

Although the XS-3900 capably handled all the traffic eWEEK Labs threw at it in tests, the underlying management and wireless switching features could still use some polish.

The XS-3900s 16 IAPs (integrated access points), a single multichannel MAC (media access control) layer and specialized multisector antennas allow companies to use a single device to deploy a WLAN using all nonoverlapping channels in the 5GHz (IEEE 802.11a) and 2.4GHz (802.11b/g) spectrums, with a radio left over for wireless monitoring.

Click here to read about competing IEEE groups joining forces on a 802.11n standard. By default, the XS-3900 is configured to fully use both spectrums while avoiding interference from overlapping channels. Administrators can also optimize radio configuration for their environment with the click of a button.

eWEEK Labs tested the XS-3900 with Xirrus software load 1.1.3, which started shipping in June. The device carries a list price of $12,000. A $4,000 four-radio XS-3500 and an $8,000 eight-radio XS-3700 model are also available.

To test the XS-3900, we surrounded the device with 15 laptops, each configured with Cisco Systems Inc.s Linksys WPC55AG Dual-Band Wireless A+G Notebook Adapters. We configured the XS-3900 to permit only a single concurrent station to connect to each IAP; this allowed us to add each successive new client to an unused channel to test the XS-3900s maximum throughput capability.

We used Ixias IxChariot 6.0 Service Pack 1 to generate traffic load and measure throughput rates, configuring each wireless client to download data from an IBM dual-Opteron eServer 325 connected via the wired network to the XS-3900.

The XS-3900s individual IAP performance was fairly run-of-the-mill, topping out at 20M bps to 21M bps for each 802.11a and 802.11g radio. However, the XS-3900 easily accommodated full performance from all channels transmitting simultaneously, allowing us to transmit 240M bps of concurrent unencrypted wireless traffic with 15 IAPs active.

The arrays controller could not readily load balance wireless traffic from saturated channels to underused ones. In tests, we configured several clients to hammer away on a single channel, but the arrays controller wouldnt move any of the clients to the unused adjacent channel. The arrays controller currently relies on clients to make migration decisions, but improved load balancing functionality is coming soon, according to Xirrus representatives.

The XS-3900 supports the latest wireless security standards, including WPA (Wi-Fi Protected Access) and IEEE 802.11i, offering both AES (Advanced Encryption Standard)- and TKIP (Temporal Key Integrity Protocol)-based encryption with either RADIUS-based 802.1x or WPA-PSK (WPA Pre-shared Key)-based authentication. For those with legacy clients, WEP (Wired Equivalent Privacy) is also supported.

With the XS-3900, we could create as many as 16 distinct wireless networks and establish different security parameters and VLAN (virtual LAN) memberships for each. However, wed like to see improved granular controls that would allow us to configure different shared secrets on a per-network basis, rather than the current per-device setup, and offer improved capabilities to support WPA-PSK and WPA-RADIUS on separate networks, instead of requiring both on each.

We easily configured the XS-3900 to use our Funk Software Inc. Steel-Belted RADIUS server for authentication. The XS-3900 also offers an internal RADIUS server for smaller deployments, but the internal database works only with the PEAP (Protected Extensible Authentication Protocol) transport mechanism.

In the XS-3900, we dedicated a single IAP to wireless monitoring. Using the embedded omnidirectional antennas (the XS-3900 also features three coaxial ports to connect optional external antennas), the XS-3900 cycles through all 802.11a/g channels to identify unknown access points, but the XS-3900 does not offer much in the way of wireless intrusion prevention or attack recognition at this time. Xirrus engineers are working to integrate AirMagnet Inc.s AirMagnet Enterprise software into the array.

The XS-3900 includes a pair of Gigabit Ethernet ports for redundant connections to the wired backbone network and a 10/100M-bps Ethernet port for out-of-band management. The XS-3900 features a standard AC power connection, or companies can provide 48-volt DC power via a Category 5 Ethernet cable from the optional XP-3100 Remote DC Power System (priced starting at $2,000).

We managed the XS-3900 via the Web-based GUI and the command line, which is available via SSH (Secure Shell) or console cable. Although the Web interface was straightforward and easy to navigate, wed like to see Xirrus add a time-based session logout because a careless administrator can stay logged in to the console indefinitely—even if the array is rebooted.

Next page: Evaluation Shortlist: Related Products.

Andrew cut his teeth as a systems administrator at the University of California, learning the ins and outs of server migration, Windows desktop management, Unix and Novell administration. After a tour of duty as a team leader for PC Magazine's Labs, Andrew turned to system integration - providing network, server, and desktop consulting services for small businesses throughout the Bay Area. With eWEEK Labs since 2003, Andrew concentrates on wireless networking technologies while moonlighting with Microsoft Windows, mobile devices and management, and unified communications. He produces product reviews, technology analysis and opinion pieces for eWEEK.com, eWEEK magazine, and the Labs' Release Notes blog. Follow Andrew on Twitter at andrewrgarcia, or reach him by email at agarcia@eweek.com.

Submit a Comment

Loading Comments...
Manage your Newsletters: Login   Register My Newsletters

Rocket Fuel