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gadget — Episode 099 – The Future of Wi-Fi from Xirrus
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Xirrus is a California-based manufacturer of unique, upper-echelon, enterprise-class, high-performance Wi-Fi Arrays that promise to provide “Switching Without Wires.” Looking like a flying saucer from the 1960’s, each of these units is actually a collection of multiple Access Points in a single, easy-to-deploy/simple to manage package.
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The Xirrus line includes the 4-radio XS4, the 8-radio XS8, and the monster 16-radio XS16. While the units may differ in their radio count, they share the same shape and operating system. The back of the XS4 has 48 and 12 volt ports for power, a Kensington lock port, a console port for serial access, and a single Gigabit Ethernet port. The XS8 and 16 up the functionality by adding an Ethernet port for out-of-band management, a second Gigabit Ethernet port and an internal power supply.
Though the Xirrus arrays can’t use standard Power over Ethernet, Xirrus does offer a variety of midspan power injectors so that the arrays can be mounted in an area and orientation that optimizes Wi-Fi coverage, even if it isn’t close to a electrical outlet. The secret sauce of Xirrus’ Wi-Fi solution isn’t just in the number of radios in each unit, but in how they are utilized. In a traditional enterprise-class Wi-Fi setup you have a group of APs that are connected to a central controller. You have to wire and mount each access point and because the RF energy emitted by each radio is Omni directional, you end up with APs stepping on one another, filling the air with noise, and generally crashing and burning once the Wi-Fi network becomes congested. Xirrus has taken a different path by combining the controller and the radios into a single unit. Not only does this decrease your deployment time by reducing the network and power runs that have to be made, but it also allows them to engineer exactly HOW those radios will interact with one another. Opening the array will reveal a series of radios and antennas that are clustered around a powerful central controller. Part of the Xirrus magic comes from the fact that they are currently the ONLY commercially available Wi-Fi system that divides the 360 degrees around an AP into several slices that can each be served by a different set of radios and antennas. What enables this “spatial division of Wi-Fi” is the fact that the radios and antennas sit within a specially designed “RF reflector” that that works something like the reflector in a flashlight, shaping the “Wi-Fi beam” into something that can be precisely targeted. This vastly increases the effective bandwidth capacity of a given AP and the effective speed to individual clients because your Access Points are not interfering with one another. It also increases range to twice that of a typical Access Point. This arrangement means that the XS16 can get up to 864Mbps of aggregate throughput. The XS8 tops out at 432 Mbps and the XS4 at 216. |
The controller itself is quite robust, with enough power to drive all the radios, the OS, the security software and the interface with plenty of headroom for future improvements. It sports a 2.1Gbps wireless switch, 512MB to 1GB of memory, a compact flash card containing the OS and, on the XS8 or 16, a PCI-X slot for future functionality. Xirrus uses a PowerPC CPU that gives the unit the ability to maintain full line-rate encryption.
The radios and antennas are contained on modules that are connected to the controller via an interface at the edge of each card. This means that they can be can be removed for easy servicing and upgrade. Simply sliding in a new blade will let you take advantage of 802.11n or any advanced in radio or antenna technology.
Xirrus has also included TNC antenna connectors that allow you to add coverage to wireless trouble spots, areas into which an array just can’t penetrate and in which it isn’t economical or desirable to add another Xirrus array.
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You have several ways to access the Array. You can use the console port for serial access, the dedicated out-of-band Ethernet management port on the XS8 and 16, or you can log in via an encrypted web interface. It also supports SNMP management, SSH and telnet. For large enterprise-class deployments Xirrus offers a custom MIB file to interface many arrays with their network management software. However, no matter how you log in, you’ll soon see that Xirrus’ hardware magic is backed up by some pretty serious software firepower.
Though the sheer number of services and configurations available through the menus might be daunting at first, it’s necessary to give users what they need from an enterprise-class wireless solution. You have at-a-glance access to pretty much every important metric from array status to network settings, connected clients and your VLAN configurations. Security-wise, Xirrus’ arrays have pretty much every security feature that you might want to implement on your network. They support WEP, WPA, WPA2. You can use open, pre-shared key, 802.1x, EAP, PEAP, and Captive Portal authentication. It includes an integrated stateful packet inspecting firewall. However, the more impressive security feature has to be the integrated Intrusion Prevention and Detection system. All of Xirrus’ products include a dedicated Wi-Fi Threat Sensor and spectrum analyzer with a 2dB omni-directional antenna. This hardware give you the ability to detect and block rogue Access Points, locate Wireless bottlenecks, map your Wi-Fi environment, look for interference and otherwise troubleshoot your wireless network without needing to buy an additional, and quite expensive Wi-Fi diagnostic tool like Airmagnet’s sensors. This Threat Sensor and Spectrum Analyzer also give you the unique ability to configure your wireless network with a before-unheard-of amount of information at your fingertips. The Xirrus arrays can break down each of the available channels by noise, congestion, error rate and a handful of other important factors. This will allow you to decide how best to configure your array so that it can perform as well as possible. Xirrus has included the ability to create up to 16 unique SSIDs for each array. This is tied together with the option of managing the availability of each SSID, bandwidth caps and security policy: meaning that not only can you have the array automatically allow and disallow access to certain groups or users depending on the time and day of the week, but you can also throttle them to an acceptable level of traffic. |
One of our favorite features is the integrated support for Spectralink’s Voice Priority protocol, a way to control Quality of Service for wireless Voice over IP handsets. Combined with the integrated DHCP server, the unique RF properties of the array, and the engineered redundancy of the Xirrus units, this means that these arrays could become the perfect companion for your wireless VOIP system.
