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Joanie Wexler looks at how enterprises can take advantage of wireless LANs and WANs.
For LANs to go "all wireless," they must achieve close technical parity with Ethernet. The wireless LAN industry appears hard at work to make it so.
The first segment of the LAN to break free of cables is the connection between client devices and wireless access points (AP) for obvious mobility reasons. From there, wireless mesh AP-to-AP connections promise enterprises some relief from the labor and expense of physically having to cable every AP to an Ethernet switch port.
Getting WLAN throughput to respectably compete with Ethernet in both these network segments is being addressed by the emerging IEEE 802.11n standard. A number of pre-standard enterprise-class products are available that support throughput well above 100Mbps.
Next on the list of Ethernet attributes for WLANs to match is high availability (HA). HA considerations extend from the radio-frequency (RF) access network all the way to the back-end controller network (in controller-based architectures) and authentication servers.
In the RF segment, most enterprise WLAN vendors have developed fairly sophisticated and automated capabilities for detecting interference and dynamically moving wireless devices to less cluttered channels to keep communications running. Most also balance traffic loads among APs to ensure connection success.
If an AP fails, depending on architecture, a nearby AP increases its power output to fill in the gap or will route around the failure to another AP. A number of vendors, too, have pushed key functions out to the AP so that if there is a controller failure, existing WLAN sessions keep on running.
Still, the RF client-to-AP network is prone to having “sticky” and “frisky” clients. Sticky clients cling to a given AP even when they should roam to one with a stronger signal. Frisky clients do the opposite, detecting multiple signals and ping-ponging back and forth among APs. Both conditions can drop or disrupt sessions. To stabilize the RF environment, the trend is to move WLAN-wide operational decisions out of client devices and into the network infrastructure. At least three vendors – Meru Networks, Extricom and, most recently, Aruba – are using controller-based decision making to help in the HA area.
Meru, for example, has been shipping (but has not yet officially announced) an RF capability called Proactive Spectrum Management (PSM). PSM centrally analyzes the RF environment, taking into account variables such as interference from other Wi-Fi networks and devices, and assigns a “goodness” value to each channel, explains Rachna Ahlawat, VP of strategic marketing. At any point in time, it ensures that all APs operating on a common channel in the company’s Virtual Cell single-channel architecture are tuned to the one with the highest score, she says.
Joanie Wexler is an independent networking technology writer/editor in Silicon Valley.
Comments (9)
PSM software versionBy Anonymous on October 27, 2008, 9:47 amWhich version of Meru software supports PSM?
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Moving from availability to satisfied customersBy Anonymous on October 27, 2008, 10:22 amWhile high service availability is the basic measure of service quality, it is far from sufficient. It is essential to ensure service quality from the end user to...
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What about MotorolaBy Anonymous on October 27, 2008, 11:05 amMotorola is key player in the "Wireless by Default, Wired by exception". With it's indoor meshing product consisting of a/b/g/n radio's coupled with the outdoor...
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Other VendorsBy Anonymous on October 27, 2008, 12:02 pmPer the last paragraph of this newsletter, please stay tuned until Wednesday's newsletter to read about Motorola and several other WLAN players. And remember...
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It is available in Meru System Director software Release 3...By Anonymous on October 27, 2008, 4:49 pmIt is available in Meru System Director software Release 3.6, according to the company. Joanie Wexler, author of Network World's Wireless newsletter
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REPLYBy Joanie Wexler - NWW Wireless Alert on October 27, 2008, 5:09 pmIt is available in Meru System Director software Release 3.6, according to the company.
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