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Leveraging new WLAN standards

802.11n was finally ratified in September, and other new WLAN standards are enabling developments in enterprise voice, multimedia WLAN admission control, and wireless network management. WLAN solution providers can leverage customer demand by learning about these advances and how they will meet customer needs -- both today and tomorrow. WLAN solution providers may also want to keep a watchful eye on emerging standards so that they can respond quickly to customer questions about them.

In this tip, solution providers can learn how to leverage new WLAN standards to:

Business investment in WLAN infrastructure has long been stymied by changes to underlying standards and resulting concerns over investment protection. While home and small business users jumped on early "pre-N" WLAN products to increase reach and reliability, enterprises largely resisted temptation until the Wi-Fi Alliance 802.11n draft 2 certification program was launched in mid-2007.

Since then, enterprise investment in 802.11n draft 2 hardware has been significant, representing more than one-fourth of enterprise APs shipped in 4Q08 (In-Stat). Nonetheless, some businesses held back, awaiting the final 802.11n standard (ratified September 2009). Some have also delayed broader business mobility rollouts pending Wi-Fi Alliance certification programs for enterprise voice, multimedia admission control, and network management. WLAN solution providers can leverage this pent-up demand by learning about these advances and how they will meet customer needs -- both today and tomorrow.

  Put customer 802.11n certification concerns to bed
As IEEE ratification approached, the Wi-Fi Alliance pored through the latest draft standard to reach this conclusion: The core capabilities tested for 802.11n draft 2 certification have not changed. As a result, products that are already draft 2-certified do not need to be retested to prove that they are final 802.11n-certified. In short, customers should now feel comfortable that new clients that are final 802.11n-certified will interoperate with existing APs that are draft 2-certified, and vice versa.

This does not mean, however, that no advances have occurred since draft 2. To avoid consumer confusion (and vendor complaint), the Wi-Fi Alliance has now augmented its 802.11n certification program to test four new final standard options:

Some existing products already support these previously untested options. Some new products never will. But any new 802.11n products that implement these options will now test them to achieve final certification. WLAN solution providers should help their customers understand these options, where they might be needed, and whether they are present or absent in already deployed draft 2 products.

For example, customers that use 802.11n at only 5 GHz need not worry about the new coexistence test, which proves that an AP using a 40 MHz channel at 2.4 GHz can downgrade to 20 MHz to avoid co-channel interference. Customers using high-throughput applications may want APs that have passed the new spatial stream test, which splits data into three streams, sent over three antennas, to reach up to 450 Mbps (vs. draft 2's max-tested 300 Mbps). RF-hostile buildings may benefit from products that support STBC, a technique that sends redundant data differently over two spatial streams to facilitate error recovery. Finally, WLANs with high-volume applications like video can benefit from aggregation, which bunches little frames into bigger frames to increase efficiency by reducing 802.11 overhead.

  Multimedia WLAN opportunities
Many WLAN solution providers are already familiar with the IEEE 802.11e Quality of Service (QoS) standard and the corresponding Wi-Fi Multimedia (WMM) and WMM Power Save certification programs. These airtime prioritization and battery-life-extension features have little impact on best-effort data WLANs but are widely considered essential for multimedia WLANs -- especially those that include VoIP.

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To better address the unique challenges posed by wireless VoIP, the Wi-Fi Alliance further established an optional Voice-Personal certification program that tests voice application performance under real-life (voice plus data traffic) conditions found in typical home and small office WLANs. To become Voice-Personal-certified, a client or AP that has already passed WMM and WMM Power Save tests must demonstrate that it can also satisfy minimum requirements for packet loss, latency and jitter.

These standards and certifications are a good start, but they do not go far enough to ensure call quality in a typical enterprise WLAN. Gun-shy businesses that have conducted small wireless VoIP pilots with disappointing results need reassurance before they make more significant multimedia WLAN investments. To supply this confidence boost, the Wi-Fi Alliance is developing two more optional certification programs: WMM-Admission Control and Voice-Enterprise.

With WMM, customers can prioritize voice traffic above video, and video above best-effort data. However, when APs become overloaded, there just isn't enough priority airtime to go around. WMM-Admission Control can prevent this situation by effectively reserving resources to make sure that an AP can handle a specified number of calls. Voice-Enterprise will test products that pass WMM-Admission Control tests to verify acceptable voice application performance under typical enterprise WLAN conditions, including dozens of simultaneous calls and fast roaming between APs.

Solution providers can take advantage of these new programs to stimulate multimedia (especially voice) WLAN sales and support contracts. Customers that remain unconvinced about converged WLAN performance and scalability may need to be educated about existing and future WMM and voice certification programs. Providers that understand these can better help customers compare products, map them to business needs, and set realistic near-term and long-term expectations.

  Master wireless network management challenges
802.11 enjoyed quick success in the residential market because APs and clients can do what they do remarkably well with little or no supervision. However, the same RF and MAC layer configurations that work well in a lightly loaded home or small office WLAN can prove completely unacceptable in a large, heavily loaded enterprise WLAN.

Most enterprises have now migrated away from autonomous APs to centrally managed WLAN infrastructures that give administrators better insight into overall network operation and tools that can respond automatically to errors and outages. While network-side innovations like dynamic frequency selection, auto-transmit power adjustment and AP failover make a huge difference, they still do not address a big piece of the problem: diverse and largely autonomous 802.11 clients.

This is the turf that will be addressed by the IEEE 802.11v Wireless Network Management standard. Still under development, this standard will eventually serve as the foundation for a new Wi-Fi Alliance Wireless Network Management optional certification program. Capabilities that may be included in this program include more advanced client-side power save and time calibration features, and tools that enable interoperable client troubleshooting, diagnostics, reporting, and locationing in multi-vendor WLANs.

The wireless network management arena is rich in opportunities for WLAN solution providers. In the near term, providers can help their customers identify better network-side management tools and processes. Some tools will be supplied by enterprise WLAN vendors, while others may require integration of third-party products like wireless intrusion prevention and service assurance systems. In the absence of an interoperable standard like 802.11v, customers that require more control over clients may rely on proprietary station management capabilities. Providers can help customers understand the benefits and limitations of related programs like Cisco Compatible Extensions (CCX). Finally, providers can add value by offering multi-vendor WLAN management platforms like WaveLink Avalanche or the AirWave Management Platform.

  Look to the future of WLAN standards
Despite the success and relative maturity of today's WLAN technologies, wireless standards will continue to evolve, and new standards will continue to tackle unsolved problems. For example, 802.11s will someday specify an interoperable protocol for establishing wireless mesh networks (readily available today in proprietary form). 802.11aa will specify enhancements for robust audio-video stream transport to support consumer/enterprise multimedia applications. Someday, 802.11ad may further increase maximum WLAN data rates up to 1 Gbps.

While these innovations may prove useful to many enterprises, none of them is critical enough to forestall moving ahead with broader enterprise WLAN deployment today. In the meantime, WLAN solution providers may want to keep a watchful eye on emerging standards so that they can respond quickly to customer questions about them. One of the best ways to identify new WLAN standards that are actually being implemented is to monitor certification programs announced by the Wi-Fi Alliance.

 Lisa Phifer is president of Core Competence Inc., a consulting firm specializing in network security and management technology. For nearly 20 years, she has been involved in the design, implementation and evaluation of data communications, internetworking, security and network management products.

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