Aruba conquers challenge of Wi-Fi scalability

Two WLAN vendors brave our massive test plan.

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Clients roamed twice across all access points to show the performance benefit of caching a security parameter - the pairwise master key (PMK), which is generated during 802.1X authentication. Roaming should occur faster when a client roams back to an access point that has been authenticated, because there is no need to regenerate the PMK. To test this, we tracked roaming time before and after PMK caching. The difference was striking: Without PMK caching, the average roaming time was about 36 millisec, compared with an average roaming time of 16 millisec after caching. Clearly, enabling PMK caching is beneficial if it's supported, as it is with the Aruba gear.

Aruba passed our scalability tests with flying colors. Some of the results - especially in terms of throughput - were among the highest we've ever seen in Wi-Fi gear. Clearly, it's possible to scale Wi-Fi to enterprise levels.

Boatloads of thanks gratefully acknowledges the support of the vendors that made this project possible. Test- equipment vendor VeriWave ( supplied its WT-90 Wi-Fi test instruments, custom-developed a software test suite and assigned a large engineering team to support this project. Thanks also to APC, which supplied its NetShelter SX rack enclosures to house the test equipment and devices being tested.

Network World

Newman is president of Network Test, an independent testing and engineering services firm in Westlake Village, Calif. He can be reached at

NW Lab Alliance

Newman is also a member of the Network World Lab Alliance, a cooperative of the premier reviewers in the network industry, each bringing to bear years of practical experience on every review. For more Lab Alliance information, including what it takes to become a member, go to

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