Yet another architecture (sectorized multi-AP array). This is comparing apples and oranges (except we don't know the variety of traditional apple Tolly is comparing Xirrus to in the study).
I think the problem is all these vendors live in Silicon Valley flatland and don't consider the effect of high density in three dimensions. The Novarum test appeared to be an out-of-the-box comparison (no tweaks). I think it would be relatively straightforward for a 3-story building to be surveyed and tested with each vendors architecture and have an independent performance analysis conducted after its been tuned to each vendors satisfaction. But who's going to pay for it? In the tests you see conducted by the industry trade magazines, one or several of the vendors always decline to participate (not confidence-inspiring). Pay attention to who doesn't. Its an issue unique to wireless since it's the only medium that feeds upon itself, and is context (implementer, building) dependent. What we need to know are the assumed parameters for deployment of each vendor's architectures. If the "all defaults" (all proprietary automated features) bet is off, then we deserve to know exactly what each vendor is doing behind the scenes, especially those that do not follow the spirit of the standards (SCA). If they tell you "it depends," then you need to know everything the product does, and get recommendations for how to support all measure of services (voice, video, data, location) and the hazards each have on the other. -----Original Message----- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Chad Frisby Sent: Monday, March 31, 2008 4:41 PM To: [email protected] Subject: Re: [WIRELESS-LAN] Aruba's SCA vs. MCA whitepaper [was: Open Wireless in Higher Ed] Wireless Density of users and co-channel interference has already been solved. Micro cell or channel blanket architectures do not. Independent 3rd party test-results below by Tolly Group. http://www.tolly.com/DocDetail.aspx?DocNumber=206152 http://www.tolly.com/DocDetail.aspx?DocNumber=207181 Chad Frisby 303.406.3222 -----Original Message----- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Charles Spurgeon Sent: Monday, March 31, 2008 2:31 PM To: [email protected] Subject: Re: [WIRELESS-LAN] Aruba's SCA vs. MCA whitepaper [was: Open Wireless in Higher Ed] On Wed, Mar 26, 2008 at 10:31:50PM -0500, Frank Bulk - iNAME wrote: > I wish it was easier to evaluate the performance (not only aggregrate > throughput, but also QoS) of the MCA and SCA products in various scenarios > and density and usage, but unfortunately examining the impact of co-channel > interference on a large scale in variety of building types and architectures > with lots of APs and clients with realistic traffic patterns (in terms of > type and longitudinally over time) is not currently possible with the tools > available. I think we would learn that there certain scenarios where one > performs generally better over another. I, for one, would like to see more vendors step up and do the kind of testing of co-channel interference issues that was described in the recent Novarum whitepaper: http://www.novarum.com/documents/WLANScaleTesting.pdf As a user of typical multi-channel equipment, I'm not focussed on the SCA versus MCA debate. Instead, I would very much like to see more real-world test results on how the typical multiple APs on multiple channels (MCA) approach works at scale and under traffic loads. I think it's very interesting that the author of the Novarum whitepaper is also one of the developers of the 802.11 MAC, and that he states that he was "surprised at how easily we could drive these systems to unstable behavior." I've heard complaints from the vendors whose gear was used in the Novarum test. But I haven't seen any third-party tests commissioned by those vendors to replicate the tests and show where the problems were in the Novarum tests. I would be much more impressed by actual third-party test results based on a significant scale layout like the one used in the Novarum tests, rather than hearing complaints about the how the test was unfair since it was done under the auspices of Meru. The problems of co-channel interference and wireless channel meltdown under load are too important to be left to the marketing departments of the wireless vendors. On our campus the community has been adopting wireless networking at extremely high rates, and this technology has become much too important to allow it to be supported this poorly. Isn't it long past time for more real-world scale testing like the Novarum tests to be done to investigate the issues with CCI and channel meltdown under load in 802.11b/g systems and to develop some approaches for identifying and dealing with those issues? -Charles Charles E. Spurgeon / UTnet UT Austin ITS / Networking [EMAIL PROTECTED] / 512.475.9265 ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. The information transmitted in this electronic communication is intended only for the person or entity to whom it is addressed and may contain confidential and/or privileged material. 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