Hi Philippe,
We'd be very interested, as others are I'm sure to hear what you
find out from your testing.
--
Don Wright
Brown University
CIS - NTG
On 4/1/08 10:53 AM, "Philippe Hanset" <[EMAIL PROTECTED]> wrote:
> Dave,
>
> At Univ of TN, our intention is to deploy 802.11n capable APs where our
> 802.11b/g AP are located right now, use one radio at 2.4 GHz (b/g only,
> no n) the second radio at 5 GHz (n and a).
> This should provide a decent access for b/g users and a fast lane for n
> users.
> I'm not sure that best effort on b/g will be good enough when you consider
> devices like Iphones or future Voice over WiFi devices.
>
> One aspect of this kind of approach will be the performance of coverage
> algorithms. n has such a wierd shape compared to b/g or a...I'm a little
> suspicious as how vendors will deal with n's behavior!
>
> As a side note:
> We are testing in our info-commons (the worse enviroment you can
> think of...tons of users and tons of APs) 802.11n APs from Aruba
> and Meru (we have just replaced locations of our existing Proxim APs
> with the test APs, and those n APs are surrounded by legacy Proxim APs as
> well)
> One week with Aruba, one week with Meru. We might test Cisco...TBD.
> Our main issue is to get enough people with 802.11n adapters, so we
> loaded our loaners laptop (30+...very successfull program BTW) with
> external 802.11n adapters (USB 2.0, Linksys).
>
>
> Philippe
>
>
>> Although the issue of co-channel interference is an important one, I think
>> it may be reasonable to assert that its importance will be reduced with the
>> adoption of 5 GHz 802.11n. With over 20 non-overlapping channels, I believe
>> it will be possible to design high-density, micro-cellular WLANs that do not
>> suffer from performance degradation as a resulting of co-channel
>> interference. Over time, I believe 2.4 GHz will be thought of as a
>> best-effort legacy technology for most enterprises. I'd be curious how
>> others are viewing this.
>>
>> dm
>>
>> -----Original Message-----
>> From: The EDUCAUSE Wireless Issues Constituent Group Listserv
>> [mailto:[EMAIL PROTECTED] On Behalf Of Charles Spurgeon
>> Sent: Monday, March 31, 2008 4:31 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/.
>>
>
> **********
> 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/.
