I read over the NOVARUM findings and was wondering if there was
somewhere that had more specifics on the testing, as I find the
results potential enlightening. I'm curious about the airtime fairness
results, particularly with Aruba. There are two options: fair vs
preferred access, where preferred would actually cater more airtime to
higher-performing clients, such as 11n (vs 11a vs 11g vs 11b). This
statement makes it seem Aruba was configured for "preferred" instead
of "fair" perhaps: "while the Aruba AP consistently showed a marked
bias towards the 11n clients". Also, in terms of mixed voice/data
application, I'm curious about whether any QoS configuration was
performed, specifically for ensuring WMM was enabled and ensuring
queueing downstream voice on the controller.
Again, if anyone has a source for more details, I'd like to read them.
Thanks!
==========
Ryan Holland
Network Engineer, Wireless
CIO - Infrastructure
The Ohio State University
614-292-9906 [email protected]
On Jul 30, 2009, at 12:09 PM, Manoj Abeysekera wrote:
In my humble opinion I think both single-channel architecture and
multi-channel architecture purely depend on the location (RF
Environment). I've seen some solid test results from Meru, I also
know some people who has gone with Meru with better results than two
other giants, Dave Akin from CWNP program had also observed the (now
famous "NOVURUM") test results of Meru and would bet his mortgage on
it.
At the same time I agree with Bruce if you have a very complex RF
environment (and most of time you have to share this unlicensed
frequency) single-channel (Meru) is coming little short. Whereas
multi-channel architecture would give you more options and RRM
(Cisco -Interestingly no one mentioned Cisco) or ARM from Aruba will
let you with some easy maneuvering. Then again one could argue that
if it is broad/spread-spectrum interference, then no one can save
you.
So the point i am trying to make is, it all depend on your location.
If you are such a isolated edu with whole spectrum is at your
mercy, then Meru would do a wonderful job. However if you are in the
heart of a city center i would consider ARM to "steer" me clear.
As i have professed before success of a WLAN deployment depend on
two important things for most nonprofit edu's.
Location-based design (before and after choosing a vendor)(whether
for whole campus or for one building)
Per-unit price (so that you could come up with "your" own
requirement) (Uni's with disposable Income don't bother)
Then come the feature-set and everything in between...
Remember what we after is not "band-steering" or "channel-stacking".
We after decent and stable Wi-Fi signal for our user community.
my $.02
Manoj
--------------------------------------------
P. Manoj Abeysekera, CWNA
Network Engineer
American University
4200 Wisconsin Ave, NW
Washington DC. 20016
"Osborne, Bruce W. (NS)" <[email protected]>
Sent by: The EDUCAUSE Wireless Issues Constituent Group Listserv <[email protected]
>
07/30/2009 08:15 AM
Please respond to
The EDUCAUSE Wireless Issues Constituent Group Listserv
<[email protected]>
To
[email protected]
cc
Subject
Re: [WIRELESS-LAN] Single Channel vs Multi-Channel Architecture
Jason,
I wholeheartedly agree. We here at Liberty University spent a year
evaluating wireless & NAC solutions. We chose to move from Cisco
“fat” APs & Clean Access to Aruba’s wireless & ECS NAC solutions.
The real challenge is in dense environments. Meru’s “single channel”
becomes “channel stacking” aka multi-channel to provide additional
bandwidth. You then have the client roaming issues again. Also, you
cannot “steer” clients to load balance the clients across available
resources. Aruba’s ARM 2.0 has many options in this situation and
solves many of the issues that Meru’s architecture solves.
With a single channel architecture, you are “stuck” if some
interference appears in that RF range. The system may be able to
change to another channel, but that WOULD CAUDE *all* the clients to
roam. In a multi-channel architecture, only a small number of
clients would be affected.
There is obviously a reason why Meru is the _only_ vendor with
single channel. All the others (including the largest players) use a
multi-channel solution. If Meru’s solution is so great, you would
see others with single-channel too, even if they needed to license
technology from Meru.
Bruce Osborne
Liberty University
From: Jason Appah [mailto:[email protected]]
Sent: Wednesday, July 29, 2009 1:44 PM
Subject: Re: Single Channel vs Multi-Channel Architecture
I agree wholeheartedly, the Aruba ARM works quite nicely, recently
the neighboring hospital turned up its radios, and ARM switched us
out without missing a beat. We reviewed Merus’s devices and liked
the approach, but were less than wowed with the completeness of the
feature set.
In the end we choose Aruba for four reasons:
Price – pretty self explanatory
Performance/deployment - (this was identical in most and in many of
our use cases better than Meru)
Feature Set – Aruba has obviously spent many hours actually
listening to and implementing user centric changes, I don’t know of
a more feature rich wireless solution
Support – Aruba has in many occasions been proactive, where I have
posted a question to this forum and others to actually go out of
their way to contact me to help me fix a problem, in some instances
where the problem wasn’t even Aruba’s at all…
We haven’t looked back.
From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[email protected]
] On Behalf Of Ken Connell
Sent: Wednesday, July 29, 2009 9:15 AM
To: [email protected]
Subject: Re: [WIRELESS-LAN] Single Channel vs Multi-Channel
Architecture
I don't have much experience with a single channel deployment, but
without even getting into vendor preferences or specifics I can't
see how a single channel can gain any perfomance in such an
unpreditctable and dynamically changing environment as far as other
devices, and wireless networks that will come and go probably a
daily basis with little or no control.
The channel you decide on today, may not be the best suited channel
tomorrow, and if you then need to make a change at that point, then
you've jsut come full circle and are right back where you started.
In my opinion it just makes sense to go with an automated RF type
deployment (Aruba ARM for us) and be able to sleep at night ;)
Ken Connell
Intermediate Network Engineer
Computer & Communication Services
Ryerson University
350 Victoria St
RM AB50
Toronto, Ont
M5B 2K3
416-979-5000 x6709
From: Ryan Holland
Date: Wed, 29 Jul 2009 09:04:34 -0400
To: <[email protected]>
Subject: Re: [WIRELESS-LAN] Single Channel vs Multi-Channel
Architecture
...interesting thread...
When we were making our decision 3+ years ago, we discounted Meru
primarily on scalability information in their RFP response. So
unfortunately, we did not get a chance to bring them in for a demo.
I am still quite skeptical about a single-channel architecture but
believe I understand why it is promoted: to assist devices in
roaming by creating a seemingly single BSSID. However, once we see
more devices supporting standards such as 802.11k and 802.11r, such
efforts, to me, are negated. Again, however, I have not had the
opportunity to play with this gear, so [disclaimer].
We have been deploying Aruba for sometime and have learned a great
deal about their technology, so I will caution the trusting of
intelligent radio management solutions. Instead, I would suggest one
utilize this technology while maintaining a tight supervision of it.
Using Aruba with whom I am most experienced, their adaptive radio
management (ARM) is quite powerful, as it allows for dynamic
remodeling for channel and power based on the environment. This
means that as other building tenants bring in their own wireless
systems, our network can modify its channel configuration
accordingly. Also, in the event of an AP failure, adjacent APs will
likely perceive a lower aggregate signal strength of neighboring
APs, boost their power, and thus help alleviate the loss of coverage
from said failed AP.
The reason I cautioned earlier is that many administrators simply
"turn on ARM" and leave it. Doing so is assuming the defaults are
applicable for all environments, which I would argue is not true for
most educational institutions. Examples: the range of chosen
transmit power is likely too expansive; the noise threshold at which
an AP would change channels may be too low, especially for "research
areas" like Illinois mentioned; the target coverage index may be
too low for densely deployed installations or too high for sparsely
deployed installations. Aruba is great in that administrators can
configure different ARM profiles for all these different
circumstances and use them suitably. But again, to just turn it on
and expect it to "work" can lead to false assumptions.
I would also add that there are still a lot of those that state
static channel/power assignments is the best way to go. While I
would agree that is true assuming the environment is identical at
installation as it was during survey, it is incredibly likely that
the environment will change and therefore negate the initial survey.
Because our environments are largely unpredictable, I find a dynamic
solution to be preferable. Now, if we had complete control over RF
across campus, my opinion may be different.
(Oh, and because people seem to be concerned with these sorts of
numbers: ~5,000 APs, ~40 controllers).
==========
Ryan Holland
Network Engineer, Wireless
CIO - Infrastructure
The Ohio State University
614-292-9906 [email protected]
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