I agree with Joel, 80-100 users per AP is a bit much on an AP. What's
the ratio of 2.4 GHz to 5 GHz? I'm not familiar with the 1240 (have a
couple but none of them work), do they have any smartRF built in (can
they "nudge" dual band clients to 5 GHz)?
--
Heath Barnhart, CCNA
Information Systems Services
Washburn University
Topeka, KS 66621
On 11/10/2011 11:30 AM, Coehoorn, Joel wrote:
Your problem is probably air time density.
The issue is that you only have 3 non-overlapping channels to work
with in the 2.4Ghz space, most users won't have 5Ghz-capable laptops,
each channel only supports about 25 clients from a practical
standpoint, each access point is likely only listening on one specific
channel, and you have up to 400 users trying to connect all at about
the same time. That's just not going to work. Things get better a
few minutes after a class starts because some students will just give
up, and most others will settle down to only use air time only in
short bursts, as they load and then pause to read pages.
The typical solution is turning down the transmit power, such that
signal for each access point does not leave it's own classroom, and
then add access points to each classroom such that you're listening on
more of the available channels within the rooms. The goal is to reduce
the cell size (and therefore number of clients) served by each access
point, and increase the available channels. You can do this by adding
access points, or by getting single access points with multiple
independent radios that are capable of using the additional channels
simultaneously.
Even here, you'll likely still have issues as many of the laptops will
not turn down power to their own radios and still clutter up the air
space. It would be like trying to listen to the professor if most
students in the classroom were also having conversations among each
other at their normal speaking volume.
As for distributing traffic, there are different load-balancing
options out there depending on your vendor. But even with generic
thick access points you'll see quite of bit of load balancing happens
naturally, without you having to do anything special so encourage it.
You ought to be able to just add the access points without needing to
do much of anything for load balancing.
Joel Coehoorn
IT Director
York College
402.363.5603
On Thu, Nov 10, 2011 at 11:09 AM, Ethan Sommer <[email protected]
<mailto:[email protected]>> wrote:
With almost any manufacturer you can set a max number of clients
per radio. You could set the max per radio to 25ish and put
(capacity of classroom/25) APs per classroom.
On 11/10/2011 10:54 AM, Luis Fernando Valverde wrote:
Hello,
we have four adjacent classrooms (two in front of two and 5
meters between each one) with capacity to 80-100 students each
one. Each classroom has its own Cisco Aironet 1240 AG Access
Point.
When all the students inside the classroom connect their
computers to the wireless network, response time behaves very
slowly for several minutes, until the traffic network stabilizes
and reaches a better performance. We have tested other AP
including Ruckus (802.11 b/g/n) and the problem remains.
We could install two AP by classroom, but we would need to
distribute the connections between each one. Does someone know a
solution without having to use different SSIDs to distribute
traffic among multiple access points? Does someone have any
suggestion to solve this issue, including other access point
manufacturer?
Any comment is welcome.
Thanks,
-----------------------------------------------------------------------------------
Luis Fernando Valverde
Director de Tecnología de Información y Comunicaciones
INCAE Business School
Tel: 506+ 24 37 23 38
www.incae.edu <http://www.incae.edu>
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--
Ethan Sommer
Associate Director of Core Services
Gustavus Technology Services
[email protected] <mailto:[email protected]>
507-933-7042 <tel:507-933-7042>
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**********
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