How to use Over the Air QoS in WLC 2106

Unanswered Question
Mar 28th, 2008

Hi all,

My company is using a WLC2106 with 4 APs directly connected to the port 4 - 8. With port one to management/data VLAN. Two SSIDs "Manager" and "Staff" using WPA + TKIP were created and both bridged to the management interface (assigned to port 1 untagged) of WLC. WLC port 1 is connected to C2950 FE port. Our network do not have any QoS.

I've changed the Maximum RF usage per AP to 10% in bronze and 10 for the queue length while keeping 100% and 50 for Max RF and queue length unchanged for silver profile in hope that Staff SSID will not use more than 10% of the RF channel (i.e. ~5Mbps) per AP

I tested the settings with four notebooks with staff:manager proportion 1:3 and 3:1 with only one AP on. However, none of which gives the expected result -- Staff share at most 10% (~5Mbps) of RF channel while manager share the remaining

It would be grateful if you could tell me if this can be achieved by solely Over the Air QoS of the WLC under our network? If not, how can be achieve this by modifying / adding additional gears.


I have this problem too.
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Scott Fella Sat, 03/29/2008 - 10:29

You need to have QoS running on your infrastructure to really see the difference if any. When the traffic starts degrading because of bandwidth limitations, then QoS will be used. The AP will not perform QoS over the air to limit bandwidth to certain users or SSID's.

Scott Fella Mon, 03/31/2008 - 10:47

I did find this, but doesn't explain much.

Q. What is meant by Over the Air QoS on a controller?

A. Over the Air QoS is a QoS parameter defined in a controller. It varies based on the user class.

In a Cisco Unified Wireless Networking environment, users on a wireless LAN can be categorized and assigned to any of these QoS profiles:





These profiles can be found under the Controller > QoS profiles page.

For each of these profiles, Cisco has the configurable Over the Air QoS parameter, which is found under the edit page of each QoS profile. This Over the Air QoS specifies two different settings for the particular class of user (QoS profile):

Maximum radio frequency (RF) usage (per access point [AP])-This is a maximum percentage of air bandwidth given to a user class. For example, if you have a network where the guest QoS profile has the max bw limitation for bronze set to 10% even if a single bronze user is using the AP, it can never receive more than 10% of the total available bandwidth.

Queue Depth-This is the depth of the queue for the particular class. It causes packets greater than the value to be dropped at the AP.

Note: Only the 1000 series supports the maximum RF usage setting.

George Stefanick Tue, 04/01/2008 - 02:33

I would agree with Fella. QoS needs to be throughput your wired and wireless to take advantage of QoS. Today QoS is almost always used in VoIP solutions where you need to lessen jitter and other delays that maybe caused by traffic congestion.

And to be honest, it sounds more to me as well you want to throttle /rate limit groups of users. QoS wont help with that... At a cost you can rate limit user by purchasing an appliance to do so ...

alenwong1 Fri, 04/04/2008 - 08:30

gstefanick, I'd preferred to throttle the throughput of one group of users when another group of people is using the APs..

Eventually I've solved the problem with Over-the-air QoS by assigning WLANs to bronze and silver priority, with WMM totally turned off.

With WMM enabled, devices joined to the WLAN of higher priority do not really get the traffic priortized. With WMM disabled, the feature works as expected by giving more bandwidth to devices in the silver WLAN overall.

4.2.61 to 4.2.112 shows the same behaviour as mentioned, and these can't be found on the documentation...

Scott Fella Sat, 04/05/2008 - 07:56


There are alot of things you will not find in the documentation. That is why this forum is so helpfull. If no one has ran into the issue here, I know TAC always has an answer or a workaround at times...


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