Catering for increase in wifi users?

Unanswered Question
Jun 18th, 2008


The volume of wifi users within my organisation is set to increase by approximately 50% in the coming months. We are currently using Cisco Aironet 1200s which are providing a strong /good quality signal for all users. I need to know what is best way to cater for this increased load and still maintain the same level of wifi service.

I have the budget to buy more access points but will the load distribution be handled automatically?

Any advice you can give would be greatly appreciated,


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Overall Rating: 4.3 (5 ratings)
Scott Fella Wed, 06/18/2008 - 15:14

Depending on your applications, it is recommended to have around 20-30 users per ap. Again, it depends on your applications. As long as you have coverage with your current implementation, then just check the amount of users per ap and double that. Then if you go past your recommended figure, adding an ap will have to happen.

paulie007 Fri, 06/20/2008 - 06:22

Thanks for your reply.

So if I have to 2 APs for say 50 users. How will the APs handle the load distribution?

Or are wireless cards smart enough to connect to the least busy AP?

jeromehenry_2 Fri, 06/20/2008 - 07:41

Well, depends on your settings.

If your clients are data clients, and enterprise class type of cards, there is a feature called "aggressive load balancing" that precisely helps solving this kind of issue (On the controller, go to Controller > General).

The data client itself is usually not smart enough to solve the issue alone, its main preoccupation is "Is my SSID available on any AP? If it is so, which AP provides the best RSSI/SNR?" regardless of the load. Aggressive load balancing looks at the problem from the infrastructure standpoint and tries to load balance... not perfect, but better than nothing.

If your clients are voice clients, and CCX (Cisco 7921s for example), they also will look at the QBSS information element, that will give them the load on each AP, and they will definitely use this information to pick up the best AP based on the RSSI and the load... for voice clients, aggressive load balancing is disabled, and QBSS is used.

Hope it helps


pirateoftheairwaves Tue, 06/24/2008 - 20:53

hello, mr. jerome!!

i've over 300 laps in one of our projects. the issue is, some clients do not associate to the ap that is near to it. most of the time it goes to the further ap, like if the client is on the 2nd floor, it will associate to the ap on the 3rd or 4th floor, or the ap that is 4 rooms away. and the signal is really low. about 2-1 bar in the windows client card status. if i shutdown the ap that the client associates to, it will just go to another ap other than the ap near to it. if i shutdown all the ap it hops to, it will finally assoc with the ap near to it and the signal is excellent. i've verified the channel and power levels and they are proper configured not to overlap.

does disabling the aggressive load balancing help this issue? do the ap's need to be restarted after toggling this feature?


sorvarit Wed, 06/25/2008 - 00:36

Had the same problems with laptops associating to the less obvious accesspoints.

Could sit 3m from an AP, but my laptop would rather connect to another on the roof for outdoor access. It was just getting som sidelobe signals and stuck to that.

This wa WinXP with an Intel WiFi card. Upgrading the drivers solved that problem.

Scott Fella Wed, 06/25/2008 - 03:45

You don't happen to have the Cisco a/b/g cards in these. I have had issues in hospital settings with these cards too many times. These cards hold onto ap's until they actually loose connection to the ap it is associated to. What you can try is to disable the lower data rates you don't use. If you need to support B users, but don't have any need to support legacy devices that require 1mbps or 2mbps, then you have no choice but to leave the setting as is. Disabling aggressive load balancing might help if the area users are in is congested and some devices associate to other ap's. You can make the changes, but when you hit allpy, it will tell you if you if users will get dissconnected or not. You shouldn't have to restart the ap.

Like the other member mentioned, update your drivers..... helps most of the time.

dennischolmes Wed, 06/25/2008 - 04:37

Increase the roaming aggressiveness on your client devices. Roaming is a function of the client device and not a function of the infrastructure. You can do some things to increase the speed of the roam on a controller but that is really a bandaid approach. If you enable aggressive load balancing you will have issues with VoIP over Wireless. Try disabling 1,2, and in some cases 5.5 beacons, increase the roaming agressiveness on the client to solve your problem.

pirateoftheairwaves Wed, 06/25/2008 - 18:13

yep, got that point where it is the resp of the client to which ap it will assoc to. our proj is a transition from auto to lwapp. so comparing the two modes, RF with auto seems to be stabler. client seem to always choose to talk to ap that has a stronger signal. and when roaming, right away it will dissac from the old ap and join the next ap with better signal. with lwapp, a number of clients, even at power on, joins to a further ap and not the one near to them. even after they've been removed or disabled for some time on the wlc, it will just re-join the further ap.

should there be any diff bet auto and lwapp when it comes to roaming and rf behavior?

i will to check also the drivers of the clients.

thanks for all your inputs!!!

Scott Fella Wed, 06/25/2008 - 18:16

In my experience no. Just check the driver on one of the devices that has been giving you problems and makes changes little by little and make sure you document the changes.


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