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New Member

Aggressive Load Balancing Not working

Hi all,

On our WLC we have enabled Aggressive Load Balancing for 20 clients. However, when monitoring this via WLC we are seeing more than 20 clients connecting to any one APs (25-35+ clients). All APs belong to the same group and are set to local. We have a mix of 1130, 1141 and 1230 APs. We don't have any VOIP devices.

Example of report via WLC.

Top APs By  Client Count  
AP Name Map Location a/n Clients b/g/n Clients Total Clients
AP-LIB-01Unassigned28432
AP-C5-01Unassigned25530
AP-C4-01Unassigned24428
AP-LIB-02Unassigned22224
AP-C7-01Unassigned12113

Any ideas on how I could troubleshoot this?

Regards,

Mark

5 REPLIES
Gold

Re: Aggressive Load Balancing Not working

This isn't surprising.  When a client starts to associate to the AP when aggressive load-balancing is enable the AP will reject the association with a reason code of 17 if there is a neighboring AP that is less loaded.  Code 17 is defined under the spec but is optional.  It tells the client to try assicating to the next AP in its roam candidate list.  Most client cards I've come accross don't support code 17 so they just keep trying to associate to the same AP.  After the third attempt the AP will let the client on regardless of how loaded it is.

New Member

Re: Aggressive Load Balancing Not working

"On our WLC we have enabled Aggressive Load Balancing for 20 clients. However, when monitoring this via WLC we are seeing more than 20 clients connecting to any one APs (25-35+ clients). All APs belong to the same group and are set to local. We have a mix of 1130, 1141 and 1230 APs. We don't have any VOIP devices."

According to the Cisco documentation, if you put in the number 20 for "widow", that's calculated into an algorythm.  I don't think that it necessarily means 20 clients, but the window is added to the number of clients and then calculated.

From their documentation "You can enter a value between 1 and 20 for the clients parameter. The load-balancing window becomes part of the algorithm that determines whether an access point is too heavily loaded to accept more client associations:

load-balancing window + client associations on AP with lightest load = load-balancing threshold"

So, I don't know if this helps, but I noticed while reading through their material.

-Blair

New Member

Re: Aggressive Load Balancing Not working

Hi everyone,

Thanks for the reply.

So in genernal how do WLC / WCS balance client connectivity between access points?

Mark

New Member

Re: Aggressive Load Balancing Not working

unfortunately, aggressive load balancing looks more dependent on the client wireless NIC. Its up to the client device to acknowledge the Reason Code 17 that the access point sends and to search for any other access point located nearby.

WCS supports Aggressive Load Balancing, however, all that the access point can do is send out the "Reason Code 17" but not block the connection itself. Cisco  WCS has the value "Maximum Denial Count", which I suspect is the number of times the AP will deny  client association once the maximum number is reached. But if the client association attempt crosses this  "Maximum Denial Count", the access point will allow association. the  " It might be good idea to look into the client Wireless NIC

New Member

Re: Aggressive Load Balancing Not working

Thanks Shankar!

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