Aggressive Client Load Balancing

Information About Aggressive Client Load Balancing

The Aggressive Client Load Balancing feature allows lightweight access points to load balance wireless clients across access points.

When a wireless client attempts to associate to a lightweight access point, the associated response packets are sent to a client with an 802.11 response packet including status code 17. This code 17 indicates that the corresponding AP is busy. The AP does not respond with the response 'success' if the AP threshold is not met, and with code 17 (AP busy) if the AP utilization threshold is exceeded, and another less busy AP hears the client request.

For example, if the number of clients on AP1 is more than the number of clients on AP2 and the load-balancing window, then AP1 is considered to be busier than AP2. When a client attempts to associate to AP1, the client receives an 802.11 response packet with status code 17, indicating that the access point is busy, and the client attempts to associate to a different access point.

You can configure the controller to deny client associations up to 10 times (if a client attempts to associate 11 times, it will be allowed to associate on the 11th try). You can also enable or disable load balancing on a particular WLAN, which is useful if you want to disable load balancing for a select group of clients, such as time-sensitive voice clients.


Note

A voice client does not authenticate when delay is configured to more than 300 ms. To avoid this, configure a central-authentication, local-switching WLAN with Cisco Centralized Key Management (CCKM), configure a pagent router between an AP and WLC with a delay of 600 ms (300 ms UP and 300 ms DOWN), and try associating the voice client.


Note

For a FlexConnect AP, the association is locally handled. The load-balancing decisions are taken at the controller. A FlexConnect AP sends an initial response to the client before knowing the result of the calculations in the controller. Load-balancing does not take effect when the FlexConnect AP is in standalone mode.

A FlexConnect AP does not send (re)association response with status 17 for load balancing the way local-mode APs do; instead, it first sends (re)association with status 0 (success) and then deauth with reason 5.


Note

This feature is not supported on the APs joined on default-site-tag.

This feature is not supported on the APs across different named site-tags.

This feature is supported only on the APs within a named-site-tag.

Enabling Aggressive Client Load Balancing (GUI)

Procedure

Step 1

Choose Configuration > Wireless > WLANs > Wireless Networks.

Step 2

Select a WLAN to view the Edit WLAN window.

Step 3

Click Advanced tab.

Step 4

Select the Load Balance check box to enable the feature.

Step 5

Click Update & Apply to Device.

Configuring Aggressive Client Load Balancing (GUI)

Procedure

Step 1

Choose Configuration > Wireless > Advanced.

The Load Balancing window is displayed.

Step 2

In the Aggressive Load Balancing Window (clients) field, enter the number of clients for the aggressive load balancing client window.

Step 3

In the Aggressive Load Balancing Denial Count field, enter the load balancing denial count.

Step 4

Click Apply.

Configuring Aggressive Client Load Balancing (CLI)

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device# enable

Enters privileged EXEC mode.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

wlan wlan-name

Example:

Device(config)# wlan test-wlan

Specifies the WLAN name.

Step 4

shutdown

Example:

Device(config-wlan)# shutdown

Disables the WLAN.

Step 5

load-balance

Example:

Device(config-wlan)# load-balance

Configures a guest controller as mobility controller, in order to enable client load balance to a particular WLAN.

Configure the WLAN security settings as the WLAN requirements.

Step 6

no shutdown

Example:

Device(config-wlan)# no shutdown

Enables WLAN.

Step 7

end

Example:

Device(config)# end

Returns to privileged EXEC mode. Alternatively, you can also press Ctrl-Z to exit global configuration mode.

Step 8

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 9

ap dot11 { 24ghz| 5ghz} load-balancing denial denial-count

Example:

Device(config)# ap dot11 5ghz load-balancing denial 10

Configures the load balancing denial count.

Step 10

ap dot11 { 24ghz| 5ghz} load-balancing window number-of-clients

Example:

Device(config)# ap dot11 5ghz load-balancing window 10

Configures the number of clients for the aggressive load balancing client window.

Step 11

end

Example:

Device(config-wlan)# end

Returns to privileged EXEC mode.

Step 12

show running-config | section wlan-name

Example:

Device# show running-config | section test-wlan

Displays a filtered section of the current configuration.