Cisco Load Balance configuration
More detail explanations can be found a http://www.Cisco.com
Sometime referred to as advanced Load Balancing (Load balancing +). Is an enhancement to Aggressive load balancing, it allows you to configure load balancing per WLAN. Feature is disabled by default
Feature load balances wireless clients across Access point. Clients are only able to be load balanced across access points on the same WLC. Load balancing does not occur between access points on different controllers.
Load balancing only works at the association phase.
when a client tries to associate to a Cisco Lightweight Access point, association response packet is sent to the client with an 802.11 response packet including status code 17. The code 17 indicates that the AP is busy, so the client has to look for another AP to associate with.
The AP responds with association response bearing “success” if the AP threshold is not et, and with code 17(AP busy) I the AP utilization threshold is reached or exceed and another less busy AP heard the client request.
Problem can arise, if AP discarded or sends a status code 17 to client then client have to decide to ignore it or still use the same AP. Some client driver uses the same AP for connection once again but most of the other type of clients tries to find other AP for connection. So it depends on vendor drivers, as you cannot force them to accept the status code 17.
It is recommend not to enable this feature for the voice WLAN as it can cause roaming issues. For other WLANs, it should be enabled only after testing.
- Client Window size: the client size window and client n least loaded AP determine the load balance threshold value.
Before configuring the load balance intelligence, remember the formula. An AP is considered busy once it has a number of associated clients equal to the client windows size plus the number of clients on the least loaded AP in the area
Load-balancing threshold= client window size + number of clients on the least loaded AP
Example: 3 AP
AP1: 9 clients
AP2: 7 clients
AP3: 4 clients
As per last default settings on last screen shoot client window size is 5
As per formula, load balance threshold is =5+4=9
Means if any new client wants to join AP1 then client will get the status 17(busy) message or in other words this AP(AP1) is considered to be busy.
- Maximum Denial count: the maximum denial count parameter allows the user to configure the number of times the client associations will be rejected for a particular AP. The maximum denial count can have a value between 0 and 10
Figure 1. Client Load balancing global configuration windows
Figure 2. Client Load balancing configuration per WLAN
Figure 3 Client Load balancing configuration options
Figure 4. Client Load balancing window
Figure 5. Client Load balancing denial count
Figure 6. enabling Client Load balancing configuration
Figure 7. Disabling WLAN inference
then enable Client Load balancing by # Config plan load-balance allow 1
Figure 8. enable WLAN inference
Figure 9. Displaying Load balancing information
Figure 10. Displaying WLAN configuration information