Load Balancing
Enabling load balancing improves the WLAN performance by directing the wireless client load between the access points. Load balancing can be controlled from within the controller web interface to balance the number of clients per radio on adjacent APs.
Adjacent APs are determined by the controller at startup by measuring the Received Signal Strength Indicator (RSSI) during channel scans. After startup, the controller uses subsequent scans to update the list of adjacent APs periodically and when a new AP sends its first scan report. When an AP leaves, the controller immediately updates the list of adjacent APs and refreshes the client limits at each affected AP.
After the controller is aware of which APs are adjacent to each other, it begins to manage the client load by sending the configured client limits to the APs. These limits are soft values that can be exceeded in several scenarios, including:
- Client signal is weak and cannot support a link with another AP.
- Client signal is strong and belongs to this AP.
The APs maintain these configured client limits and enforce them after they reach the limits by withholding probe responses and authentication responses on any radio that has reached its limit.
To enable Load Balancing following are the considerations:
- The load balancing rules apply only to client devices; the AP always responds to another AP that is attempting to set up or maintain a mesh network.
- Load balancing does not disassociate clients already connected.
- Load balancing takes action before a client association request, reducing the chance of client misbehavior.
- Load balancing does not require any time-critical interaction between APs and the controller.
- Provides control of adjacent AP distance with safeguards against abandoning clients.
- Load balancing can be disabled on a per-WLAN basis. For instance, on a voice WLAN, load balancing may not be desired due to voice roaming considerations.
- Background scanning must be enabled on the WLAN for load balancing to work.
By default the Load Balancing is disabled, enable the feature by choosing the appropriate functionalities:
- Based on Client Count: Access points are set to a client threshold. If a client wants to associate with an AP whose current count is less, then the client is allowed to associate with the AP. If not then client evalutes the neighbouring APs.
- Based on Capacity: The capacity quantifies the maximum data transmitted over a network. Capacity determination is based on bandwidth, data rate and number of streams.
- Limit 2.4Ghz Clients to: By default, the functionality is disabled, click the toggle button to enable and set the percentage.
Steering Mode
Steering mode allows the access point to disable lower bandwidth from probing the client device. This allows the access point to respond to only one bandwidth. This helps in reducing congestion and take advantage of the higher bandwidth and improves user experience.
There are three modes in Steering Mode, choose the approriate mode by clicking on the functionality:
- Basic: Withold probe and authentication responses at connection time in heavily loaded band to balance clients to the other band.
- Proactive: Uses Basic functionality and actively rebalances clients through 802.11v BSS Transition Management (BTM).
- Strict: Uses Proactive functionality and forcefully rebalances clients through 802.11v BSS Transition Management (BTM).
Sticky Client Detection
There are instances where some client devices connects to an AP and stay connected to the same servicing AP, and does not change its association to the closer APs. These clients are referred as sticky clients.
These clients may experience degradation in service because of lower throughput resulting in poor user experience. The purpose of the sticky client detection is to identify these clients and assist in transition to a better AP.
By default, the sticky client steering is disabled, click the toggle button to enable and enter the following:
- SNR Threshold: Signal-to-Noise (SNR) ratio value evalutes signal based on the noise. Enter the value between 5db to 30db.
- NBRAP % Threshold: Network Based Application Recognition Protocol (NBRAP) is used to calculate a base SNR and compare it to the SNR received from a neighboring AP. The percentage range is between 10-40.