CISCO 9800 Series Catalyst Wireless Controller AP Load Balancing User Guide

RF based Automatic AP Load Balancing

Information about RF based Automatic AP Load Balancing

The RF based Automatic AP Load Balancing feature improves upon the existing Site Tag-Based Load Balancing feature, where the APs are load balanced by assigning them to wireless network control deamons (WNCD) based on site tags. If the APs in a named site tag are beyond the capacity of a WNCd, it may lead to uneven distribution of APs across the WNCd instances, resulting in high memory and CPU issues. Though the number of APs in a site tag can be limited to 1000 by using the load command, it may still lead to uneven distribution of APs if the AP load limit is not correctly configured. In some instances, all the APs belonging to a site tag may not be colocated as well.
The RF based Automatic AP Load Balancing feature uses Radio Resource Management (RRM) neighbor report-based AP grouping and load-balancing across WNCd instances.
When this feature is enabled, it forms AP clusters based on the RSSI received from AP neighbor reports. These clusters or neighborhoods are further split into sub-neighborhoods and smaller areas. The resulting groups of APs are then distributed evenly across the WNCd processes. The AP load balancing takes effect only after a controller reboot or through an AP CAPWAP reset triggered by the ap neighborhood load-balance apply command. When the RF based Automatic AP Load Balancing feature is active, it overrides other site tag-based load balancing.

Supported Platforms

• Cisco Catalyst 9800-80 Wireless Controller
• Cisco Catalyst 9800-40 Wireless Controller
• Cisco Catalyst 9800 Wireless Controller for Cloud
• Catalyst 9800 Embedded Wireless Controller for a Cisco switch

Prerequisites for RF based Automatic AP Load Balancing
Ensure that you run the feature on a stable network, where the APs are fully deployed and are given enough time to discover all the RF neighbors.

Restrictions for RF based Automatic AP Load Balancing

• You cannot use the same calendar profile for AP neighborhood policy or AP profile.
• This feature is supported only on APs in local and flex mode.
• You cannot run the feature when the overall load on the system is high.
• You cannot use the output of the show wireless load-balance tag affinity command when the RF based
  Automatic AP Load Balancing feature is enabled.

Use Cases for RF based Automatic AP Load Balancing

1. This feature allows using a single site tag for all the deployed APs.
2. This feature provides better load balancing of the APs across WNCd instances when more number of APs are attached to a named-site tag than the available capacity of the WNCds in the controller.
3. This feature is suitable for large number of client intra-WNCd roaming scenarios. For example, if a controller is configured in a campus to manage APs of two separate buildings, then all the APs of that building are assigned to a single WNCd rather than allocating them to separate WNCds.

Guidelines for RF based Automatic AP Load Balancing

• For a new deployment, use the site tags and follow the current site tag recommendations to evenly distribute the APs, or use the site tag load command to automatically distribute the APs. Using site tags, you can ensure that all the APs of the same site tag goes to the same WNCd, which helps in troubleshooting and intra-WNCd roaming.
• If you are unable to use a site tag because you cannot group APs, or do not want to spend time designing site tags, use the default site tag or any named site tag and turn on the RF based Automatic AP Load Balancing feature.
• In an existing deployment, if you have high CPU issues because of an unbalanced system, use the auto RRM load balance system instead of redesigning the site tags.
• In an existing deployment, if you do not have any CPU load issues despite having an unbalanced system, do not change anything.

Configuring RF based Automatic AP Load Balancing

Before you begin
There are two phases of the RF based load-balancing algorithm enablement:

1. Running the algorithm: The RF based Automatic AP Load Balancing feature run can be scheduled based on calendar profile start time expiry using ap neighborhood calendar-profile command, or on-demand start of the algorithm using the ap neighborhood load-balance start command. Calendar profile start timer can be scheduled daily, weekly, or monthly.
2. Applying the algorithm: The RF based Automatic AP Load Balancing feature can be applied by controller reload or by using the ap neighborhood load-balance apply command when the wireless load-balance ap method rf configuration is enabled.

Procedure

| Command or Action| Purpose
---|---|---
Step 1| configure terminal
Example:
Device# configure terminal| Enters global configuration mode.
Step 2| ap neighborhood calendar-profile calendar-profile
Example:
Device(config)# ap neighborhood
calendar-profile ap-calendar-profile| Configures an AP neighborhood calendar profile.
Note
After the calendar profile is set, it is optional to run Step 4.
However, if you want to immeditely perform a load balance, run Step 4.
Step 3| exit
Example:
Device(config)# exit| Returns to privileged EXEC mode.
Step 4| ap neighborhood load-balance start
Example:
Device# ap neighborhood load-balance start| (Optional) Starts AP neighborhood load-balance algorithm calculation and WNCd allocation.
Step 5| configure terminal
Example:
Device# configure terminal| Enters global configuration mode.
Step 6| wireless load-balance ap method rf
Example:
Device(config)# wireless load-balance ap
method rf| Configures RF-based AP load balancing.
Step 7| exit
Example:
Device(config)# exit| Returns to privileged EXEC mode.
Step 8| ap neighborhood load-balance apply
Example:
Device# ap neighborhood load balance apply| Runs on-demand RRM-based AP load balancing.
This command rebalances the APs using CAPWAP reset. If an AP is already in the correct WNCd instance, then it will not be  CAPWAP reset. This command cannot be executed if the RRM-based AP load balancing algorithm is running, or algorithm results are not available.

Disabling RF based Automatic AP Load Balancing

Before you begin
RF based Automatic AP Load Balancing feature is disabled by default. The APs may remain load balanced based on algorithm data even after disabling all the feature configurations and clearing all the algorithm outputs. To rebalance all the APs based on the default method of site tags, reload the controller or perform a CAPWAP reset on all the APs.

Procedure

| Command or Action| Purpose
---|---|---
Step 1| configure terminal
Example:
Device# configure terminal| Enters global configuration mode.
Step 2| no wireless load-balance ap method rf
Example:
Device(config)# no wireless load-balance ap method rf| Disables RF-based AP load balancing.
Step 3| no ap neighborhood calendar-profile calendar-profile
Example:
Device(config)# ap neighborhood calendar-profile ap-calendar-profile| Disables the AP neighborhood calendar profile.
Step 4| exit
Example:
Device(config)# exit| Returns to privileged EXEC mode.
Step 5| ap neighborhood load-balance clear
Example:
Device# ap neighborhood load-balance clear| Clears the AP neighborhood load- balance algorithm calculation and resource allocation.

Verifying Automatic WNCd Load Balancing

To verify the results of the RF-based algorithm and the result of the related load balancing, use the following show commands.
To view the AP neighborhood summary, use the following show command:

To view the AP neighborhood details, use the following show command:

To view the AP neighborhood information, use the following show command:

To view the AP neighborhood details using its MAC address, use the following show command:

To view the WNCd information, use the following show command:

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