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 loadbalance 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: 

Device# show ap neighborhood summary

NH-ID = Neighborhood ID
AREA-ID = Area ID of neighborhood

Total number of neighborhood: 5
Total number of algorithm iterations: 1
Ideal AP capacity per WNCD instance: 210

Total number of neighborhood area: 14

NH-ID      AREA-ID         Process Name   Number of APs
--------------------------------------------------
0          0x00000000      WNCD_1         1             
1          0x00000000      WNCD_0         2             
2          0x00000000      WNCD_0         100           
2          0x00000001      WNCD_0         100           
2          0x00000002      WNCD_3         100           
2          0x00000003      WNCD_4         50            
3          0x00000000      WNCD_1         100           
3          0x00000001      WNCD_1         100           
3          0x00000002      WNCD_4         100           
3          0x00000003      WNCD_4         50            
4          0x00000000      WNCD_2         100           
4          0x00000001      WNCD_2         100           
4          0x00000002      WNCD_3         100           
4          0x00000003      WNCD_3         50

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

Device# show ap neighborhood details

NH-ID = Neighborhood ID
AREA-ID = Area ID of neighborhood

Number of APs: 4

NH-ID   AREA-ID        WNCD instance    AP Name                 Ethernet MAC    
--------------------------------------------------------------------------------
0       0x00000000     1                EDU_BR_01_00_28_3702    bc16.6509.bfcc  
1       0x00000000     0                ci-glad-mdns-ap         0cd0.f894.567c  
1       0x00000000     0                EDU_VW_9120_1_2         c4f7.d54c.f978  
2       0x00000000     0                ewlc-hc-tsim-30-1       00b9.3000.02f0

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

Device# show ap neighborhood 0 details

NH-ID = Neighborhood ID
AREA-ID = Area ID of neighborhood

Number of APs: 1

NH-ID     AREA-ID          WNCD instance     AP Name              Ethernet MAC    
--------------------------------------------------------------------------------
0         0x00000000       0                 APA023.9FD8.EA22     a023.9fd8.ea22

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

Device# show ap neighborhood mac 0aa8.89f0.0001 details

NH-ID = Neighborhood ID
AREA-ID = Area ID of neighborhood

AP Name            Ethernet MAC    Radio MAC       NH-ID  AREA-ID     WNCD instance 
------------------------------------------------------------------------------------
AP6B8B4567-0001    0aa8.89f0.0001  0aa8.8900.0100  0      0x00000000  0

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

Device# show ap neighborhood wncd 0 details

NH-ID = Neighborhood ID
AREA-ID = Area ID of neighborhood

Number of APs: 9

WNCD instance     NH-ID       AREA-ID          AP Name          Ethernet MAC    
------------------------------------------------------------------------------------------------
0                 2           0x00000000       9130I-1          0c75.bdb5.ffc0  
0                 2           0x00000000       9130E-2          3c41.0efe.46f0  
0                 2           0x00000000       9120E-2          5ce1.7628.8bbc  
0                 2           0x00000000       9130I-2          e44e.2d2e.59d4  
0                 2           0x00000000       9120E-1          5ce1.7628.aa0c  
0                 2           0x00000000       9120E-3          5ce1.7628.af04  
0                 2           0x00000000       3700I-2          b838.6159.dfa4  
1                 0           0x00000000       3800I-2          6cb2.ae2e.dfdc  
2                 1           0x00000000       4800-1           f4db.e643.fa72  

NH-ID = Neighborhood ID
AREA-ID = Area ID of neighborhood
Number of APs: 5

WNCD instance    NH-ID   AREA-ID       AP Name             Ethernet MAC    
-----------------------------------------------------------------------
0                12      0x00000000    AP6B8B4567-0001     0aa8.89f0.0001  
0                12      0x00000000    AP6B8B4567-0004     0aa8.89f0.0004  
0                12      0x00000000    AP6B8B4567-0007     0aa8.89f0.0007  
0                12      0x00000000    AP6B8B4567-0010     0aa8.89f0.000a  
0                12      0x00000000    AP6B8B4567-0013     0aa8.89f0.000d