Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

PDF

Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

Enhanced site tag-based load balancing

Updated: April 10, 2026

Want to summarize with AI?

Log in

Explains enhanced site tag-based load balancing concepts, prerequisites, use cases, configuration procedures, and verification commands for optimizing wireless network performance.

A site tag-based load balancing is a controller mechanism that

  • distributes APs across Wireless Network Control Daemon (WNCD) processes based on site tags,

  • allows configuration of a site load for each site tag to optimize AP assignment considering site size, and

  • automatically retains site tags in persistent memory and balances them during controller bootup in descending order of the configured site load.

The controller takes the load balancing decision for a site tag when the first AP from that site tag joins.
Table 1. Feature History

Feature

Release

Feature Information

Enhanced Site Tag-Based Load Balancing

Cisco IOS XE Dublin 17.10.1

When the first AP from a site joins the controller, it takes the decision to load balance the entire site. However, this is done without knowing the site load.

How controllers functioned before load balancing

Previously, controllers did not consider the actual size of sites when making load balancing decisions. The system functioned optimally only when all sites were of approximately equal size. Unequal distribution caused some WNCDs to be overloaded while others remained underused.

The enhanced feature enables administrators to specify a site load for each site tag, ensuring the controller takes site size into account when distributing APs and thus resulting in improved load distribution among WNCDs.

Behavior during controller reboot

  • After you configure site load balancing in one or more site tags and reboot the controller, The feature retains actively used site tags and balances them at bootup by prioritizing those with higher configured site load before any APs join.

  • If load balancing is configured for a site tag with APs already joined, load balancing assignments remain unchanged unless all APs, including those not in the site tag, disconnect or the controller is rebooted.

assigning a higher site load to one site over the other

Suppose Site Tag X is assigned a higher site load than Site Tag Y. Upon controller bootup, APs from Site Tag X are distributed among WNCDs before those from Site Tag Y, helping prevent excessive load on any single WNCD even if Site Tag X contains many more APs than Site Tag Y.

Analogy: assigning classes to school buses

Think of enhanced site tag-based load balancing like assigning students from different-sized classes (site tags) to school buses (WNCDs). If you ignore class size, you might put all students from the largest class on a single bus, overloading it while leaving other buses half empty. By taking class sizes into account when assigning students, you distribute them more evenly and efficiently among the buses, preventing overcrowding and making better use of all resources. Similarly, by setting site load values, the controller assigns APs more fairly to WNCDs, balancing the work and avoiding overload.

Prerequisites for Enhanced Site Tag-Based Load Balancing

  • Ensure that you configure the site load.

  • We recommended that you configure all the named sites with a load value.

    Note

    The configured load is only an estimate. It will only be used for site load balancing. Specifically, it does not prevent APs, or clients from joining or associating.

Use cases

The site load configuration uses a load factor instead of an absolute number to address different use cases. Although the load factor does not have to match the number of APs in a site, using the AP count often provides a practical approximation of the site load.

Here are the use cases:

  • Sites with normal client density and roaming load can use AP count as a good approximation of site load. Examples include cubicle areas in offices and hospitals.

  • For sites with high client density and roaming load, configure a load factor greater than the number of APs. For example, when a site has 200 APs, use a load factor of 300 or 400 to accommodate the increased client load. Examples include stadiums, cafeterias, and conference floors.

Configure site load (CLI)

Assign a relative load value to a site tag using CLI. This helps the system optimize resource allocation and network performance for wireless deployments.

Use this task when you need to set or adjust the load recommendation for a specific site on your wireless controller. The load value influences how resources are distributed across sites.

Before you begin

Identify the name of the site tag you want to configure.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Configure site tag and enter site tag configuration mode.

Example:

Device(config)# wireless tag site area1
3.

Configure the site load.

Example:

Device(config-site-tag)# load 200

The load is the estimate of the relative load reserved for the site. Values range between zero to 1000. The default value zero means no load recommendation for the site.

4.

Return to privileged EXEC mode.

Example:

Device(config-site-tag)# end

The controller uses the configured load value for the specified site tag to optimize network resource allocation for that site

What to do next

Optionally, verify your changes by displaying the site tag configuration and confirming the new load value.

Verify enhanced site tag-based load balancing configuration

To view detailed information about a site, use the command:

Device# show wireless tag site detailed area1
Site Tag Name        : area1
Description          : 
----------------------------------------  
AP Profile           : default-ap-profile
Local-site           : Yes
Image Download Profile: default
Fabric AP DHCP Broadcast : Disabled
Fabric Multicast Group IPv4 Address : 239.1.1.1
Site Load            : 200

To view the default site tag type for Wireless Network Controller daemon (WNCD) instances, use the command:

Device# show wireless loadbalance tag affinity
Tag           Tag type    No of AP's Joined   Wncd Instance
-----------------------------------------------------------------------
area1         SITE TAG                   50         0
area2         SITE TAG                   50         0         
area3         SITE TAG                   100        1         
area4         SITE TAG                   150        2