Cisco 4400 Series Wireless LAN Controllers

How to Use the Backup Image on Wireless LAN Controllers (WLCs)

Document ID: 107530

Updated: Nov 17, 2011



This document explains how to use the backup image on a Wireless LAN Controller (WLC).



Cisco recommends that you have knowledge of these topics:

  • Knowledge of how to configure the WLC and Lightweight Access Point (LAP) for basic operation

  • Basic knowledge of Lightweight Access Point Protocol (LWAPP)

Components Used

The information in this document is based on these software and hardware versions:

  • Cisco 2000 / 2100 / 4400 Series WLC that runs firmware 5.0

  • LWAPP-based access points, Series 1230, 1240, 1130, 1250, 1140 and 1500

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


Refer to Cisco Technical Tips Conventions for more information on document conventions.

Primary and Backup Images on WLCs

The WLC, by default, maintains two images. These images are the primary image and the backup image. The primary image is the active image used by the WLC while the backup image is used as a backup for the active image.

The controller bootloader (ppcboot) stores a copy of the active primary image and the backup image. If the primary image becomes corrupted, you can use the bootloader to boot with the backup image.

You can change the active image in two ways.

Assuming that the WLC has a valid backup image, reboot the controller. During the boot process on the WLC, press the Esc key in order to see the additional options.

This output shows an example:

Initializing memory.  Please wait.  256 MB SDRAM detected
BIOS Version: SM 02.00
BIOS Build date: 09/17/02
System Now Booting ...

Booting from disk..., please wait.

Cisco Bootloader Loading stage2...

    Cisco Bootloader (Version

                      .o88b. d888888b .d8888.  .o88b.  .d88b.
                     d8P  Y8   `88'   88'  YP d8P  Y8 .8P  Y8.
                     8P         88    `8bo.   8P      88    88
                     8b         88      `Y8b. 8b      88    88
                     Y8b  d8   .88.   db   8D Y8b  d8 `8b  d8'
                      `Y88P' Y888888P `8888Y'  `Y88P'  `Y88P'

Booting Primary Image...
Press <ESC> now for additional boot options...

    Boot Options

Please choose an option from below:

 1. Run primary image (Version (active)
 2. Run backup image  (Version
 3. Manually upgrade primary image
 4. Change active boot image
 5. Clear Configuration

Choose Option 4: Change Active Boot Image from the boot menu to set the backup image as the active boot image. Now, when the controller resets, it boots with the new active image.

You can also change the active booting image of the WLC manually with the config boot <primary/backup> command.

Syntax Description


Each Cisco WLC can boot off the primary, last-loaded OS image or boot off the backup, earlier-loaded OS image. In order to change a Cisco WLC boot option, issue the config boot command. By default, the primary image on the controller will be chosen as the active image.


> config boot primary
> config boot backup

In order to configure the boot order using the WLC GUI, complete these steps:

  1. From the WLC GUI, navigate to the Commands page.

  2. From the Commands on the left, click Config Boot.

    The Config Boot Image page appears.


    This page displays the Primary and Backup images presently available on the controller, and also indicates the Active image.

  3. In order to change the Active image, select the desired image from the image drop-down menu and click Apply.


    In this example, Backup is selected.

  4. Save the configuration and reboot.

When the WLC reboots and comes back up, it will boot with the backup image.

When you upgrade the WLC with a new image, the WLC automatically writes the new image as the primary image and the previously existing primary image is written over the backup image.

Note: The previously existing backup image will be lost.

In order to see the active image that your controller is currently running, click on Monitor from the WLC GUI and look at the Software Version field under Controller Summary on the controller GUI. From the CLI, you can issue the show boot command to view the primary and backup image present on the WLC. Here is an example:

(Cisco Controller) >show boot
Primary Boot Image...............................
Backup Boot Image................................ (active)

In order to remove or overwrite an image on the WLC, boot up the WLC with the image that you want to keep and perform an upgrade. This way, the new image replaces the primary image.

Related Information

Updated: Nov 17, 2011
Document ID: 107530