This post comes to us from one of Cisco’s wireless specialists, Joe Rosado…WLAN 4.2 code has been released and posted to CCO. Prior to any code upgrade, it is recommended that you thoroughly read through the release notes to understand any open caveats that might affect your particular deployment. This blog post will serve as a quick guide to performing the software upgrade on your controller.

Step 1:
Release 4.2 of the WLAN controller code is greater than 32MB. Therefore, make sure that your TFTP server supports files larger than 32MB. You can download a free copy of TFTPD32 server here - http://tftpd32.jounin.net/tftpd32.htmlStep 2:
Verify the upgrade path that you have to follow in order to upgrade to 4.2 WLAN code. The following rules apply:a. If you are running 3.2.195.10 or later 3.2 release…..or
b. If you are running 4.0.206.0 or later 4.0 release…..or
c. If you are running 4.1.171.0 or later 4.1 release

You can upgrade directly to 4.2.61.0.

However, if you are running any of the following versions of code:

a. 3.2.78.0
b. 3.2.116.21
c. 3.2.150.10
d. 3.2.171.6
e. 3.2.193.5
f. 4.0.155.5
g. 4.0.179.11

You must upgrade to 4.0.206.0 (or later 4.0 release) prior to upgrading to 4.2. Also note that once you have upgraded to 4.0.206.0 (or later 4.0 release), you have to wait until all Access Points have rejoined the controller before continuing with the upgrade to 4.2.

Step 3:
Make sure that you backup your configuration file prior to performing this upgrade. This is extremely important as the config files have changed from binary files to xml-based configs with the 4.2 release. If you are forced to perform a downgrade and do not have a backup copy of your config file, you will have to rebuild your config from scratch. Also make sure to backup your current WLAN code to your TFTP server so you do not have to download it again.

Step 4:
This is where you download the code from CCO and TFTP it to the controller which is done via the web browser interface. You can find the code at the following location (just follow the wizard): http://www.cisco.com/public/sw-center/sw-wireless.shtml. If it is possible, it is a good idea to keep a console connection into the controller during this process so you can verify that the controller boots properly once the new code has been installed.

Step 5:
Download and install the 4.2 bootloader code for your particular controller. This code fixes a bootloader defect and is highly recommended by Cisco. You can download the code here:
http://tools.cisco.com/support/downloads/go/Redirect.x?mdfid=278875243

When you get to the software wizard, select Wireless LAN Controllers > Standalone Controllers > Wireless LAN Controller Software > All releases > 4.2. You will find the boot loader image here (the one that says BOOT).

Your controller and all of your Access Points are now upgraded to 4.2 WLAN code. In the event that you have to perform a downgrade back to a 4.1 release, please use the following procedure.

Step 1:
As stated in the upgrade procedure above, it is extremely important that prior to performing the 4.2 upgrade, you backup your current 4.1 (or prior) config first. You must locate this file and make sure it is accessible from your TFTP server.

Step 2:
Connect a console cable to the WLAN controller as you cannot perform this downgrade without console access.

Step 3:
Downgrade the WLAN code to your previous software release and reboot the controller. When the controller reboots, it will reboot to its factory default state. This is why you need to have a connection to the console. You will have to reconfigure the base configuration on the controller (ip addresses, username / password information, etc) again via the console. Once this is complete, you can connect to the controller via the web interface again.

Note that since the bootloader files are independent from the controller software files, you do not need to downgrade the bootloader file.

Step 4:
Locate and download your original configuration again.

Hopefully these steps will help you perform a successful upgrade to the new 4.2 WLAN code. For any further information, please refer to www.cisco.com/go/wireless.

Joe Rosado