Cisco Cisco 2106 Wireless LAN Controller

Do not power down the controller or any access point during this process; otherwise, you might corrupt 
the software image. Upgrading a controller with a large number of access points can take as long as 30 
minutes, depending on the size of your network. However, with the increased number of concurrent 
access point upgrades supported in software release 4.0.206.0 and later, the upgrade time should be 
significantly reduced. The access points must remain powered, and the controller must not be reset 
during this time.

Before upgrading your controller to software release 5.1.163.0, you must comply with the following 
rules.

Make sure you have a TFTP or FTP server available for the software upgrade. Keep these guidelines 
in mind when setting up a TFTP or FTP server:

Controller software release 5.1.163.0 is greater than 32 MB; therefore, you must make sure that 
your TFTP server supports files that are larger than 32 MB. Some TFTP servers that support 
files of this size are tftpd and the TFTP server within the WCS. If you attempt to download the 
5.1.163.0 controller software and your TFTP server does not support files of this size, the 
following error message appears: “TFTP failure while storing in flash.”

If you are upgrading through the service port, the TFTP or FTP server must be on the same 
subnet as the service port because the service port is not routable, or you must create static 
routes on the controller.

If you are upgrading through the distribution system network port, the TFTP or FTP server can 
be on the same or a different subnet because the distribution system port is routable.

A third-party TFTP or FTP server cannot run on the same computer as WCS because the WCS 
built-in TFTP or FTP server and the third-party TFTP or FTP server require the same 
communication port.

You can upgrade or downgrade the controller software only between two releases. To upgrade or 
downgrade beyond two releases, you must first install an intermediate release. For example, if your 
controller is running a 4.2, 5.0, or 5.1 release, you can upgrade your controller directly to software 
release 5.1.163.0. If your controller is running a 3.2, 4.0, or 4.1 release, you must upgrade your 
controller to an intermediate release prior to upgrading to 5.1.163.0. 

 shows the upgrade path 

that you must follow before downloading software release 5.1.163.0.

3.2.78.0 or later 3.2 release

First upgrade to 4.0.155.5 and then upgrade to a 4.2 release before 
upgrading to 5.1.163.0.

4.0.155.5 or later 4.0 release

Upgrade to a 4.2 release before upgrading to 5.1.163.0.

4.1.171.0 or later 4.1 release

Upgrade to a 4.2 or 5.0 release before upgrading to 5.1.163.0.

4.2.61.0 or later 4.2 release

You can upgrade directly to 5.1.163.0.

5.0.148.0 or later 5.0 release

You can upgrade directly to 5.1.163.0.

5.1.151.0

You can upgrade directly to 5.1.163.0.