The Cisco IOS® Software image running on a router dictates the features that will be available on the router and the commands that will be supported. There may be a situation that would require upgrading the Cisco IOS image running on a router to gain access to a desired feature, avoid a potential problem, or possibly enhance the performance of the router.

Again, the exact procedure for upgrading your Cisco IOS image may vary slightly across different platforms, but the general procedure for downloading the image remains the same.

You will need to have a Trivial File Transfer Protocol (TFTP) server set up with the Cisco IOS image file you want to upgrade to.

When you are able to access your TFTP server from your router, you can copy the image file to the Flash memory of the router using the "copy tftp flash" command.

It is wise to know exactly which Cisco IOS image file will work best for your network scenario and to use the appropriate image file, because this may severely impact the capabilities and performance of the router.

Click on the Configuration Lab icon to the right to open the interactive simulation environment window in a new browser.

To enter commands, activate the simulation environment Telnet window by clicking in it.

To see a list of supported commands at each step of the exercise, you can enter the ? command (press the question mark at the prompt). If you need more help, check the tutorial to review the configuration instructions.