This FAQ assumes that your router is able to boot up normally.
When your router is unable to boot up normally, please scroll down to the bottom of the page for suggestions.* Under any circumstances, DO NOT delete working IOS image off the flash memory unless the image has been backed up to server (TFTP or FTP server) or you have working IOS image stored in the server.
Your computer will then become TFTP server during the IOS image transfer.
A simple FREE one can be found here»Cisco Forum FAQ »How to prepare TFTP/FTP server Note that when the router is running newer IOS image, IOS image transfer using FTP server is also supported.
Keep in mind that maximize router DRAM and flash memory size before IOS image upgrade is always a good idea to make sure the router can fit the IOS image file and can run any IOS image version.
Check out the following FAQ to find memory specification»Cisco Forum FAQ »Cisco equipment memory chip specification* When the router is still running the older IOS image version, backup the older IOS image to TFTP or FTP server (the next steps explain this further).
Later description will show you how to back up the image* There is a chance that a router loses power or loses connection during the IOS image transfer (copy from or to server) which may cause the router to have no working IOS image to boot up from. Try the following* Backup image to TFTP server * Download image from TFTP server For those routers or switches that have USB port, you can use USB Flash drive to backup or to download IOS images as follows* Backup image to USB Flash drive * Download image from USB Flash drive Once you have both old and new IOS images in USB Flash drive, you can either save copies to your computer or to some storage such as DVD, tape backups, or some FTP servers.
Cisco IOS Software Upgrade Procedure for Cisco 801, 802, 803, 804, and 805 Series Routers2.This backup should perform before any IOS image upgrade.In case of unsuccessful IOS image upgrade (due to too-small DRAM size, corrupted IOS image, etc.) it is always a good to know that you are able to reverse the change by putting back the older IOS image (the one that you backup earlier) to the router In order to transfer an IOS image typically you need to run a TFTP program on your computer.Using TFTP server instead of using FTP server is more common however for image transfer.The rest of this FAQ shows the use of TFTP transfer however.
It is recommended that the PC (the TFTP server) is on the same subnet as your router.