Upgrade DSL firmware on a Cisco Router

I had to upgrade the firmware on a Cisco 877 recently so thought I would outline the best way to do this.

Firstly download your ADSL firmware from Cisco, you will need a Smart Net Contract for this. The file will be something like adsl_alc_20190.3.0.017.bin

Next you need to TFTP the file to the router, I use a basic TFTP Server and save the file in the root of the flash, you may notice there is not an existing firmware file for the routers current firmware. This is normal if you have an embedded firmware with the IOS, you can check this with the show version command and then look for the output for F/W and see if it is set to embedded.

Once you have TFTP the file to the Cisco you can then rename it removing the version number part

adsl_alc_20190.3.0.017.bin is renamed to adsl_alc_20190.bin

Then you reboot the router and the firmware is loaded.