Upgrade an IOS on a Cisco Router
Before Starting procedure you need to download and install a TFTP server on your PC
There are many Free TFTP server just download one and install your PC.
Create a consol connection with the default setting
To your TFTP server put the IOS file which IOS you want to install of your router.
Run the Following Command
Router#copy tftp flash
Address or name of remote host ? 192.168.111.3 [This IP is your TFTP Server IP]
Source filename ? c1700-sy7-mz.123-15.bin [This file name is your IOS file name]
Destination filename [c1700-sy7-mz.123-15.bin]? [Hit Enter or if you want change file name then type new file name]
Erase flash: before copying? [confirm] [hit Enter]
Then it erase your existing IOS and it will install your new IOS.
Route#show run | include boot