Installing IOS on a Cisco Device

Preparing Resources

You’ll need the following piece of equipment:

• Old Toshiba with a serial console port
  • Toshiba will also need to have a TFTP Server application, a terminal emulator, and the IOS of the router. To make sure that the IOS is the correct one, I would double-check with other routers of the same model. You can grab the IOS of the internet.
• Ethernet Cable
• Console Cable
• Router with a storage device in it

Step by Step Process

• Make sure you have all of your resources from above ready to go. Plug the old Toshiba in with power because it will probably die, plug the console port from the router into the serial port of the Toshiba, and plug the Ethernet cord into the Toshiba to the first available port on the router.
• Turn on the router if you haven’t already. Console into the router with your terminal emulation program. You’ll need to boot into rommon mode, but if the router has nothing on its flash storage it will probably automatically.
• Once in rommon you’ll need to edit a couple of variables to use the tftpdnld command, you can just use the same variables I used. Type the following into the console:
  • IP_ADDRESS=192.168.0.2
  • IP_SUBNET_MASK=255.255.255.0
  • DEFAULT_GATEWAY=192.168.0.2
  • TFTP_SERVER=192.168.0.1
  • TFTP_FILE=(whatever the name of the IOS file is)
• That’s all you need to do on the router side for now. Now we need to configure a couple of things on the Toshiba.
• Go into the networking of the Toshiba and change the IP address and the subnet mask to 192.168.0.2 and 255.255.255.0
• Open up your TFTP Server application and you’ll need to configure a couple of settings. I used TerraTerm (download link below.)
  • Go to File>Configure
• Under the General tab:
  • Make sure you have a TFTP Server Root Directory, this will be located on the root of your C drive.
  • Also, make sure the status of the TFTP server is “Started”
• Under Server Binding make sure “Bind to all addresses on the machine” is checked
• Under Security make sure “Send and Recieve files” is on and “Allow all IP addresses to send/receive files”
• You are done setting up your TFTP Server.
• Now make sure that you have the IOS file in the TFTP-Root directory. This is where the router will be pulling from.
• Move back over to the terminal emulation program and type in tftpdnld. This starts the process, say yes to the yes/no question. It should start throwing a back of exclamation marks back at you (or maybe something else depending on the router.) You will also see in your TFTP Server application that a file get started. Check this to confirm that it is working.
• Once the router finishes grabbing the ISO it will tell you. You can then type in the command “reset” to restart the router. It should just boot into the IOS and you can use it as a router again.

Troubleshooting/Errors

• After this entire process, if the router starts to boot loop you may have installed the wrong IOS version.

Helpful Resources

• https://www.solarwinds.com/free-tools/free-tftp-server #TFTP Server app I used
• https://ttssh2.osdn.jp/index.html.en #TerraTerm used to access the Router console
• https://www.cisco.com/c/en/us/support/docs/routers/2600-series-multiservice-platforms/12714-76.html #Cisco’s documentation page is for 2600 series but I got it to work with an 1800 series