Despite having done this many many times. I still manage to not exactly recall all of the steps to load a software image onto a ASA in ROMMON mode. Today I had to do it again and managed to muddle my way through it using the ‘help’ commands. However, I neglected to recall that ping doesn’t work even after you assign the IP and interface. That fact lead to an hour of needless troubleshooting as I tried to determine why the ASA couldn’t ping my laptop over a crossover cable. So here we go….
Boot the ASA into ROMMON
Press break or escape key during boot
Configure the ASA with the information it will need to connect to the TFTP Server
You should now be at a ‘rommon #1>’ prompt. When Im doing a process like this I usually directly connect my laptop to the ASA with a crossover cable. That being said, I only need to enter in the following commands….
rommon #1> ADDRESS=<The IP you want to give the ASA>
rommon #2> SERVER=<The IP of the TFTP Server>
rommon #3> IMAGE=<The file name of the image you want to load>
rommon #4> PORT=<The port that you have the crossover plugged into>
This is all of info you need if the connection is layer 2. If your TFTP server is somewhere else on the LAN, you can use the ‘GATEWAY=<Default Gateway>’ command to set a default gateway
Copy the image
At this point all you have to do is enter in one last command to start the copy….
rommon #5> tftp
After the copy is complete, the ASA will load the new software image and you should be back in business!