During the SCT Academy 2007, one of some topologies we had to do used to connect 5 routers 2811, one of them needed to have 4 serial interfaces, lack of luck, the flash card was in RMA. So I managed to boot the router without any flash card. Here is the explanations…
Turn on the router, without flash card, IOS is not found, pretty normal, so you will have the fabulous ROM monitor mode, something looking like this :
rommon1 >
You will have to set up the environments variables to download a IOS via TFTP and to load it in RAM, the step-by-step is the same as a disastrous recover :
rommon1 >IP_ADDRESS=10.0.0.2 rommon2 >IP_SUBNET_MASK=255.255.255.0 rommon3 >DEFAULT_GATEWAY=10.0.0.1 rommon4 >TFTP_SERVER=10.0.0.1 rommon5 >TFTP_FILE={your_ios}.bin
You could verify the good forms of your variables using this command :
rommon6 >set
Once everything’s ready, your TFTP’s server configured and up, you just have to invoke the command which will load your IOS in the RAM’s router and boot it.
rommon7 >tftpdnld -r
Verify that you use the port Fa0/0, by default in rommon, only this port can communicate.
