This will help you to install the router IOS to a Cisco 2500/2600/2800/3800 series routers. First make sure, you have installed and configured any TFTP (Trivial File Transfer Protocol) server in the computer where you will attach your router for recovery. To download TFTP Server software ,Click Here. After downloading and installing the TFTP server, connect your router with this pc using one Console cable and one LAN cable.LAN cable can be attached on any Ethernet port of the router. Now start the HYPERTERMINAL utility and bootup your router.
If you are trying to boot up your router without an IOS, the nonworking router will boot up in ROMMON mode and the router first prompt will look like this:
rommon>
Now type the following information, for example router ip address, mask and default gateway then tftp server address.
rommon 3 > IP_ADDRESS=10.1.1.2 (router ip address)
rommon 4 > IP_SUBNET_MASK=255.0.0.0 (default subnet mask)
rommon 5 > DEFAULT_GATEWAY=10.1.1.1 (gateway address)
rommon 6 > TFTP_SERVER=10.1.1.1 (tftp server address)
rommon 7 > TFTP_FILE=12.0(4)t (IOS file name)
Make sure that IP Address of your PC to which you have connected the router and you install the tftp server should be of same series. To get the detail knowledge of IP Addressing (Click here)
Now again run the tftpdnld command to start recovery process immediately.
rommon 8 > tftpdnld
IP_ADDRESS: 10.1.1.2
IP_SUBNET_MASK: 255.0.0.0
DEFAULT_GATEWAY: 10.1.1.2
TFTP_SERVER: 10.1.1.1
TFTP_FILE: 12.0(4)t
Invoke this command for disaster recovery only.
WARNING: all existing data in all partitions on flash will be lost!
Do you wish to continue? y/n: [n]: Yes
Receiving 12.0(4)t from 10.1.1.1 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
File reception completed.
Copying file 12.0(4)t to flash.
Erasing flash at 0x60100000
Now run the reset command to restore router as factory default settings.
rommon 16 > reset
Now after some time, your router will boot up with factory default settings.
To tidy that up here is the full list of commands to issue at the ROMMON command line to copy a IOS from a TFTP server
copying the IOS using TFTP (only works on some routers with a more modem Boot Flash)
IP_ADDRESS=IP address of the Ethernet port
IP_SUBNET_MASK=subnet mask of the Ethernet port
DEFAULT_GATEWAY=The IP address of your Local Computer or TFTP Server
TFTP_SERVER=the IP of the TFTP server (your local computer)
TFTP_FILE=the file name of the IOS file.
tftpdnld
Just make sure you have the TFTP server running on a pc and the required IOS ready to go.
