Recovery Process of the Cisco IOS

Step 1: We need to enter the required information to the Router which it requires to recover the IOS from the Server. To see which information is required type the following command: 

Rommon 1 >tftpdnld

Step 2: Type the required information as shown below (These commands are case-sensitive)

Rommon 2 >IP_ADDRESS=10.0.0.1
Rommon 3 >IP_SUBNET_MASK=255.255.255.0
Rommon 4 >DEFAULT_GATEWAY=10.0.0.1
Rommon 5 >TFTP_SERVER=10.0.0.2
Rommon 6 >TFTP_FILE=Router-IOS.bin
Rommon 7 >tftpdnld
Rommon 8 >reset

As you can see, the IOS of the Router has been recovered from the TFTP Server and has been loaded successfully.

Cisco IOS is just like any other operating system and is used by routers and switches or other Cisco networking devices. Cisco IOS is a single image file that is stored in the flash memory in the case of Routers. When these routers are booted (powered on), the IOS stored in the Flash memory is loaded into the RAM.  If there is no IOS available in the Flash memory of the Router, the Router simply enters the ROMMON mode which allows us to install the IOS image file again. For the Backup process, we will be using TFTP (Trivial File Transfer Protocol). There is no need to go in depth of what TFTP really is or how it works, just know that it is a UDP-based file-transferring protocol used to read and write files from a remote server. Using TFTP, the transfer of files starts with a request to read or write files after requesting a connection. These file transfers take place only when the server grants the connection request.