How to perform Router Disaster Recovery

In most of the cases, if you powered on the router and the router is entering into rommon mode. The problem is 

1) IOS is missing

2) IOS is corrupted

You can perform backup / upgrade of IOS from ROMMON mode also. First connect your Router to the TFTP server where IOS image is located.

Now power on the router, router will enter into ROMMON mode.

1) Assign IP address to the LAN interface of the router that is connected to TFTP server in the same network

rommon1> IP_ADDRESS = 192.168.1.2

2) Assign Subnet Mask to the LAN interface of the router

rommon2> IP_SUBNET_MASK = 255.255.255.0

3) Assign Default Gateway

rommon3>DEFAULT_GATEWAY= 192.168.1.1

4) Assign ip address of the TFTP server where IOS image is located.

rommon4> TFTP_SERVER = 192.168.1.1

5) Mention the IOS file name which you want to load into the router.

rommon5>TFTP_FILE=c2800nm-advipservicesk9-mz.128-15.T2.bin

6) Download the IOS from TFTP server into Router flash

rommon6>tftpdnld

do you want to continue [y/n]: y

rommon7>reset