How to recover a Cisco 2600 router and restore IOS

Boot in Rommon by interupting the boot of the router via a SEND BREAK on the Serial Console during the boot.

rommon 13 > TFTP_FILE=c2600-adventerprisek9-mz.124-16.bin

rommon 14 > IP_ADDRESS=10.1.1.3

rommon 15 > IP_SUBNET_MASK=255.255.255.0

rommon 16 > TFTP_SERVER=10.1.1.1

rommon 17 > tftpdnld

IP_ADDRESS: 10.1.1.3

IP_SUBNET_MASK: 255.255.255.0

DEFAULT_GATEWAY: 10.1.1.1

TFTP_SERVER: 10.1.1.1

TFTP_FILE: c2600-adventerprisek9-mz.124-16.bin

[…]

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

File reception completed.

Copying file c2600-adventerprisek9-mz.124-16.bin to flash.

Erasing flash at 0x62fc0000 program flash location 0×60030000

THIS TAKES A LONG TIME, depending on the size of the Flash memory and the generation of the Router.

tftpdnld → will erase the FLASH, boot from the specified IOS image and copy the IOS image to FLASH.

Alternatively if you still have an IOS available in FLASH, you can use this:

rommon 1 > dir flash:
         File size         Checksum   File name
5358032 bytes (0x51c1d0)   0x7b16    c2600-i-mz.122-10b.bin
rommon 2 > boot flash:c2600-i-mz.122-10b.bin

In worst case scenario’s, you can use the xmode – download procedure to download an IOS file accross your serial rollover – console cable for this puspose. You are highly adviced to change the config-register value in these cases to get the maximum baudrate out of your serial connection.

Example:

rommon 2 > xmodem -c c2600-is-mz.122-10a.bin
Here -c uses CRC-16
It is also important to note that the -s data-rate option is only available on the Cisco 1600 Series Routers and was implemented to overcome the console baud rate limitation of 9600 bps. 
If you specify -s data-rate of 115200 bps for example, you can increase the download rate and hence, reduce download time. Other Cisco routers support console speeds up to 115200 bps. Therefore, the -s data-rate option is not required.

The config – register is a means to change the baudrate as well.

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