There are times when we have to upgrade Cisco IOS image. We can use traditional serial connections set up with 115200 baud rate, but will kill a great amount of time. We can use the PCMCIA cards to carry the IOS image from one router to another, but this requires you to have the card.

If you have a TFTP server set up, you can easily use the ethernet speed  to load the IOS to the destination. More recent routers seem to have a TFTP client built-into the ROMMON software. Not sure about how recent a router has to be in order to have this facility, but it’s very handy and saves a lot of time.

The basic idea behind this is that there are some environment variable which act as the source for the tftpdnld command – the command that used to download the IOS image file defined by TFTP_FILE from the TFTP_SERVER.

You need to configure the Hyper Terminal, or PuTTY. Since the previous is not available in Windows Vista go and get PuTTY from www.putty.org, if you are planning to work from Vista. Just set up the serial connection with 9600 bit rate with none flow control and then start the tasks that are described below.

Use the Ctrl + Break key combination to get the rommon> prompt. Run the set command to view the current set of variables that are confiugred.

Now configure the variables. Here, I used the IP addresses and image as per my convenience.

rommon 2 > IP_ADDRESS=192.168.10.125
rommon 3 > IP_SUBNET_MASK=255.255.255.0
rommon 4 > DEFAULT_GATEWAY=192.168.10.1
rommon 5 > TFTP_SERVER=192.168.10.10
rommon 6 > TFTP_FILE=c1841-advipservicesk9-mz.124-13a.bin
rommon 7 > tftpdnld
.
IP_ADDRESS: 192.168.10.125
IP_SUBNET_MASK: 255.255.255.0
DEFAULT_GATEWAY: 192.168.10.1
TFTP_SERVER: 192.168.10.10
TFTP_FILE: c1841-advipservicesk9-mz.124-13a.bin
TFTP_MACADDR: 20:04:31:30:15:1e
TFTP_VERBOSE: Progress
TFTP_RETRY_COUNT: 18
TFTP_TIMEOUT: 7200
TFTP_CHECKSUM: Yes
FE_PORT: 0
FE_SPEED_MODE: Auto Detect
.
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]: y
….
Receiving c1841-advipservicesk9-mz.124-13a.bin from 192.168.1.10 !!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
….
File reception completed.
Validating checksum.
Copying file c1841-advipservicesk9-mz.124-13a.bin to flash.
program load complete, entry point: 0×8000f000, size: 0xc100
.
Initializing ATA monitor library…….
.
Format: Drive communication & 1st Sector Write OK…
Writing Monlib sectors.
……………………………………………………………………..
………………
Monlib write complete
Format: All system sectors written. OK…
Format: Operation completed successfully.
Format of flash: complete
program load complete, entry point: 0×8000f000, size: 0xc100
Initializing ATA monitor library…….
rommon 17 >

Once that’s done, just issue a reset command and it should boot into IOS.

For Xmodem Console Download Procedure Using ROMmon Go to: http://www.cisco.com/en/US/products/hw/routers/ps259/products_tech_note09186a008015bfac.shtml#download_2620