How to Upgrade from ROMmon Using the Boot Image

Posted on 1:03 AM by Bharathvn


This page describes how to upgrade a router from the ROM monitor (ROMmon) prompt using the TFTP functionality of the boot image.



There are no specific requirements for this document.

Components Used

This document is not restricted to specific software and hardware versions.


Refer to Cisco Technical Tips Conventions for more information on document conventions.

What Is the Boot Image? (Rx-boot)

The boot image is a subset of the Cisco IOS® software that is used to download main Cisco IOS software images to the router using TFTP in recovery situations. The user can interact with this image through a command line interface signified by the prompt Router(boot)#. Some platforms (Cisco 1600, 2500) have it in ROM; others (high-end routers) have it in bootflash. This image can be called xboot image, rxboot image, bootstrap image, or boot loader or helper image, which depends on your platform.

The boot image has limited capabilities. For example, it does not contain routing information.

Warning: Never save your configuration while in boot mode, as part of the configuration (such as the routing part) is lost if saved this way.

Loading the Boot Image

If the router contains a valid boot image, it can be used to download a valid Cisco IOS Software image into the Flash using TFTP. In order to do this, perform these steps:

  1. Change the configuration register to boot the boot image by setting the configuration register as follows (depending on the prompt you have):

    rommon 1 > confreg 0x2101
    > o/r 0x2101
    You must reset or power cycle for the new configuration to take effect.
    !--- This is the router output when a configuration register command is entered.

    The configuration register has now been changed to boot the boot image.

  2. Boot the boot image by resetting the router:

    rommon 2 > reset

    > i

    The System Bootstrap message appears and the router boots its boot image. On the screen, you should see something like this:

    System Bootstrap, Version 11.1(10)AA, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)
    Copyright (c) 1997 by cisco Systems, Inc.
    C1600 processor with 18432 Kbytes of main memory
    program load complete, entry point: 0x4018060, size: 0x1e1568
    Restricted Rights Legend


    !--- Output omitted.




    You should now have a prompt similar to Router(boot)>.

  3. If you are still in ROMmon, that means your boot image is either missing or corrupted. If your router has no valid image in Flash or Bootflash, and no other ROMmon upgrade procedure, the only way to recover is to have a similar router with a compatible Flash card, download the image on that router, and then move the Flash card to the one that is stuck.

  4. Check the PCMCIA Filesystem Compatibility Matrix and Filesystem Information for Flash card compatibility information.

  5. Connect the Ethernet interface 0 of your router to the network, through which you can reach the TFTP server. Configure the IP address on the Ethernet interface of the router.

    Router(boot)#configure terminal
    Router(boot)(config)#interface ethernet 0
    Router(boot)(config-if)#ip address
    Router(boot)(config-if)#no shutdown
  6. Routers that run boot images do not have routing capabilities. Therefore, a default gateway for this router must be configured. Issue the ip default-gateway global configuration command to set the appropriate default gateway for this router. This should point to the IP address of the router attached to the same subnet as your Ethernet 0 interface.

    Router(boot)(config)#ip default-gateway
  7. Before you copy the Cisco IOS image from the TFTP server, make sure that the router has connectivity to the TFTP server.

    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echoes to, timeout is 2 seconds:

    Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms

  8. Copy the Cisco IOS image from the TFTP server to the Flash memory on the router.

    Router(boot)#copy tftp flash
    PCMCIA flash directory:
    No files in PCMCIA flash
    [0 bytes used, 16777216 available, 16777216 total]
    Address or name of remote host []?
    !--- Enter the IP address of the TFTP Server.
    Source file name? c1600-y-l.122-10d.bin
    !--- This is the filename of the Cisco IOS image that you want to copy from
    !--- the TFTP server.
    Destination file name [c1600-y-l.122-10d.bin]?
    !--- Press 'Enter'.
    Accessing file 'c1600-y-l.122-10d.bin' on
    Loading c1600-y-l.122-10d.bin from (via Ethernet0):
    ! [OK] Device needs erasure before copying new file
    Erase flash device before writing? [confirm]y

    !--- Press 'y' or 'Enter'.
    !--- On Class B Flash file systems, the router gives you the option of erasing
    !--- the existing contents of Flash memory before writing to it. If no free Flash
    !--- memory is available, or if no files have ever been written to Flash memory,
    !--- the erase routine is required before new files can be copied. If there is
    !--- enough free Flash memory, the router gives you the option of erasing the
    !--- existing Flash memory before writing to it. The system will inform you
    !--- of these conditions and prompt you for a response.
    !--- If you enter 'n' after the "Erase flash before writing?" prompt, the copy
    !--- process continues. If you enter 'y' and confirm the erasure, the erase
    !--- routine begins. Make sure to have ample Flash memory space before entering "n"
    !--- at the erasure prompt.

    Copy 'c1600-y-l.122-10d.bin' from server as 'c1600-y-l.122-10d.bin' into Flash
    WITH erase? [yes/no]yes
    !--- Entering 'yes' erases all the files in Flash.

    Erasing device... eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

    eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ...erased

    Loading c1600-y-l.122-10d.bin from (via Ethernet0): !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    [OK - 7220632/16777216 bytes]Verifying checksum... OK (0x6526)

    Flash device copy took 00:05:57 [hh:mm:ss]

  9. Change the configuration register value back to 2102 for the router to boot with the newly downloaded Cisco IOS image during the next reload.

    Router(boot)#configure terminal
    Router(boot)(config)#config-register 0x2102
  10. Reload the router by issuing the reload command.

    System configuration has been modified. Save? [yes/no]: no

    Building configuration...


    Proceed with reload? [confirm]
    !--- Press 'Enter'.
    %SYS-5-RELOAD: Reload requested

    System Bootstrap, Version 11.1(10)AA, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)
    Copyright (c) 1997 by cisco Systems, Inc.
    C1600 processor with 18432 Kbytes of main memory
    program load complete, entry point: 0x4018060, size: 0x1e1568


    !--- Output omitted.



  11. To verify if the correct image has been loaded into the router, check the Cisco IOS image version in the router by issuing the show version command.

    Router>show version
    Cisco Internetwork Operating System Software
    IOS (tm) 1600 Software (C1600-Y-L), Version 12.2(10d), RELEASE SOFTWARE (fc1)
    Copyright (c) 1986-2003 by cisco Systems, Inc.
    Compiled Wed 14-May-03 01:04 by pwade
    Image text-base: 0x0803A510, data-base: 0x02005000

    ROM: System Bootstrap, Version 11.1(10)AA, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)

    ROM: 1600 Software (C1600-BOOT-R), Version 11.1(10)AA, EARLY DEPLOYMENT RELEASE
    SOFTWARE (fc1)

    1603 uptime is 19 hours, 26 minutes

    System returned to ROM by reload

    System image file is "flash:c1600-y-l.122-10d.bin"

    cisco 1603 (68360) processor (revision C) with 13824K/4608K bytes of memory.

    Processor board ID 10240382, with hardware revision 00000000

    Bridging software.

    X.25 software, Version 3.0.0.

    Basic Rate ISDN software, Version 1.1.

    1 Ethernet/IEEE 802.3 interface(s)

    1 ISDN Basic Rate interface(s)

    System/IO memory with parity disabled

    2048K bytes of DRAM onboard 16384K bytes of DRAM on SIMM

    System running from FLASH

    7K bytes of non-volatile configuration memory.

    16384K bytes of processor board PCMCIA flash (Read ONLY)

    Configuration register is 0x2102


    You are now running the new Cisco IOS image that has been loaded from a TFTP server.