Erase a flash from Rommon mode

Discussion in 'Cisco' started by yadavdr, Aug 5, 2006.

  1. yadavdr

    yadavdr Guest

    Hello Friends,

    I want to erase all IOS from my flash. I am in ROMMON mode and I can
    not go to normal Router promt as my IOS is crashed. I am able to
    download the new IOS from Rommon mode by using tftpdnld or xmodem

    But after the Image download it is given while decompressing checksum

    I want to erase whole flash from rommon mode. Does any body know how to
    erase the total flash or IOS file from rommon mode.

    If any body know the command to erase the IOS from flash please please
    forward it to me...
    yadavdr, Aug 5, 2006
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  2. Why on earth do you want to do that? A router is not like a computer
    where you have a registry and little bits get left inside it that will
    screw other applications.
    A Cisco router is a nice piece of kit. I suggest that if you want rid
    of an image you boot up in normal mode and then up/downgrade the unit
    as normal.

    James Flockton
    James Flockton, Aug 5, 2006
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  3. yadavdr

    Merv Guest

    When you download the IOS image from CCO, there are checksums for the
    image listed on CCO. You nshould copy down these values.

    I suggest you check that the image did not get corrupted during the
    download from CCO. To do these verify the checksum of the image after
    it is on the device that you are going to use for a TFTP server.

    After you copy the IOS to you router, verify that the copy was okay by
    doing a

    "dir <device>" and verifying the checksum

    Suggest you post the model of the router and the IOS image you are
    trying to load. That way responders will be in a better position to
    assist you.
    Merv, Aug 5, 2006
  4. yadavdr

    MC Guest

    a router is a computer
    MC, Aug 5, 2006
  5. Which model? ROMMON command vary slightly from unit to unit.

    Can you capture the error? Sounds like you either

    - Loaded an image which is not compatible with your hardware
    - Loaded an image which won't fit in RAM.


    - What image name are you loading?
    - What hardware is this?
    - What is the exact error?

    Usually, routers will store the configuration and software in different
    palces (flash: and nvram:) but there are minor variations by platforms
    (especially 800 series)

    So... More details. The config file will not cause a crash unless there is
    a specific bug triggered by the config and that almost never ever happens.

    If you suspect the config is a problem, you can set the unit to boot up and
    IGNORE the config file using the confreg command in ROMMON (tell it to
    ignire config file during the questions).

    I suspect your real issue is an incompatible system image loaded into the
    unit. ROMMON doesn't check compatability.

    Also, I have seen some of the older platforms fail with a checksum error
    even if the image is good. This usually indicates a hardware failure of
    some fort, either with the flash itself or the flash controller. I saw a
    few 3800 series suffer this in their flash (slot0:)
    Phillip Remaker, Aug 5, 2006
  6. Yes a router is a computer.... Duh. What do you think it is? A straw
    hat perchance?
    James Flockton, Aug 6, 2006
  7. yadavdr


    Jul 10, 2006
    Likes Received:
    Hello ,

    I know this is dated, but I thought I'd actually offer a solution to your problem rather than plugging how great Cisco gear is as I'm sure you didn't voluntarily get yourself in this jam. I am in a similar situation myself. My problem is basically this:

    1. upgraded flash to 32megs
    2. loaded 28meg IOS code
    3. reset the router
    4. router attempted to load IOS three times and crashed each time because I didn't have enough RAM in which to inflate the IOS image.
    5. after failing to boot it popped me into rommon.

    So I'm sitting in the same boat as you (kinda): I have a non-bootable router with code on my flash that I wish to have erased. What I did was amazingly simple; I just tftp'd down my previous image. The erasing of the flash is implied and actually warned about when you're about to pull something in over tftp.

    "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"

    Hope this helps. I'll stir the pot on the router debate: yes, a router is a computer. A switch is a multi-port bridge. "A flute without holes, is not a flute. A donut without a hole, is a Danish."
    bugmenot, Apr 6, 2007
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