Cisco 800 Series Routers

ROMmon Recovery for the Cisco 800 Series Router

Document ID: 15083

Updated: Dec 18, 2007



This document describes how to recover a Cisco 800 series router if you are blocked in TinyRom (the boot# prompt).



There are no specific requirements for this document.

Components Used

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

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


For more information on document conventions, refer to the Cisco Technical Tips Conventions.

ROMmon Recovery Procedure

First, determine whether you still have a valid Cisco IOS® Software image in Flash.

Use the list command to display the files stored in Flash:

boot# list
Status     Size     Dev    Name
------       48K  flash    TinyROM-1.0(2)
------       48K  flash    TinyROM-1.0(3)
--Dr-x     2600K  flash    c800-y6-mw.120-5.T
---r-x     2863K  flash    c800-y6-mw.121-5   

!--- Here it is

           5184K  free     8192K total

The image is valid if it has a status of "---r-x".

If the "x" is not present, the image is probably corrupted, and needs to be deleted. Use the delete [filename] command to mark it as deleted, and the erase command to effectively delete all files marked deleted.

If "D" is present, the image has been marked deleted. You can restore a deleted image using the undelete [filename] command.

Note: The eighth time you delete a particular file, the file is permanently deleted, and the undelete [filename] command no longer works for that filename.

The following sections discuss these scenarios:

No Valid Cisco IOS Software Image in Flash

Without a valid Cisco IOS Software image in Flash, you have four different options:

If you have booted from a TFTP server, your router should now be operational, even though you do not have a Cisco IOS Software image in Flash.

Note: If your router is rebooted without being connected to the TFTP server, you will end up in TinyROM again.

If you have downloaded an image, you should now have a valid Cisco IOS Software image in Flash, but you still have to boot it. To do so, follow the procedure in the Valid Cisco IOS Software Image in Flash section.

Valid Cisco IOS Software Image in Flash

With a valid Cisco IOS Software image in Flash, all you need to do is, set the variables boot-action, file-name, and ios-conf to their correct values like this:

boot# set boot-action=?
set boot-action    ={flash|tftp|none}
Default boot action to take on power up:
 flash  => run file-name from flash.
 tftp   => tftp file-name (script or image) into RAM, then run it.
 none   => enter CLI and wait for commands from user
boot# set boot-action=flash
boot# set file-name=c800-y6-mw.121-5 

!--- Or, whatever is your valid Cisco IOS Software image filename.

boot# set ios-conf=0x2102

Save the new values, and then boot the router using the boot command:

boot# save
save: succeeded (0 seconds).
boot# boot
Booting "c800-y6-mw.121-5" ...,
              Restricted Rights Legend
Use, duplication, or disclosure by the Government is
subject to restrictions as set forth in subparagraph
(c) of the Commercial Computer Software - Restricted
Rights clause at FAR sec. 52.227-19 and subparagraph
(c) (1) (ii) of the Rights in Technical Data and Computer
Software clause at DFARS sec. 252.227-7013.
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           170 West Tasman Drive
           San Jose, California 95134-1706

Related Information

Updated: Dec 18, 2007
Document ID: 15083