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Recover a Router from Corrupted or Missing Software Image
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Introduction
This document explains on how to recover your Cisco Router from corrupt
or missing software image. This procedure applies to the 800, 1700, 1800, 2600,
2800 and 3800 models of Cisco routers.
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Requirements
To perform the steps described in this document, you need to have these
items:
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Physical access to the Router that is installed and powered
on
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A Windows PC with terminal-emulation software, such as
HyperTerminal.
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A cross-over cable and a console cable. Refer to
Cable
Descriptions for further information.
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A new Cisco IOS software image provided to you by the
SMB
Technical Assistance Center (SMB TAC).
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Obtain the Software Image File
Follow these steps to obtain a new software image:
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If your Router software image is corrupted or missing, contact the
SMB
TAC to obtain the required software image.
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Once you receive the software, take note of the exact name of the
image file.
The file has a similar name to this example:
c2600-i-mz.122-28.bin
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Place the software image file in your C:\TFTP-Root
directory.
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Connect the PC to the Router
Complete these steps to connect the PC to the Router:
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Connect your RJ-45 Ethernet port of your PC to the first LAN port
or FastEthernet port or Gigabit Ethernet port of the router with a cross-over
Ethernet cable.
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Configure your PC with the IP address 192.168.10.2
and with a subnet mask of 255.255.255.0. For detailed
instructions, refer to
Configure
an IP Address on Your PC.
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Save the router software image in your C:\TFTP-Root directory. If
you do not have a new image, contact the
SMB
Technical Assistance Center (SMB TAC) for
assistance.
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Launch your TFTP server program.
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Connect your PC to the router with a console cable. You need a
console access to your router in order to boot the router with a new software
image.
Note: Create a HyperTerminal connection to your router. For more
information, refer to
Create a
HyperTerminal Connection.
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Recover the Router from ROMmon mode
Follow these steps to recover the Router from the ROMmon mode:
Check Configuration Register Settings
Use this procedure to recover the router from the ROMmon mode, before
you try to upgrade the router software image with the TFTP server. You can use
this, only if your flash has a valid IOS software image.
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If the router is stuck in ROMmon mode each time the router is
restarted, it is probably due to the setting of the configuration register.
Type confreg at the ROMmon prompt to verify the configured
value of the configuration register. You can see the similar
output:
rommon 1 >confreg
Configuration Summary
(Virtual Configuration Register: 0x2100)
enabled are:
load rom after netboot fails
console baud: 9600
boot: the ROM Monitor
do you wish to change the configuration? y/n [n]:
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In the output of the confreg command, the
configuration register is set to a value 0x2100 that forces
the router to go into the ROMmon mode each time it is reloaded or power-cycled.
To make the router boot automatically from a default Cisco IOS software image,
change the configuration register to a value 0x2102 as
indicated in step 3.
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Type confreg at the ROMmon prompt. Enter
y in response to the question “do you wish to change the
configuration” in the output.
rommon 2 >confreg
Configuration Summary
enabled are:
load rom after netboot fails
console baud: 9600
boot: the ROM Monitor
do you wish to change the configuration? y/n [n]:y
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Enter n to all questions except to the question
“change the boot characteristics? y/n [n]:. Enter
y to change the boot characteristics? y/n [n]:
y and enter digit 2 in enter to
boot:
enable "diagnostic mode"? y/n [n]:n
enable "use net in IP bcast address"? y/n [n]:n
disable "load rom after netboot fails"? y/n [n]:n
enable "use all zero broadcast"? y/n [n]:n
enable "break/abort has effect"? y/n [n]:n
enable "ignore system config info"? y/n [n]:n
change console baud rate? y/n [n]:n
change the boot characteristics? y/n [n]:y
enter to boot:
0 = ROM Monitor
1 = the boot helper image
2-15 = boot system
[0]:2
Configuration Summary
(Virtual Configuration Register: 0x2102)
enabled are:
load rom after netboot fails
console baud: 9600
boot: image specified by the boot system commands or default to: cisco2-c3825
do you wish to change the configuration? y/n [n]: n
You must reset or power cycle for new config to take effect
Note: You have changed the configuration register to a value that makes
the router to look for a valid Cisco IOS software image on startup and boot
from the same. Reset the router now.
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Type reset at the ROMmon
prompt.
rommon 3 >reset
System Bootstrap, Version 12.3(11r)T1, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2004 by cisco Systems, Inc.
Total memory size = 256 MB - DIMM0 = 256 MB, DIMM1 = 0 MB
c3825 processor with 262144 Kbytes of main memory
Main memory is configured to 72/0(dimm 0/1) bit mode with ECC enabled
Upgrade ROMMON initialized
program load complete, entry point: 0x8000f000, size: 0xc0c0
Initializing ATA monitor library.......
program load complete, entry point: 0x8000f000, size: 0xc0c0
Initializing ATA monitor library.......
program load complete, entry point: 0x80010000, size: 0x22f97a8
Self decompressing the image : #################################################
########################################################################## [OK]
----Output truncated---
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The router must now reload with the new Cisco IOS software image.
If the router still goes to ROMmon mode proceed to the section
Look for a Valid Image in
Flash.
Look for a Valid Image in Flash
If the configuration register value is set to make the system boot
automatically from a default Cisco IOS software image, the router must boot
normally. However, if the router still enters the ROMmon mode, it is probably
because the device is unable to locate a valid Cisco IOS software image.
Follow these steps to look for a valid Cisco IOS software
image.
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Type dev at the ROMmon prompt to display the file
system that you use such as a flash or slot or disc.
rommon 1 >dev
Devices in device table:
id name
flash: compact flash
bootflash: boot flash
eprom: eprom
rommon 2 >
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Identify the router file system and type dir
<file-system> which lists the files and directories in the file
system. The keyword
file-system
is either
a flash or slot or disc. For example if you use flash file system type
dir flash: at the ROMmon prompt to look for a valid
image.
rommon 2 >dir flash:
program load complete, entry point: 0x8000f000, size: 0xc0c0
Initializing ATA monitor library.......
Directory of flash:
2 36673864 -rw- c3825-advipservicesk9-mz.124-12.bin
4424 1649 -rw- sdmconfig-38xx.cfg
4425 4052480 -rw- sdm.tar
5415 812032 -rw- es.tar
5614 1007616 -rw- common.tar
5860 1038 -rw- home.shtml
5861 113152 -rw- home.tar
5889 756288 -rw- 256MB.sdf
0 0 -rw- config_log_persist_dbase
10524 1236 -rw- vlan.dat
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The output indicates that a valid image
c3825-advipservicesk9-mz.124-12.bin is indeed present in the
Flash. Try to boot from that image with the boot command as
specified in step 5.
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If the router returns the “dir: cannot open device
“flash:” or “bad device name" message, the device
specified probably does not exist. If you have a 2800 or 3800 ISR, try to reset
the flash card on the router or replace with the new one installed with IOS
image. After that, reload the router. If it goes to ROMmon again, go to step
1.
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Type " boot flash:[directory] [filename] " which
boots the router. For example "boot flash:<image-name>" or boot
slot<0/1>:<image-name> or boot disco<0/1>:<image name>,
depends on the file system you use.
rommon 2 >boot flash: c3825-advipservicesk9-mz.124-12.bin
program load complete, entry point: 0x8000f000, size: 0xc0c0
Initializing ATA monitor library.......
program load complete, entry point: 0x80010000, size: 0x22f97a8
Self decompressing the image : #################################################
################################################################################
########################################################################## [OK]
----output truncated----
Note: The router must now boot with the Cisco IOS software image
specified in the boot command.
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However, there are times when a valid image does not exist on any
of the devices or the image on the Flash is corrupted. In these cases, a new
Cisco IOS software image has to be downloaded with Trivial File Transfer
Protocol (TFTP) procedure from the ROMmon mode. Refer to the section
Load the new software image with the TFTP server
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Load the new software image with the TFTP server
This section describes how to load a Cisco IOS software image from a
TFTP server to the router flash memory. Use the procedure only for disaster
recovery, as it erases all the datas that exist in flash memory before a new
software image is downloaded to the router. Follow these steps to download a
new software image to the router with a TFTP server.
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First, you must set ROMmon environment variables prior to the TFTP
download. All variable names are case sensitive. You can view the ROMmon
environment variables by the the set command.
rommon 1 >set
PS1=rommon ! >
BOOT=
WARM_REBOOT=FALSE
?=0
BSI=0
RANDOM_NUM=628802873
RET_2_RTS=10:27:44 UTC Thu Jun 28 2007
RET_2_RCALTS=1183026467
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These variables are required to be set for TFTP
download:
IP_ADDRESS: The IP address for this router
IP_SUBNET_MASK: The subnet mask for this router
DEFAULT_GATEWAY: The default gateway for this router
TFTP_SERVER: The IP address of the TFTP server in which the software image is stored
TFTP_FILE: The software image filename to fetch
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At the rommon: command prompt in the HyperTerminal
window, type IP_ADDRESS=192.168.10.1 and press
Enter.
rommon 2 >IP_ADDRESS=192.168.10.1
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Type IP_SUBNET_MASK=255.255.255.0 and press
Enter.
rommon 3 >IP_SUBNET_MASK=255.255.255.0
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Type DEFAULT_GATEWAY=192.168.10.10 and press
Enter.
rommon 4 >DEFAULT_GATEWAY=192.168.10.10
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Type TFTP_SERVER=192.168.10.2 and press
Enter.
rommon 5 >TFTP_SERVER=192.168.10.2
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Type
TFTP_FILE=/tftpboot/spak/c3825-adventerprisek9-mz.124-12b.bin
and press Enter.
rommon 6 >TFTP_FILE= /tftpboot/spak/c3825-adventerprisek9-mz.124-12b.bin
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Type sync and press
Enter.
rommon 7 >sync
Note: The "sync" command is required to write the monitor environment
changes to NVRAM.
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Type tftpdnld and press Enter.
Enter y in response to the question “do you wish to continue?
y/n: [n]:” in the output.
rommon 8 >tftpdnld
IP_ADDRESS: 192.168.10.1
IP_SUBNET_MASK: 255.255.255.0
DEFAULT_GATEWAY: 192.168.10.10
TFTP_SERVER: 192.168.10.2
TFTP_FILE: /tftpboot/spak/c3825-adventerprisek9-mz.124-12b.bin
GE_PORT: Ge0/0
TFTP_MEDIA_TYPE: Copper
GE_SPEED_MODE: Auto
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
Mac Address: 0017.5a41.2cf0
Receiving /tftpboot/spak/c3825-adventerprisek9-mz.124-12b.bin from 192.168.10.2 !!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
File reception completed.
Copying file /tftpboot/c3825-adventerprisek9-mz.124-12b.bin to flash.
program load complete, entry point: 0x8000f000, size: 0xc0c0
Initializing ATA monitor library.......
Format: All system sectors written. OK...
Format: Operation completed successfully.
Format of flash: complete
program load complete, entry point: 0x8000f000, size: 0xc0c0
Initializing ATA monitor library.......
rommon 7 >
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At the rommon prompt, type dir flash: to verify
the software image downloaded on to the flash memory.
rommon 7 >dir flash:
program load complete, entry point: 0x8000f000, size: 0xc0c0
Initializing ATA monitor library.......
Directory of flash:
2 40406296 -rw- c3825-adventerprisek9-mz.124-12b.bin
Note: You have downloaded the new image
c3825-adventerprisek9-mz.124-12b.bin onto the flash with the
TFTP server.
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Type boot flash:<filename> and press
Enter to boot the router with the new CiscO IOS software
image.
rommon 8 > boot flash:c3825-adventerprisek9-mz.124-12b.bin
program load complete, entry point: 0x8000f000, size: 0xc0c0
Initializing ATA monitor library.......
program load complete, entry point: 0x80010000, size: 0x2688b78
Self decompressing the image : #################################################
################################################################################
################################################################################
######### [OK]
Smart Init is enabled
smart init is sizing iomem
----output truncated---
Router >
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The router must now boot with the new Cisco IOS software image
specified in the boot command and it must be in Router >
prompt.
Note: For Cisco 2600 Routers which run the ROM monitor command
tftpdnld, the command reports a bad checksum comparison when
it loads Cisco IOS software images of Cisco IOS Software Release 12.0(2.2)T or
later. As a workaround to this problem, set the ROM monitor variable
TFTP_CHECKSUM to 0. The variable TFTP_CHECKSUM=0 is defined from the ROM
monitor set command, proceeded by the
tftpdnld procedure.
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Next Step
You have completed Recover your Access Point with the new software
image.
To continue the setup process, refer to
Configure
Your Router with Security Device Manager.
To configure other devices in your network, refer to the
Configuration
Overview Page.
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Troubleshoot the Procedure
This section provides information about common problems that you may
encounter. If this information does not solve your problem, contact the
SMB
Technical Assistance Center (SMB TAC) for assistance.
Problem
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Cause(s) and Suggested Solution(s)
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The router boots and displays several error messages but does
not display a prompt in HyperTerminal.
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Press Enter to clear the output and display
the router prompt.
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You receive an error message “Interface link did not
come up. Timed out. TFTP: Operation terminated” or “Timed
Out” after you perform step 12 of the Load the
new software image with the TFTP server section.
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Follow these steps:
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Ensure that the PC's IP address is configured with
192.168.10.2 with a subnet mask of
255.255.255.0. Refer to
Configure
an IP Address on Your PC for instructions.
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Ensure that you use the proper cable. You must use a
crossover cable not a straight-through cable to connect your PC to the router
first Ethernet port. Refer to
Cable
Descriptions for more information.
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Ensure that you have launched TFTP Server
program.
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You receive an error message:
TFTP error 1 received (File not found).
TFTP: Operation terminated.
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Ensure that the new software image is stored in your TFTP Root
directory and you have specified the correct file path in step 7 of
Load the new software image with the TFTP server
section.
If you are still unable to complete the procedure successfully,
contact the
SMB
Technical Assistance Center (SMB TAC) for assistance.
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Related Information
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