QuickTip added by adhawkin on Mon Apr 30 12:11:36 PDT 2002
Recovery from booting to rommon
Introduction: What does this document describe? How to recover from botting into rommon mode on 3600 series routers. What problem is the customer having that this document will solve? Customer copied an IOS image that required more flash than they had available on their 3640 router.
Versions: What hardware and software versions did you use to develop this document? Customer was suing 11.2(16) and wanted to upgrade to 12.1(4.5)
Use this field to input your configuration steps or
The steps below outline how to connect and download another image using
XMODEM through the console port of the router.
How to download an image using xmodem when routers 3600 and 2600 goes into
Problem:- The router is in ROMMON prompt and when it is reloaded it again
goes into ROMMON prompt.
To solve the above problem, you can download an image to the 2600 and 3600
using the console port of the router.
The procedure uses the default console speed of 9600 bits per second.
Xmodem is a slow transfer protocol. Increasing the console speed (which is
for the Cisco 2600 and 3600 series routers) helps decrease the time it
takes to do the xmodem file transfer.
3600 / 2600 in rommon
1- rommon > b ———- to boot first image in flash mem
2- rommon > dir flash: ———- list the files on the device
3- rommon > meminfo ———- to see memory information
You are in rommon and
1- when “b” is typed the router comes back in rommon.
2- dir flash: reveals an invalid check sum.
3- So the last solution is to download an image using xmodem
When in ROMMON mode, follow the procedure below Using the ROMMON confreg
rommon 2 > confreg
do you wish to change the configuration? y/n [n]: y
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]: y
enter rate: 0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400
4 = 19200, 5 = 38400, 6 = 57600, 7 = 115200 : 7
change the boot characteristics? y/n [n]: y
enter to boot:
0 = ROM Monitor
1 = the boot helper image
2-15 = boot system
load rom after netboot fails
console baud: 115200
boot: the ROM Monitor
do you wish to change the configuration? y/n [n]: n
You must reset or power cycle for new config to take effect
rommom 2 > reset
The next step is to open a new hyperterminal with settings as follows,
Bits per second – 115200
Data bits – 8
Parity – None
Stop bits – 1
Flow control – Hardware
After setting the hyperterminal you get a rommon prompt, and type the
xmodem command. Before typing an xmodem command there should be a software
residing in your terminal or your local C drive.
rommon 2 > xmodem -c c3640-i-mz.121-7.bin
Do not start the sending program yet…
File size Checksum File name
4936800 bytes (0x4b5460) 0x2dd7 c3640-i-mz.121-7.bin (bad checksum:
WARNING: All existing data in flash will be lost!
Invoke this application only for disaster recovery.
Do you wish to continue? y/n [n]: y
Ready to receive file c3640-i-mz.121-7.bin …
After the above message appears u have to download the file using xmodem,
the procedure is as follows,
1) Go to Hyperterminal, click Transfer
2) Click on send file
3) click on browse ——– look for the file name in your local “C”
4) Below filename field is Protocol ——- change it to xmodem
5) And then clik on send
After some time the router will reload itself and will ask you “Press
return to get stated”
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#line con 0
Router(config-line)# speed 9600 ——— Change the speed of the
console port to 9600
Then go to Hyperterminal and change baud rate to 9600 in your terminal.
Router #write mem