C-8
Software Configuration Guide for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Routers
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Appendix C Using the ROM Monitor
Entering the ROM Monitor Mode
Note
rommon-pref in the ROMMON command mode provides the same information as upgrade
rom-monitor preference command in the Cisco IOS Exec mod.
Procedures for Recovering Boot and System Images
If your router experiences difficulties and no longer contains a valid Cisco IOS software image in Flash
memory, you can recover the Cisco IOS image using one of the following ROM monitor commands:
•
xmodem—Use this if the computer attached to your console has a terminal emulator that has
xmodem capability.
•
tftpdnld—Use this if you have a TFTP server directly connected to the Ethernet 0 port.
Using the xmodem Command
The xmodem command establishes a connection between a console and the router console port for
disaster recovery if both the boot and system images are erased from Flash memory.
xmodem [filename]—Establishes an xmodem connection between the console and the router. The
optional parameter filename specifies the source file containing the Cisco IOS image.
Other options include the following:
•
-c—use cyclic redundancy check (CRC-16)
•
-y—use Ymodem transfer protocol
•
-r—copy the image to DRAM for launch
•
-x—do not launch image on completion of download
Using the tftpdnld Command
The tftpdnld command downloads a Cisco IOS software image from a remote server into Flash memory
using TFTP.
tftpdnld—Begins the TFTP copy command.
The following variables are required:
–
IP_ADDRESS—The IP address for the router you are using.
–
IP_SUBNET_MASK—The subnet mask for the router you are using.
–
DEFAULT_GATEWAY—The default gateway for the router you are using.
–
TFTP_SERVER—The IP address of the server from which you want to download the image file.
–
TFTP_FILE—The name of the file that you want to download.
–
The following variables are optional:
–
TFTP_VERBOSE—Print setting. 0=quiet, 1=progress, 2=verbose. The default is 1.
–
TFTP_RETRY_COUNT—Retry count for ARP and TFTP. The default is 7.
–
TFTP_TIMEOUT—Overall timeout of the download operation in seconds. The default is 2400
seconds.
–
TFTP_CHECKSUM—Performs a checksum test on the image. 0=no, 1=yes. The default is 1.