B-9
Cisco 3600 Series Routers Hardware Installation Guide
OL-2056-05
Appendix B Using the ROM Monitor
Recovering Cisco IOS Software Images
Recovering Cisco IOS Software Images
If both the boot and system images have been erased and only the ROM monitor is available, you can
use the ROM monitor xmodem command to copy a Cisco IOS image to Flash memory from the console.
The console can be connected directly to the router through the console port, or remotely through a
modem connected to the auxiliary port.
Note Copying a Cisco IOS image from the console is very slow. This procedure should be used only
in an emergency and is not recommended for normal Cisco IOS image upgrades.
For the fastest possible download from a console, set the console speed to 115200 bps by using
the confreg ROM monitor command. See the “Configuration Register Commands” procedure
on page B-7.
Note Using a PCMCIA card to update the Cisco IOS image is much faster than using the console port
and, when available, is the recommended method of recovering a software image.
Description and Options of 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 argument 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 dynamic random-access memory (DRAM) for launch.
• x—Do not launch image on completion of download.
Console Requirements
The console computer (PC) must have the following files to use this procedure:
• Terminal emulation application program supporting one of the following file transfer protocols:
–
Xmodem
–
Xmodem–CRC
–
Xmodem–1K
–
Ymodem
• Cisco IOS image file
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