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APPENDIX B
ROM Monitor
This appendix describes the Cisco router ROM monitor (also called the bootstrap
program). The ROM monitor firmware runs when the router is powered up or
reset. The firmware helps to initialize the processor hardware and boot the
operating system software. You can perform certain configuration tasks, such as
recovering a lost password or downloading software over the console port, by
using the ROM monitor. If there is no Cisco IOS software image loaded on the
router, the RO
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Appendix B ROM Monitor Entering the ROM Monitor Follow these steps to configure the router to boot up in ROM monitor mode the next time it is rebooted. Command Router Prompt Task Router> Step 1 enable If there is an enable password configured, enter the enable command and the enable password to enter privileged EXEC mode. Step 2 Router# configure terminal Enter global configuration mode. Router(config)# Step 3 config-reg 0x0 Reset the configuration register. Step 4 Router(config)# exit Exit
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Appendix B ROM Monitor ROM Monitor Commands ROM Monitor Commands Enter ? or help at the ROM monitor prompt to display a list of available commands and options, as follows: rommon 1 > ? alias set and display aliases command boot boot up an external process break set/show/clear the breakpoint confreg configuration register utility cont continue executing a downloaded image context display the context of a loaded
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Appendix B ROM Monitor Command Descriptions Command Descriptions Table B-1 describes commonly used ROM monitor commands. Table B-1 Common ROM Monitor Commands Command Description help or ? Displays a summary of all available ROM monitor commands. -? Displays information about command syntax, for example: rommon 16 > dis -? usage : dis [addr] [length] The output for this command is slightly different for the xmodem download command: rommon 11 > xmodem -? xmodem: illegal option -- ? usage: xm
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Appendix B ROM Monitor Disaster Recovery with TFTP Download Table B-2 describes the ROM monitor boot commands. For more information about the ROM monitor boot commands, refer to the Cisco IOS Configuration Guide and Cisco IOS Command Reference publications. Table B-2 Boot Commands Command Description b Boots the first image in Flash memory. b flash: [filename] Attempts to boot the image directly from the first partition of Flash memory. If you do not enter a filename, this command will boot
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Appendix B ROM Monitor Disaster Recovery with TFTP Download Note The commands described in this section are case sensitive and must be entered exactly as shown in the lists. Required Variables The following variables must be set with the commands shown before using the tftpdnld command: Variable Command IP address of the router. IP_ADDRESS= ip_address Subnet mask of the router. IP_SUBNET_MASK= ip_address IP address of the default gateway of the DEFAULT_GATEWAY= ip_address router. IP address
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Appendix B ROM Monitor Disaster Recovery with TFTP Download Variable Command Number of times the router attempts TFTP_RETRY_COUNT= ARP and TFTP download. The default retry_times is 7. Amount of time, in seconds, before the TFTP_TIMEOUT= time download process times out. The default is 2400 seconds (40 minutes). Configures how the router displays file TFTP_VERBOSE= setting download progress. 0—No progress is displayed. 1—Exclamation points (!!!) are displayed to indicate file download progres
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Appendix B ROM Monitor Configuration Register Note The -r variable is optional. Entering this variable downloads and boots the new software but does not save the software to Flash. You can then use the image that is in Flash the next time you enter the reload command in the Cisco IOS software CLI. You will see output similar to the following: IP_ADDRESS: 10.0.0.1 IP_SUBNET_MASK: 255.255.0.0 DEFAULT_GATEWAY: 1.3.0.1 TFTP_SERVER: 223.255.254.254 TFTP_FILE: c1700
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Appendix B ROM Monitor Configuration Register This will change the virtual configuration register to the value specified. The value is always interpreted as hexadecimal. Entering confreg without an argument displays the contents of the virtual configuration register and a prompt to alter the contents by describing the meaning of each bit. Whether or not an argument is provided, the new virtual configuration register value is written into NVRAM, but it does not take effect until you reset or
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Appendix B ROM Monitor Console Download Console Download You can use console download, a ROM monitor function, to download over the router console port either a software image or a configuration file. After downloading, the file is saved either to Flash memory or to main memory for execution (image files only). Use console download when you do not have access to a TFTP server. Note If you want to download a software image or a configuration file to the router over the console port, you must
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Appendix B ROM Monitor Console Download Argument Description y Optional. Sets the router to perform the download using ymodem protocol. Default is xmodem protocol. The protocols differ as follows: • The xmodem protocol supports a 128-block transfer size, whereas the ymodem protocol supports a 1024-block transfer size. • The ymodem protocol uses 16-bit CRC error checking to validate each packet. Depending on the device that the software is being downloaded from, this function might not be su
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Appendix B ROM Monitor Debug Commands Debug Commands Most ROM monitor debugging commands are functional only when Cisco IOS software has crashed or stopped. If you enter a debugging command and Cisco IOS crash information is not available, you see the following error message: "xxx: kernel context state is invalid, can not proceed." The following are ROM monitor debugging commands: • stack or k—Produce a stack trace. For example: rommon 6> stack Stack trace: PC = 0x801111b0 Frame 00: FP = 0x
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Appendix B ROM Monitor Debug Commands R28 = 0xffffffff R29 = 0xffffffff R30 = 0xffffffff R31 = 0xffffffff • frame—Display an individual stack frame. • sysret—Display return information from the last booted system image. This information includes the reason for terminating the image, a stack dump of up to eight frames, and, if an exception is involved, the address where the exception occurred. For example: rommon 8> sysret System Return Info: count: 19, reason: user break pc:0x801111b0
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Appendix B ROM Monitor Debug Commands Cisco 1700 Series Router Software Configuration Guide 78-5407-03 B-14
