Software Configuration Guide
Using the ROM Monitor
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Table Of Contents

Using the ROM Monitor

Entering the ROM Monitor Mode

Configure

Verify

ROM Monitor Commands

ROM Monitor Syntax Conventions

Command Descriptions

Debugging Commands

Configuration Register Commands

Using the show rom-monitor Command

Using the upgrade rom-monitor Command

Procedures for Recovering Boot and System Images

Using the xmodem Command

Using the tftpdnld Command


Using the ROM Monitor

This appendix describes the ROM monitor (also called the bootstrap program), which is the firmware that runs when you power on or restart the Cisco 2600 series, Cisco 3600 series, and Cisco 3700 series router. During normal operation, the ROM monitor helps to initialize the processor hardware and boot the operating system software. You can also use the ROM monitor to help you isolate or rule out hardware problems encountered when installing your router.

This appendix contains the following sections:

•Entering the ROM Monitor Mode

•ROM Monitor Commands

•ROM Monitor Syntax Conventions

•Command Descriptions

•Procedures for Recovering Boot and System Images

Entering the ROM Monitor Mode

To use the ROM monitor, you must have access to the console port. See the Cisco 2600 Series Cabling and Setup Quick Start Guide for information on connecting the console cable.

To enter ROM monitor mode, do the following:

Configure

 
Command or Action
Purpose

Step 1  

2600> reload

Restarts the router.

Step 2 

Press the Break key during the first 60 seconds while the system is starting up

Forces the router to stop booting and enter the ROM monitor mode.


Verify

To verify that you are in the ROM monitor mode, check that the prompt displayed on your screen is the ROM monitor mode prompt: 

rommon # >

The # is the line number and increases incrementally at each prompt.

Tip From the Cisco IOS software, you can configure the router to automatically enter the ROM monitor mode the next time the router boots by setting virtual configuration register bits 3, 2, 1, and 0 to zero. From the console, enter the following configuration command: 

configuration-register 0x0

The new configuration register value, 0x0, is effective after the router is rebooted with the reload command. The router remains in the ROM monitor and does not boot the operating system.

As long as the configuration register value remains 0x0, you must manually boot the operating system from the console. Refer to the boot command in the section "Command Descriptions" later in this appendix.

ROM Monitor Commands

Enter ? or help at the ROM monitor mode prompt to display a list of available commands. For example: 

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 image

cookie      display contents of cookie PROM in hex

dev         list the device table

dir         list files in the file system

dis         display instruction stream

dnld        serial download a program module

frame       print out a selected stack frame

help        monitor builtin command help

history     monitor command history

meminfo     main memory information

repeat      repeat a monitor command

reset       system reset

set         display the monitor variables

stack       produce a stack trace

sync        write monitor environment to NVRAM

sysret      print out info from last system return

tftpdnld    tftp image download

unalias     unset an alias

unset       unset a monitor variable

xmodem      x/ymodem image download

rommon 2 >

Note You can abort any command by pressing the Break key at the console.

Note The command tftpdnld is present in the Cisco 2600 series routers only.

Note The command upgrade rom-monitor is present in the Cisco 3700 series routers only.

ROM Monitor Syntax Conventions

The ROM monitor syntax in this appendix uses the following conventions:

•Square brackets [ ] denote an optional element. In the following example, the element abc is not required, but you can specify it if you choose:

command [abc]

•If a minus option is followed by a colon (for example, [-s:]) you must provide an argument for the option.

•A term in italics means that you must fill in the appropriate information. In the following example, you replace the term in italics with the interface type you are using: 

command type interface

Command Descriptions

This section lists some useful ROM monitor commands. Refer to the Cisco IOS configuration guides and command references for more information on ROM monitor commands.

Note The commands show rom-monitor, showmon, upgrade rom-monitor , upgrade rom-monitor preference, rommon-pref are present in the Cisco 3700 series routers only. The command tftpdnld is present in the Cisco 2600 series routers only.

•boot or b—Boots an image.

–Boots from the first IOS image in flash memory.

–flash:[name] boots the Cisco IOS software from the flash memory.

–filename tftpserver boots from the specified file over the network from the specified TFTP server. For example: 

boot c2600-i-mz 172.15.19.11

–filename boots from the boothelper image, because it does not recognize the device ID. This form of the command is used to netboot the image named filename.

•The Cisco 2600 series router does not have a dedicated boothelper image ([rx]boot) as used by some other Cisco routers. With the Cisco 2600 series router, the first image in flash memory is invoked as the default boothelper image anytime the ROM monitor does not recognize the device ID in the boot command.

•You can override the default boothelper image setting by setting the BOOTLDR Monitor environment variable to point to another image. Any system image can be used for this purpose.

•Options to the boot command are -x, load image but do not execute, and -v, verbose.

•Use the Cisco IOS commands show version and show hardware to display the source of the currently running image.

–dir device:[partition:]—Lists the files on the named device. For example: 

rommon 8 > dir flash:


         File size               Checksum   File name

       2229799 bytes (0x220627)   0x469e    C2600-j-m2.113-4T

–help—Displays a summary of ROM monitor commands (equivalent to ?).

–meminfo—Displays size in bytes, starting address, available range of main memory, the starting point and size of packet memory, and size of nonvolatile memory (NVRAM). The following example shows the meminfo command: 

rommon 9 > meminfo


Main memory size: 32 MB.

Available main memory starts at 0xa000e000, size 32704KB

IO (packet) memory size: 25 percent of main memory.

NVRAM size: 32KB

•meminfo [-l]—The meminfo command with the -l option displays supported DRAM configurations. The following example shows an example of the meminfo -l command: 

rommon 10 > meminfo -l


Supported memory configurations:


DIMM 0       DIMM 1

-------------------

             4M

             8M-DUAL

             16M

              32M-DUAL

4M

4M           4M

4M           8M-DUAL

4M           16M

4M           32M-DUAL

8M-DUAL

8M-DUAL      4M

8M-DUAL      8M-DUAL

8M-DUAL      16M

8M-DUAL      32M-DUAL

16M

16M          4M

16M          8M-DUAL

16M          16M

16M          32M-DUAL

32M-DUAL

32M-DUAL     4M

32M-DUAL     8M-DUAL

32M-DUAL     16M

32M-DUAL     32M-DUAL

•reset or i—Resets and initializes the router, similar to power on.

•show rom-monitor— Shows version of read-only ROMMON, and if present, the upgrade version of ROMMON. It also shows the current version of ROMMON, which version will be selected for execution when the Cisco IOS software is booted again. This command isavailable in the Cisco IOS exec mode.

–showmon—Available in the ROMMON command mode. Provides the same information as the show rom-monitor command in the Cisco IOS exec mode.

•upgrade rom-monitor <file<URL>|preference<readonly|upgrade>>—Installs and reloads a new version of ROMMON in the Cisco IOS exec mode. URL refers to the path where the new ROMMON image is stored. Prompts the user to save the configuration.

–upgrade rom-monitor preference<readonly|upgrade>—Selects the version of ROMMON to be loaded the next time the router is reloaded. This command is used in the Cisco IOS exec mode.

–rommon-pref—Used in ROMMON command mode. Provides the same information as upgrade rom-monitor preference command in the Cisco IOS exec mode.

Debugging Commands

Most debugging commands are functional only when Cisco IOS software has crashed or is aborted. If you enter a debugging command and Cisco IOS crash information is not available, the following error message appears: 

"xxx: kernel context state is invalid, can not proceed."

•stack or k—Produces a stack trace.

•context—Displasy processor context.

•frame—Displays an individual stack frame.

•sysret—Displays 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: a SegV exception

pc:0x802b1040,  error address: 0x802b1040

Stack Trace:

FP: 0x80908398, PC: 0x802b102c

FP: 0x809083b0, PC: 0x802b0b88

FP: 0x809083d8, PC: 0x8017039c

FP: 0x809083e8, PC: 0x8016f764

Configuration Register Commands

The virtual configuration register resides in NVRAM. You can display or modify the virtual configuration register from either the ROM monitor or the operating system software.

To change the virtual configuration register from the ROM monitor, enter the confreg command by itself for menu mode, or enter the new value of the register in hexadecimal.

•confreg [hexnum]—Changes the virtual configuration register to the value specified. The value is always interpreted as hexadecimal.

Note Entering confreg without an argument displays the contents of the virtual configuration register and prompts you to alter the contents by describing the meaning of each bit. In either case, the new virtual configuration register value is written into NVRAM, but is not effective until you reset or power-cycle the router.

The following display shows an example of the confreg command: 

rommon 7 > confreg



    Configuration Summary

enabled are:

break/abort has effect

console baud: 9600

boot: the ROM Monitor


do you wish to change the configuration? y/n  [n]:  y

enable  "diagnostic mode"? y/n  [n]:  y

enable  "use net in IP bcast address"? y/n  [n]: 

enable  "load rom after netboot fails"? y/n  [n]: 

enable  "use all zero broadcast"? y/n  [n]: 

disable "break/abort has effect"? y/n  [n]: 

enable  "ignore system config info"? y/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  [0]:  0

change the boot characteristics? y/n  [n]:  y

enter to boot:

 0 = ROM Monitor

 1 = the boot helper image

 2-15 = boot system

    [0]:  0



    Configuration Summary

enabled are:

diagnostic mode

break/abort has effect

console baud: 9600

boot: the ROM Monitor


do you wish to change the configuration? y/n  [n]: 



You must reset or power cycle for new config to take effect

Using the show rom-monitor Command

Note The show rom-monitor command is present in the Cisco 3700 series routers only. The command tftpdnld is present in the Cisco 2600 series routers only.

The show rom-monitor command displays the current version of the read-only ROM monitor, and if present displays the upgrade version of the ROM monitor. The upgrade version is selected when the system is rebooted. This command runs in the Cisco IOS exec mode.

You get the following output, when the read-only ROM monitor is present: 

Router# show rom-monitor 

ReadOnly ROMMON version:

System Bootstrap, Version 12.2(4r)XT2, RELEASE SOFTWARE (fc1) 

TAC Support: http://www.cisco.com/tac 

Copyright (c) 2001 by cisco Systems, Inc.

No upgrade ROMMON programmed or not yet run 

Currently running ROMMON from ReadOnly region 

ROMMON from ReadOnly region is selected for next boot

Router#

Following is an example of an output when both the read-only and the upgrade versions of the ROM moinitor are present: 

Router# show rom-monitor 

ReadOnly ROMMON version:

System Bootstrap, Version 12.2(4r)XT4, RELEASE SOFTWARE (fc1) 

TAC Support: http://www.cisco.com/tac 

Copyright (c) 2001 by cisco Systems, Inc.

Upgrade ROMMON version:

System Bootstrap, Version 12.2(8r)T1, RELEASE SOFTWARE (fc1) 

TAC Support: http://www.cisco.com/tac 

Copyright (c) 2002 by cisco Systems, Inc.

Currently running ROMMON from Upgrade region 

ROMMON from Upgrade region is selected for next boot

Router#

Note You can get the same information if you enter the showmon command in the ROMMON command mode.

Using the upgrade rom-monitor Command

Note The command upgrade rom-monitor is present in the Cisco 3700 series routers only.

To upgrade the ROM monitor to a new version, use the upgrade rom-monitor command. Depending on where the image is located, use the following commands to upgrade the ROM monitor:

•upgrade rom-monitor file <URL>

•upgrade rom-monitor preference <readonly | upgrade>

The upgrade rom-monitors file <URL> command installs the new version of ROM monitor on the router by taking the image from the location indicated in the URL. The image is in the form of ".srec' file. It then reloads the router.

Following is an example of the output when the upgrade version of ROM monitor is located at tftp://223.255.254.254/ajayhn/c3745_RM2.srec:, and the system configuration has not been saved: 

Router# upgrade rom-monitor file tftp://223.255.254.254/ajayhn/C3745_RM2.srec 


Loading ajayhn/C3745_RM2.srec from 223.255.254.254 (via FastEthernet0/0): 
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 

[OK - 641719/1283072 bytes]

This command will reload the router. Continue? [yes/no]: y

System configuration has been modified. Save? [yes/no]: y 

Building configuration...

Erasing boot flash eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee 

Programming boot flash pppp

Now Reloading 

System Bootstrap, Version 12.2(4r)XT4, RELEASE SOFTWARE (fc1) 

TAC Support: http://www.cisco.com/tac 

Copyright (c) 2001 by cisco Systems, Inc.

Running new upgrade for first time

System Bootstrap, Version 12.2(8r)T1, RELEASE SOFTWARE (fc1) 

TAC Support: http://www.cisco.com/tac 

Copyright (c) 2002 by cisco Systems, Inc. 

c3745 processor with 196608 Kbytes of main memory 

Main memory is configured to 64 bit mode with parity disabled 


Upgrade ROMMON initialized 

rommon 1 >

Following sample output shows a configuration that has been saved: 

Router# upgrade rom-monitor file tftp://223.255.254.254/ajayhn/C3745_RM2.srec 

Loading ajayhn/C3745_RM2.srec from 223.255.254.254 (via FastEthernet0/0): 
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 

[OK - 641719/1283072 bytes]

This command will reload the router. Continue? [yes/no]: y

Erasing boot flash eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee 

Programming boot flash pppp

Now Reloading 

System Bootstrap, Version 12.2(4r)XT4, RELEASE SOFTWARE (fc1) 

TAC Support: http://www.cisco.com/tac 

Copyright (c) 2001 by cisco Systems, Inc.

Running new upgrade for first time

System Bootstrap, Version 12.2(8r)T1, RELEASE SOFTWARE (fc1) 

TAC Support: http://www.cisco.com/tac 

Copyright (c) 2002 by cisco Systems, Inc. 

c3745 processor with 196608 Kbytes of main memory 

Main memory is configured to 64 bit mode with parity disabled 


Upgrade ROMMON initialized 

rommon 1 >

Note The rommon-pref command in the ROMMON command mode provides the same information as the 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.

Note The command tftpdnld is present in the Cisco 2600 series routers only.

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—Uses cyclic redundancy check (CRC-16)

•-y—Uses Ymodem transfer protocol

•-r—Copies the image to DRAM for launch

•-x—Does not launch image on completion of download

Using the tftpdnld Command

Note The command tftpdnld is present in the Cisco 2600 series routers only.

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—IP address for the router you are using.

–IP_SUBNET_MASK—Subnet mask for the router you are using.

–DEFAULT_GATEWAY—Default gateway for the router you are using.

–TFTP_SERVER—IP address of the server from which you want to download the image file.

–TFTP_FILE—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.

The syntax for specifying the variables is: 

VARIABLE_NAME=value

After you specify the variables, you must reenter the tftpdnld command. For example: 

rommon 1 > tftpdnld

rommon 2 > IP_ADDRESS=172.15.19.11

rommon 3 > IP_SUBNET_MASK=255.255.255.0

rommon 4 > DEFAULT_GATEWAY=172.15.19.1

rommon 5 > TFTP_SERVER=172.15.20.10

rommon 6 > TFTP_FILE=/tftpboot/c2600-i-mz

rommon 7 > TFTP_VERBOSE=1

rommon 8 > tftpdnld


     IP_ADDRESS=172.15.19.11

     IP_SUBNET_MASK=255.255.255.0

     DEFAULT_GATEWAY=172.15.19.1

     TFTP_SERVER=172.15.20.10

     TFTP_FILE=/tftpboot/2600-i-mz

     TFTP_VERBOSE=1


Invoke this command for disaster recovery only.

WARNING: all existing data in flash will be lost!

Do you wish to continue? y/n: [n]:

Enter y to begin downloading the Cisco IOS software image. When the process is complete, the ROM monitor mode prompt appears on your screen.