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Cisco Broadband Cable Command Reference Guide
OL-1581-07
Appendix A Using the ROM Monitor
confreg
confreg
To change the value of the router’s configuration register, use the
confreg
command in ROM monitor
mode.
confreg
[
value
]
Syntax Description
Defaults
0x2102 (boots the Cisco IOS software image and allows the use of the BREAK signal to enter
ROMMON)
Command Modes
ROM monitor
Command History
Usage Guidelines
The configuration register determines the router’s behavior when it boots. Typically, an administrator
changes the configuration register so that it boots either into ROMMON mode or boots a Cisco IOS
software image, but other options are also available.
If given without an argument, the
confreg
command interactively prompts you for the new values of the
individual register settings, using English descriptions. You can either keep the current settings
unchanged or change them as desired. The new value of the configuration register is written into the
router’s nonvolatile Flash memory (NVRAM) immediately, but does not take effect until you reset the
router.
If you specify an argument with the
confreg
command, it must be a 16-bit hexadecimal value in the
following format:
value
(Optional) New value for the configuration register, expressed as a 16-bit
hexadecimal value. The valid range for
value
is 0x0 to 0xFFFF. If
value
is not
specified, the command interactively prompts you for the individual register
settings.
Release
Modification
11.3 NA
This command was introduced on Cisco uBR7200 series routers.
12.1(5)EC
Support was added for Cisco uBR7100 series routers.
12.2(4)BC1
Support was added for the Cisco uBR10012 router.
Table A-1
Configuration Register Bit Field Descriptions
Bit
Description
15
If set, enables the router’s diagnostic mode (for example, 0x8000).
14
If set, uses the network number in IP broadcasts (for example, 0x4000).
13
If set, allows the router to fall back into ROMMON mode if the boot procedure fails.
If not set, the router attempts each valid
boot
command (as specified by bits 3–0) for
a total of 5 times each, until one of the commands is successful (for example,
0x2000).