Cisco CRS-1 - Carrier Routing System Router Getting Started Guide

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Cisco CRS-1 Series Carrier Routing System Getting Started Guide
Appendix A ROM Monitor Guide
Setting Configuration Register Values
Setting Configuration Register Values
The configuration register (config-register) is a 16-bit, user-configurable value that determines how the
router functions during initialization. The configuration register can cause the router to boot normally
from the default startup configuration, or to enter ROM monitor mode during a system reset. Typically,
ROM monitor mode is used only for password recovery or for software maintenance that cannot be
performed in Exec mode or global configuration mode.
The following sections describe how to change the configuration register settings from EXEC mode and
from ROM monitor mode:
• Commonly Used Configuration Register Value Settings, page A-6
• Changing the Configuration Register Setting from EXEC Mode, page A-6
• Changing the Configuration Register from ROM Monitor Mode, page A-8
Commonly Used Configuration Register Value Settings
To change the configuration register setting from normal operating mode, enter the config-register value
command. The most commonly used values are described in Table A-1.
Table A-1 Common config-register Settings
Note By default, the configuration register value is 0x2, which automatically boots the system to normal
EXEC mode.
Changing the Configuration Register Setting from EXEC Mode
To change the configuration register setting from normal operating mode, enter the config-register value
command.
Note To display the current configuration register setting, enter the show variables boot command in EXEC
mode.
Perform the following procedure in the order shown to ensure that the configuration register setting is
consistent between the Cisco IOS XR software and the ROM monitor of the Cisco CRS-1 router.
config-register Value Description
0x0 The router enters ROM monitor (
rommon B1>) on the next system boot.
0x2 The router boots the Cisco IOS XR software and configuration (EXEC mode) on the next
system boot.
0x40 The router enters the password recovery mode on the next system boot.

Cisco CRS-1 - Carrier Routing System Router Specifications

General

Brand	Cisco
Model	CRS-1 - Carrier Routing System Router
Category	Network Router
Language	English