config-register
To define the configuration register boot value, use the config-register command in the appropriate mode.
config-register {value | boot-mode {exec-mode | rom-monitor} | console-baud baud-rate | console-break-key {disable | enable} | password-recovery {disable | enable}} [location {node-id | all}]
Syntax Description
value |
Hexadecimal or decimal value that represents the 16-bit configuration register value to be used the next time the router is reloaded. Range is from 0x0 to 0xFFFF (0 to 65535 in decimal). For information about common configuration register settings, see Table 1. |
boot-mode |
Specifies what to do when the system is rebooted. |
exec-mode |
Specifies to load the Cisco IOS XR software and enter EXEC mode on next system reboot. |
rom-monitor |
Specifies to enter ROM Monitor mode on next system reboot. |
console-baud baud-rate |
Specifies the console baud rate. |
console-break-key {disable | enable} |
Specifies to disable or enable the console break key on the next system reboot. |
password-recovery {disable | enable} |
Specifies to enable or disable the password recovery mode on the next reboot. |
location {node-id | all } |
(Optional) Specifies the RSP node for which to define the configuration register boot value. The all keyword specifies all RSP nodes. |
Command Default
By default, the configuration register value is 0x102 after a Turboboot.
Command Modes
Administration EXEC
EXEC mode
Command History
Release |
Modification |
---|---|
Release 3.7.2 |
This command was introduced. |
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
The configuration register setting is a 16-bit, user-configurable value that determines how the router switch processor (RSP) functions during initialization. The configuration register can cause the RSP to boot normally from the default configuration, or to enter ROMMON mode during a reload. Configuration register settings can also be used to perform tasks such as password recovery.
The config-register command is entered in administration EXEC mode, on the designated shelf controller (DSC) of the system. The DSC is the primary RSP of the owner secure domain router (owner SDR).
When you have two RPs (Primary RP0 and Standby RP1) and the config-registers of the two are different, you must manually set the config-register in RP1 equal to RP0 in order for RP1 to synchronize with the configurations on RP0.
Use the show variables boot command in the EXEC mode to see status of the config-register in both the RPs.
Use the config-register x locationx command in the Admin mode to change the config-register in either of the RPs.
When setting the configuration register value for the config-register command, note the following conditions:
-
If both the primary and standby DSC are up and running when the configuration register value is set, the configuration register value applies to both the primary and standby DSC.
-
By contrast, if only the primary DSC is up and running when the configuration register value is set and the standby DSC is introduced into the router at a later time, the router does not attempt to synchronize the configuration register value for the standby RSP to that of the active RSP; in this situation, the configuration register setting applied to the standby DSC is determined by the configuration register value set in ROMMON mode.
This table describes the most commonly used configuration register settings.
Value |
Description |
---|---|
0x0 |
RSP enters ROMMON mode (rommon B1>) on the next system boot. |
0x2 |
RSP loads the Cisco IOS XR software and default configuration on the next system boot. After logging in, the user can access EXEC mode. |
0x102 |
Router loads the Cisco IOS XR software with the console Break key disabled on the next system boot. Both 0x102 and 0x2102 specify the same functionality, as bit 13 in 0x2102 is not significant for Cisco IOS XR software. |
0x40 |
Router enters the password recovery mode on the next system boot. |
If you use the various keywords to set the configuration settings, note that the hexadecimal value is updated in an additive or subtractive manner to represent the keyword used. For example, if the current configuration setting is 0x102 and you use the config-register command with the password-recovery enable keywords, the value is updated to 0x142.
Task ID
Task ID |
Operations |
---|---|
root-lr |
read, write |
Examples
The following example shows how to set the configuration register on the DSC to 0x2. Setting the configuration registration to 0x2 causes the router to boot the Cisco IOS XR software and enter EXEC mode during a router reload.
RP/0/RSP0/CPU0:router(admin)# config-register boot-mode exec-mode
Sun May 31 12:10:36.037 PST Successfully set config-register to
0x2 on node 0/RSP0/CPU0