Command:

config-register


Mode:

Router(config)#


Syntax:

config-register register-value


Syntax Description:

register-value

Hexadecimal number or value that represents the 16-bit configuration register value that you want to use the next time the router is restarted. The value range is from 0x0 to 0xFFFF (0 to 65535 in decimal)

 

Command Description:

This command is used to define the configuration register. The register is a hexadecimal value from 0x0 to 0xFFFF. This command only applies to platforms which use a software configuration register. The lowest four bits of the configuration register (bits 3, 2, 1, and 0) form the boot field. The boot field determines if the router boots manually, from ROM, or from Flash, or from the network. To change the boot field value and leave all other bits set to their default values, follow these guidelines:


If you set the configuration register boot field value to 0x0, you must boot the operating system manually with the boot command.

If you set the configuration register boot field value to 0x1, the router boots using the default ROM software. If you set the configuration register boot field to any value from 0x2 to 0xF, the router uses the boot field value to form a default boot filename for booting from a network server. For more information about the configuration register bit settings and default filenames, see the appropriate router hardware installation guide.


Example:
    

The following sets the config register value to 0x2102 at next boot: 

Router(config)#config-register 0x2102


Misconceptions:

 

Unlike most commands, the changing of the config register does not occur until next boot. 


Related Commands:

 

show version

 

configure

 


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