Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

How to reset the booting option for Catalyst 4500 running Cisco IOS system software to the factory default settings

Core issue

The configuration register boot field determines whether the switch loads an  operating system image, as well as where it obtains this system image.

Note: The factory default configuration register setting for systems and spares is 0x0102.


To check the configuration register of the switch, issue the show bootvar command, as shown in this output:

4006-SUPIII#sh bootvar

BOOT variable = bootflash:cat4000-i5k91s-mz.122-20.EWA.bin,1

CONFIG_FILE variable does not exist

BOOTLDR variable =

Configuration register is 0x2102

To change the actual configuration register, refer to this output:

4006-SUPIII(config)#config-register ?

<0x0-0xFFFF>  Config register number

4006-SUPIII(config)#config-register 0x0102

To change the bootvar and boot from ldr use, refer to this output:

4006-SUPIII(config)#boot bootldr ?

bootflash: URL of the Boot helper image

slot0: URL of the Boot helper image

For more information, refer to Modifying the Boot Field and Using the boot Command section of Configuring the Switch for the First Time.