Cisco Systems OL-11497-03 manual Boot Field Settings

Chapter 4 Troubleshooting the Installation

Performing Other Configuration Tasks

Table 4-2	Boot Field and Meanings (continued)
Boot Field	Definition
02 to 0F	On power up, the system boots automatically from a default Cisco
	IOS software image stored on a TFTP server in the network. For
	this setting, it is assumed that the Ethernet port on the RP is
	configured and operational. This setting also enables boot system
	commands that override the default filename.

Note Note: A Cisco 12006 or Cisco 12406 Router is typically delivered from

the factory with a boot image in the boot flash and a Flash card containing a suitable working Cisco IOS image. If you need a Cisco IOS upgrade, you should FTP the appropriate Cisco IOS image from CCO.

Boot Field Settings

The four low-order bits of the software configuration register (bits 3, 2, 1, and 0) form a boot field that defines the source of a Cisco IOS software image for booting the router. You can set or change the contents of the boot field by issuing the config-registercommand at the global configuration mode prompt [router(config)#].

Note The factory default configuration register setting for an RP shipped in a router or an RP shipped as a field-replaceable unit is 0x0102.

When the boot field is set to either 0 or 1 (0000 or 0001), the system ignores any boot instructions in the system configuration file and one of the following occurs, depending on the boot field setting:

•When the boot field is set to 0, you must boot the operating system manually by entering the boot command at the ROM monitor prompt (rommon>). You can enter the boot command with or without arguments.

If you enter the boot command without an argument (that is, without specifying a file or any other boot instructions), the system automatically boots using the default image in the Flash memory SIMM on the RP.

	Cisco 12006 and Cisco 12406 Router Installation and Configuration Guide
4-4	OL-11497-03