Cisco Systems 7500 Series manual Configuration Register Bit Meanings, Boot Field Meaning

Chapter 4 Performing a Basic Configuration of the System

Configuring the Software Configuration Register

2. OEM = original equipment manufacturer.

Table 4-2	Explanation of Boot Field (Configuration Register Bits 00 to 03)
Boot Field		Meaning
00		Stays at the system bootstrap prompt
01		Boots the first system image in onboard Flash memory
02 to 0F		Specifies a default network boot filename
		Enables boot system commands that override the default network boot filename

Configuration Register Bit Meanings

The lowest four bits of the software configuration register (bits 3, 2, 1, and 0) form the boot field. The boot field specifies a number in binary form. If you set the boot field value to 0, you must boot the operating system manually by entering the b command at the bootstrap prompt (>), as follows:

>b [tftp] flash filename

Definitions of the various b command options follow:

•b—Boots the default system software from Flash memory

•b flash—Boots the first file in onboard Flash memory

•b slot0: filename—Boots the file filename from the Flash memory card in PC Card slot 0

•b slot1: filename—Boots the file filename from the Flash memory card in PC Card slot 1

•b filename [host]—Boots from server host using TFTP

•b flash: [filename]—Boots the file filename from onboard Flash memory (abbreviated form of the boot system flash command shown below)

For more information about the b [tftp flash ] [filename] command, refer to the set of configuration fundamentals publications listed in the “If You Need More Configuration Information” section on page 4-32.

If you set the boot field value to 0x2 through 0xF and there is a valid boot system command stored in the configuration file, the router boots the system software as directed by that value. If there is no boot system command, the router forms a default boot filename for booting from a network server. (See Table 4-3for the format of these default filenames.)

In the following example, the software configuration register is set to boot the router from onboard Flash memory and to ignore the Break function at the next reboot of the router:

Router# conf term

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)# config-register 0x102

Router(config)# boot system flash [filename]

Crtl-Z

Router#

Table 4-3lists the default boot filenames or actions for the processor.

Note A boot system configuration command in the router configuration in NVRAM overrides the default filename created for booting over the network.

Cisco 7500 Series Installation and Configuration Guide

OL-5008-03 B0 4-5