Cisco Systems CISCO7201 Bits, Boot Field Meaning, Boots the boot helper image as a system image

Appendix C Configuration Register Information

Configuration Bit Meanings

Table C-1	Configuration Register Bit Settings (continued)
Bit No.	Hex	Meaning
11–12	0x800–0x1000	Console line speed
13	0x2000	Boots default ROM software if initial boot fails
14	0x4000	IP broadcasts do not have network numbers
15	0x8000	Enables diagnostic messages and ignores NVRAM contents

Bits 0–3

The lowest four bits of the processor configuration register (bits 3, 2, 1, and 0) form the boot field. Table C-2provides information about the bits settings.

Table C-2	Bits 0–3 Settings
Boot Field	Meaning
0	Stays at the system bootstrap prompt (ROM monitor) on a reload or power cycle
1	Boots the boot helper image as a system image
2	Full boot process, which loads the Cisco IOS image into flash memory
2-F	Specifies a default filename for booting over the network from a TFTP server

The boot field specifies a number in binary. If you set the boot field value to 0, you must have a console port access to boot the operating system manually. Boot the operating system by entering the b command at the bootstrap prompt as follows:

> b [tftp] flash filename

Definitions of the various command options follow:

b—Boots the default system software from ROM

b flash—Boots the first file in flash memory

bfilename [host]—Boots over the network using TFTP

bflash filename—Boots the file (filename) from flash memory

If you set the boot field value to a value of 2 through F, and there is a valid system boot command stored in the configuration file, the router boots the system software as directed by that value. (See Table C-3.) If you set the boot field to any other bit pattern, the router uses the resulting number to form a default boot filename for netbooting.

If there are no boot commands in the configuration file, the router attempts to boot the first file in system flash memory. If no file is found in system flash memory, the router attempts to netboot a default file with a name derived from the value of the boot field (for example, cisco2-7201). If the netboot attempt fails, the boot helper image in boot flash memory will boot up.

If boot commands are in the configuration file, the router software processes each boot command in sequence until the process is successful or the end of the list is reached. If the end of the list is reached without a file being successfully booted, the router will retry the netboot commands up to six times if bit 13 of the configuration register is set, otherwise it will load the operating system software available

Cisco 7201 Installation and Configuration Guide

C-2 OL-11364-04