Configuration Register Bit Meanings - Cisco 7500 Series Configuration Manual

Chapter 4 Performing a Basic Configuration of the System
2. OEM = original equipment manufacturer.
Table 4-2
Boot Field
00
01
02 to 0F

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:
•
•
•
•
•
•
For more information about the b [tftp | flash ] [filename] command, refer to the set of configuration
fundamentals publications listed in the
page
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 4-3
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.
Router(config)# config-register 0x102
Router(config)# boot system flash [filename]
Crtl-Z
Router#
Table 4-3
Note A boot system configuration command in the router configuration in NVRAM overrides the default
filename created for booting over the network.
OL-5008-03 B0
Explanation of Boot Field (Configuration Register Bits 00 to 03)
Meaning
Stays at the system bootstrap prompt
Boots the first system image in onboard Flash memory
Specifies a default network boot filename
Enables boot system commands that override the default network boot filename
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)
4-32.
for the format of these default filenames.)
lists the default boot filenames or actions for the processor.
Configuring the Software Configuration Register
"If You Need More Configuration Information" section on
End with CNTL/Z.
Cisco 7500 Series Installation and Configuration Guide
4-5