80
OL-4923-01 B0
Changing Settings
To change the configuration register while running the system software, follow these steps:
Step 1
Enter the enable command and your password to enter privileged level, as follows:
Router> enable
Password:
Router#
Step 2
At the privileged-level system prompt (Router #), enter the configure terminal command. You are
prompted for further commands, as shown in the following example:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#
Step 3
To set the contents of the configuration register, enter the config-register 0xvalue configuration
command, where value is a hexadecimal number preceded by 0x (see
Table 19
), as in the following:
Router(config)# config-register 0x
value
Step 4
Exit the configuration mode by entering Ctrl-Z. The new value settings are saved to memory; however,
the new settings do not take effect until the system software is reloaded by rebooting the router.
Step 5
To display the configuration register value currently in effect and the value that will be used at the next
reload, enter the show version EXEC command. The value is displayed on the last line of the screen
display, as in the following example:
Configuration register is 0x141 (will be 0x101 at next reload)
Step 6
Reboot the router. The new value takes effect. Configuration register changes take effect only when the
system reloads, such as when you issue a reload command from the console.
This completes the procedure to change the configuration register while running the system software.
14
0x4000
IP broadcasts do not have network numbers
15
0x8000
Enable diagnostic messages and ignore NVRAM contents
1.
The factory default value for the configuration register is 0x0102. This value is a combination of the following: bit 8 =
0x0100 and bits 00 through 03 = 0x0001 (see
Table 19
).
2.
OEM = original equipment manufacturer
Table 19
Explanation of Boot Field (Software Configuration Register Bits 00 to 0F)
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
Table 18
Software Configuration Register Bit Meanings (Continued)
Bit Number
1
Hexadecimal
Meaning
