Datasheet

62
OL-17436-01
Additional Configuration and Maintenance Tasks
Bits in the Software Configuration Register
As described in the “Boot Field Settings” section on page 61, the boot field setting determines the source
of the Cisco IOS software image that is used to boot the router. A detailed description of the bit values
for the boot field and their associated action or filename is given in Table 20
The remaining bits in the software configuration register are described following:
Bit 8 of the software configuration register controls the console Break key. Setting bit 8 causes the
system to ignore the console Break key. This is the factory default. Conversely, clearing bit 8 causes the
system to interpret a Break keystroke as a command to halt normal system operation and force the system
Step 4
Router(config)# ctrl-Z
Exits global configuration mode.
Step 5
Router# show version
Displays the software configuration register value currently in
effect. This is the value that will be used the next time the router
reloads. The value is displayed on the last line of the display, as
in the following example:
Configuration register is 0x141 (will be 0x102 at next
reload)
Step 6
Router# copy running-config startup-config
or
Router# write memory
Saves the software configuration register settings to NVRAM.
Step 7
Router# reload
Reboots the router. Configuration register changes take effect
only after the system reloads.
Command Purpose
Table 20 Default Boot Filenames
Action/Filename Bit 3 Bit 2 Bit 1 Bit 0
Bootstrap mode 0 0 0 0
Default software 0 0 0 1
cisco2-grp or cisco2-prp 0 0 1 0
cisco3-grp or cisco3-prp 0 0 1 1
cisco4-grp or cisco4-prp 0 1 0 0
cisco5-grp or cisco5-prp 0 1 0 1
cisco6-grp or cisco6-prp 0 1 1 0
cisco7-grp or cisco7-prp 0 1 1 1
cisco10-grp or cisco10-prp 1 0 0 0
cisco11-grp or cisco11-prp 1 0 0 1
cisco12-grp or cisco12-prp 1 0 1 0
cisco13-grp or cisco13-prp 1 0 1 1
cisco14-grp or cisco14-prp 1 1 0 0
cisco15-grp or cisco15-prp 1 1 0 1
cisco16-grp or cisco16-prp 1 1 1 0
cisco17-grp or cisco17-prp 1 1 1 1