3-18
Catalyst 2928 Switch Software Configuration Guide
OL-23389-01
Chapter 3 Assigning the Switch IP Address and Default Gateway
Modifying the Startup Configuration
Booting a Specific Software Image
By default, the switch attempts to automatically boot up the system using information in the BOOT
environment variable. If this variable is not set, the switch attempts to load and execute the first
executable image it can by performing a recursive, depth-first search throughout the flash file system. In
a depth-first search of a directory, each encountered subdirectory is completely searched before
continuing the search in the original directory. However, you can specify a specific image to boot up.
Beginning in privileged EXEC mode, follow these steps to configure the switch to boot a specific image
during the next boot cycle:
To return to the default setting, use the
no boot system
global configuration command.
Controlling Environment Variables
With a normally operating switch, you enter the boot loader mode only through a switch console
connection configured for 9600 b/s. Unplug the switch power cord, and press the switch
Mode
button
while reconnecting the power cord. You can release the
Mode
button a second or two after the LED
above port 1 turns off. Then the boot loader
switch:
prompt appears.
The switch boot loader software provides support for nonvolatile environment variables, which can be
used to control how the boot loader, or any other software running on the system, behaves. Boot loader
environment variables are similar to environment variables that can be set on UNIX or DOS systems.
Environment variables that have values are stored in flash memory outside of the flash file system.
Each line in these files contains an environment variable name and an equal sign followed by the value
of the variable. A variable has no value if it is not listed in this file; it has a value if it is listed in the file
even if the value is a null string. A variable that is set to a null string (for example, “ ”) is a variable with
a value. Many environment variables are predefined and have default values.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
boot system
filesystem
:/
file-url
Configure the switch to boot a specific image in flash memory during the
next boot cycle.
•
For
filesystem
:
, use
flash:
for the system board flash device.
•
For
file-url
, specify the path (directory) and the name of the bootable
image.
Filenames and directory names are case sensitive.
Step 3
end
Return to privileged EXEC mode.
Step 4
show boot
Verify your entries.
The
boot system
global command changes the setting of the BOOT
environment variable.
During the next boot cycle, the switch attempts to automatically boot up the
system using information in the BOOT environment variable.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
