3-31
Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 3 Configuring the Switch for the First Time Modifying the Supervisor Engine Startup Configuration

Flash Memory Features

Flash memory allows you to do the following:
Remotely load multiple system software images through TFTP or RCP transfers (one transfer for
each file loaded)
Boot a switch manually or automatically from a system software image stored in flash memory (you
can also boot directly from ROM)
Copy the system image to flash memory using TFTP
Boot the system from flash memory either automatically or manually
Copy the flash memory image to a network server using TFTP or RCP
For more information on flash memory, see this URL:
http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/hardware/configuration/notes/OL_2788.h
tml

Security Precautions

Note the following security precaution when loading from flash memory:
Caution You can only change the system image stored in flash memory from privileged EXEC level on the
console terminal.

Configuring Flash Memory

To configure your switch to boot from flash memory, perform the following procedure. Refer to the
appropriate hardware installation and maintenance publication for complete instructions on installing
the hardware.
Step 1 Copy a system image to flash memory using TFTP or other protocols. Refer to the “Cisco IOS File
Management” and “Loading and Maintaining System Images” chapters in the Cisco IOS Configuration
Fundamentals Configuration Guide, Release 12.2, at the following URL:
http://www.cisco.com/en/US/docs/ios/fundamentals/configuration/guide/12_2sr/cf_12_2sr_book.html
Step 2 Configure the system to boot automatically from the desired file in flash memory.
You might need to change the configuration register value. See the “Modifying the Boot Field and Using
the boot Command” section on page 3-27, for more information on modifying the configuration register.
Step 3 Save your configurations.
Step 4 Power cycle and reboot your system to verify that all is working as expected.
Controlling Environment Variables
Although the ROM monitor controls environment variables, you can create, modify, or view them with
certain commands. To create or modify the BOOT and BOOTLDR variables, use the boot system and
boot bootldr global configuration commands, respectively. Refer to the “Specify the Startup System