To upgrade to the copied IOS image after that image is saved on the router's flash memory, configure the router to load the new image during bootup using the boot system command. Save the configuration. Reload the router to boot the router with new image. After the router has booted, to verify the new image has loaded, use the show version command.

During startup, the bootstrap code parses the startup configuration file in NVRAM for the boot system commands that specify the name and location of the Cisco IOS Software image to load. Several boot system commands can be entered in sequence to provide a fault-tolerant boot plan.

Shown in Figure 1, the boot system command is a global configuration command that allows the user to specify the source for the Cisco IOS Software image to load. Some of the syntax options available include:

Router(config)# boot system flash0://c1900-universalk9-mz.SPA.152-4.M3.bin

Router(config)# boot system tftp://c1900-universalk9-mz.SPA.152-4.M3.bin

Router(config)# boot system rom

If there are no boot system commands in the configuration, the router defaults to loading the first valid Cisco IOS image in flash memory and running it.

As shown in Figure 2, the show version command can be used to verify the software image file.