Chap 7 IOS Images Andres, Wen-Yuan Liao Department of Computer Science and Engineering De Lin Institute of Technology

Overview Cisco IOS software source options Load IOS software onto the router Maintain backup files Upgrade IOS software The functions of the conf. register

The Basics of IOS Versions Locating the Cisco IOS software Configuration register values The show version command

Locating the Cisco IOS software The default source depends on the hardware platform The router looks to the boot system commands saved in NVRAM

NVRAM Configuration register: Boot field ROM moniter / ROM / Boot system command Router#config-register Boot system command Flash/TFTP/ROM Router(config)#boot system

Boot system Global configuration-mode boot system commands to enter fallback sources for the router to use in sequence

Configuration register values Configuration register:boot field Determine the order in which the router looks for system bootstrap information Router#config-register Change the default configuration register setting

The configuration register is a 16-bit register in NVRAM The lowest 4 bits bits 3,2,1,0: the boot field show version: verify the config-register command Configuration register values

(default)

The show version command Displays information about the Cisco IOS software version (system image) The configuration register and the boot field setting

Bootstrap Options in Software Boot system commands Preparing for the use of TFTP The show flash command

Preparing for the use of TFTP A TFTP server will allow image and conf. uploads and downloads over the network Another router or host system

The show flash command Verify that you have sufficient memory on your system for the Cisco IOS software Always backup your current IOS before upgrading to a newer version

IOS Naming and Software Image Backup Cisco's IOS naming conventions The copy flash tftp command The copy tftp flash command How to load a software image backup

Cisco's IOS naming conventions These images accommodate the various platforms, available memory resources, and feature set needs customers have for their network devices

The copy flash tftp command show flash command to learn the name of the system image file (xk09140z) copy flash tftp command to copy the system image to a TFTP server

The copy tftp flash command copy tftp flash Download the new image from the TFTP server Flash memory for more than a single Cisco IOS image

Exclamation point (!) : successfully transferred Vs: successful checksum verification

Summary Configuration commands in NVRAM The show version command IOS: Flash/TFTP server/ROM show flash Naming convention copy flash tftp/copy tftp flash