Chapter 7 & 8 IOS Images and Router Configuration

Where’s the IOS? A method for specifying how the router loads the IOS, is by designating fallback sources for the router to use in sequence from NVRAM. By default, the router will first look in NVRAM Then it will look in Flash Then it will look towards the TFTP Server

Configuration Register Values Use the this command to change the default configuration register setting: Router(config)# config-register Set the configuration register value to 0x--0 (0x100) if you need to enter the ROM monitor. Set the configuration register value to 0x--1 (0x101) if you need to tell the router to boot from ROM. Set the configuration register value to 0x--2 (0x102) if you need to tell the router to boot from NVRAM.

Show Version Command The show version command displays information about the Cisco IOS software version that is currently running on the router. This includes the configuration register and the boot field setting . Show version displays information about the system file image. Show version is used to discover the configuration register setting.

TFTP Before copying software between the TFTP server or host and Flash memory, verify that there is sufficient room in Flash to accommodate the IOS. To copy a system image to a network server, use the Router# copy flash tftp command. If upgrading the IOS on a router, use the Router# copy tftp flash command to copy the new IOS image from a network server.

Show Flash Command Use the show flash command to verify that you have sufficient memory on your system for the Cisco IOS software that you want to load. Show flash is also used to view the name of the system image file.

Cisco’s IOS Naming Conventions The naming convention for Cisco IOS Release 11.2 contains three parts: the platform on which the image runs a letter or series of letters identifies the special capabilities and feature sets supported in the image specifics as to where the image runs and whether it has been zipped or compressed

Cisco’s IOS Naming Conventions In the Cisco IOS name cpa25-cg-1, the cpa25 represents the platform on which the image runs. In the Cisco IOS name cpa25-cg-1, the cg represents the special capabilities and feature sets.

Router Configuration Commands Router(config)# boot system flash IOS filename command is used to tell the router to boot from flash. Router(config)# boot system tftp IOS filename ip address command is used to tell the router to boot from a network server. Router(config)# boot system rom command is used to tell the router to boot from ROM. Router(config)# router rip command is used to configure a routing protocol.

Configuring an Interface Router(config-int)# int E0 ip address subnet mask command is used to configure a router’s Ethernet 0 port. Router(config-int)# int S0 ip address subnet mask command is used to configure a router’s Serial 0 port.

Password Recovery A common procedure that technicians perform on routers is the password recovery procedure. The configuration register 0x2142 is used on a Cisco 2500 series router during password recovery. (Why? And what does it mean??)

Summary Chapter 7 has great practical importance - students must know how to handle various IOS images. And several CCNA Certification Exam Objectives explicitly refer to the sources for loading an IOS image (flash, tftp server, ROM) and methods for backing-up, upgrading, and loading a backup Cisco IOS software image.

Summary Upon completing chapter 8, you should be able to configure a router with minimal information in a short amount of time. Make sure that you have entered the new IOS commands from chapters 7 & 8 into your Lab Companion!