CCNA2

MODULE 5

MANAGING CISCO IOS

Determine how a Cisco device locates and loads the Cisco IOS Use the boot system command Identify the configuration register values Briefly describe the files used by the Cisco IOS and their functions List the locations on the router of the different file types Briefly describe the parts of the IOS name Save and restore configuration files using TFTP and copy-and-paste Load an IOS image using TFTP Load an IOS image using XModem Verify the file system using show commands

MANAGING CISCO IOS

Identify the stages of the router boot sequence

The startup routines must do the following:– Test the router hardware. – Find and load the Cisco IOS software. – Find and apply configuration statements,

including protocol functions and interface addresses

MANAGING CISCO IOS

MANAGING CISCO IOS

How a Cisco device locates and loads IOS – The default source for Cisco IOS software

depends on the hardware platform, but most commonly the router looks to the boot system commands saved in NVRAM

– Cisco IOS software allows several alternatives to be used. Other sources can be specified for the software, or the router can use its own fallback sequence to load the software

MANAGING CISCO IOS

MANAGING CISCO IOS

ROM – If flash memory is corrupted and the network server fails to load the image, booting from ROM is the final bootstrap option in software. However, the system image in ROM will likely be a subset of the Cisco IOS that lacks the protocols, features and configurations of the full Cisco IOS

MANAGING CISCO IOS

Troubleshooting IOS boot failure In the event that the router does not boot

properly, there are several things that could be wrong:

Configuration file has missing or incorrect boot system statement

Incorrect configuration register value Corrupted flash image Hardware failure

MANAGING CISCO IOS

When the router boots, it looks in the configuration file for a boot system statement. This boot system statement can force the router to boot from another image instead of the IOS in flash.

An incorrect configuration register setting will prevent the IOS from loading from flash

MANAGING CISCO IOS

The value in the configuration register tells the router where to get the IOS

This can be confirmed by using the show version command and looking at the last line for the configuration register

MANAGING CISCO IOS

MANAGING CISCO IOS

MANAGING CISCO IOS

MANAGING CISCO IOS

To identify the different versions, Cisco has a naming convention for IOS files. This IOS naming convention uses different fields in the name. Among the fields are the hardware platform identification, the feature set identification, and the numerical release

MANAGING CISCO IOS

MANAGING CISCO IOS

The first part of the Cisco IOS file name identifies the hardware platform for which this image is designed.

The second part of the IOS file name identifies the various features that this file contains. There are many different features to choose from. These features are packaged in "software images". Each feature set contains a specific subset of Cisco IOS features

MANAGING CISCO IOS

The third part of the file name indicates the file format. It specifies if the IOS is stored in flash in a compressed format and whether the IOS is relocatable

The fourth part of the file name identifies the release of the IOS. As Cisco develops newer versions of the IOS, the numerical version number increases.

MANAGING CISCO IOS

Managing configuration files using TFTP – Enter the command copy running-config tftp. – At the prompt, enter the IP address of the TFTP

server to store the configuration file. – Enter the name to assign to the configuration file

or accept the default name. – Confirm the choices by typing yes each time.

MANAGING CISCO IOS

MANAGING CISCO IOS

Enter the command copy tftp running-config. At the prompt, select a host or network configuration

file. At the system prompt, enter the IP address of the

TFTP server where the configuration file is located. At the system prompt, enter the name of the

configuration file or accept the default name. Confirm the configuration filename and the server

address that the system supplies.

MANAGING CISCO IOS

MANAGING CISCO IOS

Managing configuration files using copy and paste – Perform the following to capture the configuration

using the text displayed on the HyperTerminal screen to a text file

MANAGING CISCO IOS

Select Transfer Select Capture Text Specify the name for the text file to capture the configuration Select Start to start capturing text Display the configuration to the screen by entering show

running-config Press the space bar when each "-More -" prompt appears When the complete configuration has been displayed, stop

the capture by: Select Transfer Select Capture Text Select Stop

MANAGING CISCO IOS

MANAGING CISCO IOS

After the capture is complete, the configuration file needs to be edited to remove extra text. To create this in a form to be “pasted” back into the router, remove any unnecessary information from the captured configuration

MANAGING CISCO IOS

The configuration file can be edited from a text editor such as Notepad. To edit the file from Notepad click on File > Open. Find the captured file and select it. Click Open.

The lines that need to be deleted contain

MANAGING CISCO IOS

show running-config Building configuration... Current configuration: - More - Any lines that appear after the word "End"

MANAGING CISCO IOS

HyperTerminal can be used to restore a configuration. The clean backup of the configuration can be copied into the router.

MANAGING CISCO IOS

Enter router global configuration mode. From HyperTerminal, click on Transfer > Send Text File. Select the name of the file for the saved backup configuration. The lines of the file will be entered into the router as if they

were being typed. Observe any errors. After the configuration is entered, press Ctrl-Z key to exit global

configuration mode. Restore the startup configuration with copy running-config

startup-config.

MANAGING CISCO IOS

Managing IOS images using TFTP Occasionally the router will need to have the

IOS upgraded or restored This server should have a TFTP service

running. The IOS backup can be initiated from the privileged EXEC mode with the copy flash tftp command

MANAGING CISCO IOS

Managing IOS images using Xmodem If the IOS image in flash has been erased or

corrupted, the IOS may need to be restored from the ROM monitor mode (ROMmon).

In many of the Cisco hardware architectures, the ROMmon mode is identified from the rommon 1 > prompt.

MANAGING CISCO IOS

ROMMON Mode– When the Router starts showing “System

Bootstrap, Version … “ on the Hyper terminal screen, Press the CTRL key and the Break key together

– The Router will enter the Rommon mode– Rommon 1>

MANAGING CISCO IOS

If an image is located that appears to be valid, an attempt should be made to boot from that image. This is done using boot flash: command. For example if the image name was “c2600-is-mz.121-5”, the command would be:

rommon 1>boot flash:c2600-is-mz.121-5

MANAGING CISCO IOS

If the router will not properly boot from the image or there is no IOS image, a new IOS will need to be downloaded. The IOS file may be recovered using either Xmodem to restore the image through the console, or downloading the image using TFTP from the ROMmon mode.

MANAGING CISCO IOS

MANAGING CISCO IOS

MANAGING CISCO IOS