CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 69 pdf

Locating and Loading Cisco IOS Software 649Conﬁguration Register Values The order in which the router looks for Cisco IOS Software images to load depends on the boot ﬁeld setting in the

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Locating and Loading Cisco IOS Software 649

Conﬁguration Register Values

The order in which the router looks for Cisco IOS Software images to load depends on

the boot ﬁeld setting in the conﬁguration register You can change the default

configu-ration register setting with the global configuconfigu-ration command config-register Use a

hexadecimal number as the argument for this command, as shown in Example 14-4

The conﬁguration register is set so that the router examines the startup ﬁle in NVRAM

for boot system options The conﬁguration register is a 16-bit register in NVRAM The

lowest 4 bits of the conﬁguration register (bits 3, 2, 1, and 0) form the boot ﬁeld To

change the boot ﬁeld and leave all other bits set at their original values, follow these

guidelines:

■ Set the conﬁguration register value to 0x100 if the ROM monitor needs to be

entered This setting is primarily a programmer’s environment Boot the

operat-ing system manually from the ROM monitor Use the b command at the ROM

monitor prompt to boot the system This value sets the boot ﬁeld bits to 0-0-0-0

■ Set the conﬁguration register to 0x101 to conﬁgure the system to boot

automati-cally from the limited Cisco IOS Software image in ROM This value sets the boot ﬁeld bits to 0-0-0-1

Example 14-3 Booting from ROM

Router# configure terminal

Router#(config)# boot system rom

[Ctrl-Z]

Router# copy running-config startup-config

Lab Activity Using the boot system Command

In this activity, you gather information about the Cisco IOS Image and deter-mine its boot source You also check the conﬁg register settings and document

a fallback boot sequence

Example 14-4 Chaging the Boot Field Setting in the Conﬁguration Register

Router# configure terminal

Router(config)# config-register 0x10F

[Ctrl – Z]

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650 Chapter 14: Managing Cisco IOS Software

■ Set the conﬁguration register to any value from 0x102 to 0x10F to conﬁgure the system to use the boot system commands in NVRAM This setting is the default

These values set the boot ﬁeld bits to 0-0-1-0 through 1-1-1-1

If there are no boot system commands in NVRAM, the system will typically look to Flash memory for the Cisco IOS Software image

Table 14-1 shows the boot ﬁeld values in the conﬁguration register

To check the boot ﬁeld setting and to verify the conﬁg-register command, use the show version command.

Displaying the Currently Running Cisco IOS Software Version

The show version command, as shown in Example 14-5, displays information about

the Cisco IOS Software version that is currently running on the router This version information includes the conﬁguration register and the boot ﬁeld setting

Table 14-1 Boot Field Values in the Conﬁguration Register

using the b command).

router has no Flash memory)

(0x102 is the default if the router has Flash memory)

Lab Activity Troubleshooting Conﬁg Register Boot Problems

In this activity, you check and document the conﬁguration register settings related to boot method and conﬁgure the router to boot from Flash

Example 14-5 Conﬁguration Register

cisco Systems, Inc Compiled Wed 25-Oct-00 05:18 by cmong Image text-base:

0x03071DB0, data-base: 0x00001000

2500 Software (C2500-JS-L),

chpt_14.fm Page 650 Tuesday, May 27, 2003 2:16 PM

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Managing Cisco IOS Software Images 651

In the example, the Cisco IOS Software version and descriptive information are

highlighted on the second line of output The screen captured shows Software

Release 12.1(5)

The next highlighted portion of the output shows the system image ﬁle is c2500-js-l,

booted using Flash Notice the portion of the ﬁlename that indicates that this image is

for a Cisco 2500 platform

As the output of the show version command continues, information is displayed about

the type of platform on which the version of Cisco IOS Software is currently running

The ﬁnal highlighted output provides the targeted results of the

command—config-register 0x2142 This information is used to enter configuration command—config-register values.

Managing Cisco IOS Software Images

Routers and switches depend on software for their operation The two types of software

required are operating systems and conﬁguration

The operating system used in almost all Cisco devices is the Cisco Internetwork

Operating System (IOS) Cisco IOS Software allows the hardware to function as a

router or switch The Cisco IOS Software ﬁle is several megabytes in size Cisco IOS

Software is the platform that ensures that the network provides the connectivity,

reli-ability, security, quality of service, scalreli-ability, and management capabilities required

for applications

ROM: System Bootstrap, Version 5.2(8a), RELEASE SOFTWARE BOOTFLASH:

3000 Bootstrap Software (IGS-RXBOOT), Version 10.2(8a), RELEASE SOFTWARE (fc1)

Router uptime is 7 minutes System returned to ROM by reload System image file

is "flash:c2500-js-l_121-5.bin"

cisco 2500 (68030) processor (revision D) with 16384K/2048K bytes of memory

Processor board ID 03867477, with hardware revision 00000000 Bridging software

Meridian Technology Corp) TN3270 Emulation software 1 Token Ring/IEEE 802.5

interface(s) 2 Serial network interface(s) 32K bytes of non-volatile

configuration memory 16384K bytes of processor board System flash (Read ONLY)

Configuration register is 0x2142

Example 14-5 Conﬁguration Register (Continued)

"flash:c2500-js-l_121-5.bin"

NOTE

There is no evidence

of any conﬁg-register setting in output

from either the show

running-conﬁg or show startup-conﬁg

command.

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The software a router or switch uses is referred to as the configuration file or the config.

The configuration file contains the instructions that define how the device is to route

or switch A network administrator creates a configuration file that defines the desired functions of the Cisco device Examples of the functions that can be specified by the config are the IP addresses of the interfaces, routing protocols, and networks to be advertised The configuration file typically is a few hundred to a few thousand bytes

in size

Each of the software components is stored in memory as a separate ﬁle These ﬁles are also stored in different types of memory

The Cisco IOS Software image is stored in a memory area called Flash Flash memory provides nonvolatile storage of a Cisco IOS Software image that can be used as an operating system at startup Flash allows you to upgrade Cisco IOS Software or to store multiple Cisco IOS Software ﬁles In many router architectures, the Cisco IOS Software image is copied from Flash and run from random-access memory (RAM)

A copy of the configuration file is stored in NVRAM to be used as a configuration

during startup This NVRAM conﬁguration is referred to as the startup conﬁg The

startup config is copied into RAM at boot time This configuration in RAM is the configuration used to operate the router The RAM configuration is referred to as the

running conﬁg.

A single interface to all the file systems that a router uses is provided in Software Release 12 of Cisco IOS Software This version is referred to as the Cisco IOS File System (IFS) The IFS provides a single method to perform all the file system manage-ment that a router uses This IFS includes the Flash memory file systems, the network file systems, and reading or writing data The network file systems include TFTP, remote copy protocol (RCP), and File Transfer Protocol (FTP) The reading or writing data includes NVRAM, the running configuration, and ROM The IFS uses a common set

of preﬁxes to specify ﬁle system devices Table 14-2 provides an overview of the IFS

Table 14-2 IOS File System

platforms For platforms that do not have a device named Flash, the preﬁx ﬂash: is aliased

to slot0: Therefore, the preﬁx ﬂash: can be used to refer to the main Flash memory stor-age area on all platforms

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The IFS uses the Universal Resource Locator (URL) convention to specify ﬁles on

network devices and the network The URL convention identiﬁes the location of the

configuration files following the colon as [[[//location]/directory]/filename] The IFS

also supports FTP ﬁle transfer Table 14-3 lists the commands used to manage Cisco

IOS Software for Software Release 12.0 and compares them against counterpart

com-mands used in Cisco IOS Software releases prior to 12.0

Industry Association (PCMCIA) Flash memory card

running conﬁguration

Table 14-3 Commands for Managing Cisco IOS Software Release 12.0 and Earlier

Pre Cisco IOS Software Release 12.0 Commands

Cisco IOS Software Release 12.x Commands

conﬁgure network (pre-Cisco IOS Software

Release 10.3)

copy rcp running-conﬁg

copy tftp running-conﬁg

copy ftp: system:running-config copy rcp: system:running-config copy tftp: system:running-config

continues

Table 14-2 IOS File System (Continued)

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Cisco IOS Software Naming Conventions

Cisco develops many different versions of Cisco IOS Software Cisco IOS Software supports varied hardware platforms and features Cisco continuously develops and releases new versions of Cisco IOS Software

Cisco has a naming convention for Cisco IOS Software ﬁles to identify the different versions of these Cisco IOS Software ﬁles, as illustrated by Figure 14-3

conﬁgure overwrite-network

(pre-Cisco IOS Software Release 10.3)

copy rcp startup-conﬁg copy tftp startup-conﬁg

copy ftp: nvram:startup-config copy rcp: nvram:startup-config copy tftp: nvram:startup-config

show conﬁguration

show startup-conﬁg

more nvram:startup-conﬁg

write erase

erase startup-conﬁg

erase nvram:

write memory

copy running-conﬁg startup-conﬁg

copy system:running-conﬁg nvram:startup-conﬁg

write network

copy running-conﬁg rcp copy running-conﬁg tftp

copy system:running-config ftp: copy system:running-config rcp: copy system:running-config tftp

write terminal

show running-conﬁg

more system:running-conﬁg

Table 14-3 Commands for Managing Cisco IOS Software Release 12.0 and Earlier (Continued)

Pre Cisco IOS Software Release 12.0 Commands

Cisco IOS Software Release 12.x Commands

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Figure 14-3 Cisco IOS Software Naming Conventions

As Figure 14-3 shows, this Cisco IOS Software naming convention uses different ﬁelds

in the name:

■ Hardware Platform—The first part of the filename identifies the hardware

plat-form This image is designed for the hardware platplat-form

■ Feature Set—The second part of the ﬁlename identiﬁes the various features that

the Cisco IOS Software ﬁle contains You can choose from many different features, and these features are packaged in “software images.” Each feature set contains

a speciﬁc subset of Cisco IOS Software features Examples of the feature set cate-gories are as follows:

— Basic—Basic is a basic feature set for the hardware platform Examples

of Basic are IP and IP/FW

— Plus—Plus is a basic feature set plus additional features such as IP Plus,

IP/FW Plus, and Enterprise Plus

— Encryption—Encryption has the 56-bit data encryption feature sets added

to either a Basic or Plus feature set Examples include IP/ATM PLUS IPSEC

56 or Enterprise Plus 56 The encryption designators are k8/k9 starting with the Cisco IOS Software Release 12.2 k8 is less than or equal to 64-bit encryption on Release 12.2 and up k9 is greater than 64-bit encryption on Release 12.2 and up

■ File Format—The third part of the IOS ﬁlename indicates the ﬁle format The

third part speciﬁes if Cisco IOS Software is stored in Flash memory in a com-pressed format and if the Cisco IOS Software image is relocatable If the Flash image is compressed, Cisco IOS Software must be expanded during boot as the image is copied to RAM A relocatable image is copied from Flash memory into RAM to run A non-relocatable image is run directly from Flash memory

c2600-js-l_121-3.bin

Version and Release Numbers (Version 12.1 Release 3) File Format (Relocatable; Not Compressed) Feature Set (Enterprise with Extended Capabilities) Hardware Platform (2600)

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■ Version and Release—The fourth part of the IOS ﬁlename identiﬁes the version

number and release of Cisco IOS Software As Cisco develops newer versions of Cisco IOS Software, the numerical version number increases

Managing Conﬁguration File Using TFTP

In a Cisco router or switch, the active configuration is in RAM The default location for the startup configuration in a Cisco router or switch is NVRAM In the event the configuration is lost, you should back up this startup configuration You can store one

of these backup copies of the configuration on a TFTP server You can use the copy running-config tftp command to back up the configuration The steps to perform this

backup process are as follows:

Step 1 Enter copy tftp running-conﬁg.

Step 2 Enter the IP address of the TFTP server that is to store the conﬁguration

ﬁle at the prompt

Step 3 Enter the name to assign to the conﬁguration ﬁle or accept the default

name

Step 4 Conﬁrm the choices by typing yes each time.

Example 14-6 demonstrates the actual process

You can restore the router configuration by loading the backup configuration file from

a TFTP server The steps you can take to restore the conﬁguration are as follows:

Step 1 Enter copy tftp running-conﬁg.

Step 2 Select a host or network conﬁguration ﬁle at the prompt

Step 3 At the system prompt, enter the IP address of the TFTP server where the

conﬁguration ﬁle is located

Step 4 At the system prompt, enter the name of the conﬁguration ﬁle or accept

the default name

Step 5 Confirm the configuration filename and the server address that the system

supplies

Example 14-6 Backing Up the Startup Conﬁguration on a TFTP Server

Cougar# copy running-config tftp Address or name of remote host [] 192.168.119.20 Destination file name [Cougar-config]?

!!!!!!!!!!!!!!!!!!!!!!!!

624 bytes copied in 7.05 secs Cougar#

NOTE

If the router conﬁg

ﬁle is missing or if the

erase startup-conﬁg

and reload commands

have been used, the

router will not have

any interfaces

conﬁg-ured TFTP requires

IP to make a

connec-tion, so you will need

to connect to the

router using the

con-sole port and

conﬁg-ure an IP address for

the interface that will

provide access to the

TFTP server.

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Example 14-7 demonstrates the process of restoring the conﬁguration from a TFTP

server

To copy the conﬁguration ﬁle from the TFTP server back to the router, perform the

fol-lowing steps:

Step 1 Enter conﬁguration mode by entering the copy tftp running-conﬁg

command

Step 2 At the system prompt, select a host or network conﬁguration ﬁle The

network configuration file contains commands that apply to all routers and terminal servers on the network The host configuration file contains commands that apply to one router in particular At the system prompt, enter the optional IP address of the remote host where the configuration file is located In Example 14-8, the router is configured from the TFTP server at IP address 131.108.2.155

Step 3 At the system prompt, enter the name of the conﬁguration ﬁle or accept

the default name The ﬁlename convention is UNIX-based The default

filename is hostname -config for the host file and network -config for the

network configuration file In the DOS environment, the server filenames are limited to eight characters plus a three-character extension An

example is router.cfg Confirm the configuration filename and the server

address that the system supplies Notice in Example 14-8 that the router

prompt changes to tokyo immediately This change is evidence that the

reconﬁguration happens as soon as the new ﬁle is downloaded

Example 14-7 Restoring the Startup Conﬁguration from a TFTP Server

Cougar# copy tftp running-config

Address or name of remote host [] 192.168.119.20

Source filename []? Cougar-confg

Destination filename [running-config]?

Accessing tftp://192.168.119.20/GAD-confg…

Loading GAD-confg from 192.168.119.20

(via FastEthernet 0/0): !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[OK-624 bytes]

624 bytes copied in 9.45 secs Cougar#

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Example 14-8 demonstrates the process of copying the conﬁguration ﬁle from a TFTP server

Managing Conﬁguration Files with HyperTerminal

Capturing the output of the show running-conﬁg command is another way to create a

backup copy of the configuration You can perform this backup from the terminal ses-sion by copying the output, pasting to a text file, and saving the text file However, this file needs some editing done before you can use it to restore configuration to the router Figure 14-4 shows an example of cutting and pasting configurations

To capture the conﬁguration in HyperTerminal text that is displayed on the screen to a text ﬁle, use the following steps:

Step 1 Select Transfer.

Step 2 Select Capture Text.

Step 3 Specify the name for the text ﬁle to the capture conﬁguration

Step 4 Select Start to start capturing text.

Step 5 Display the conﬁguration to the screen by entering show running-conﬁg Step 6 Press the space bar when each “-More -” prompt appears, which

contin-ues with the conﬁguration until the end is reached

Step 7 When the complete conﬁguration has been displayed, stop the capture

using the following steps:

a Select Transfer.

b Select Capture Text.

c Select Stop.

Example 14-8 Copying the Conﬁguration File from a TFTP Server

tokyo# copy tftp running-config Host or network configuration file [host]?

IP address of remote host [255.255.255.255]? 131.108.2.155 Name of configuration file [Router-config]? tokyo.2 Configure using tokyo.2 from 131.108.2.155? [confirm] y Booting tokyo.2 from 131.108.2.155:!! [OK-874/16000 bytes]

tokyo#

Lab Activity Managing Conﬁguration Files with TFTP

In this activity, you copy a router configuration file to a TFTP server and then configure the router by copying the file back from the TFTP server

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