Module Overview
16.1 Router Boot
Sequence and Verification
16.1.1 Stages of
the router power-on boot sequence
16.1.2 How a Cisco
device locates and loads IOS
16.1.3 Using the
boot system command
16.1.4
Configuration register
16.1.5
Troubleshooting IOS boot failure
16.2 Managing the
Cisco File System
16.2.1 IOS file
system overview
16.2.2 The IOS
naming convention
16.2.3 Managing
configuration files using TFTP
16.2.4 Managing
configuration files using copy and paste
16.2.5 Managing
IOS images using TFTP
16.2.6 Managing
IOS images using Xmodem
16.2.7 Environment
variables
16.2.8 File system
verification
Module: Summary
Overview
This page
summarizes the topics discussed in this module.
A Cisco router
cannot operate without the Cisco IOS. Each Cisco router has a predetermined
boot-up sequence that is used to locate and load the Cisco IOS. This module
will describe the stages and importance of this bootup procedure.
Cisco internetworking
devices use several different files to operate, such as Cisco IOS images and
configuration files. A network administrator must manage these files to ensure
that the proper versions are used and that necessary backups are performed.
This module also describes the Cisco file system and provides the tools to
manage it effectively.
This module
covers some of the objectives for the CCNA 640-801, INTRO 640-821, and ICND
640-811 exams. -
Students who
complete this module should be able to perform the following tasks:
- Identify the stages of the
router boot sequence
- 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 of the
different file types on a router
- Briefly describe the parts of
the IOS name
- Use TFTP and copy-and-paste to
save and restore configuration files
- Use TFTP to load an IOS image
- Use XModem to load an IOS image
- Use show commands to verify the
file system
16.1
Router Boot Sequence and Verification
16.1.1
Stages of the router power-on boot sequence
This page will
describe the router startup sequence.
The goal of the
startup routines for Cisco IOS software is to start the router operations. A
router must reliably connect any configured networks. To do this, the startup
routines must do the following:
- Test the router hardware
- Find and load the Cisco IOS
software
- Find and apply configuration
statements such as protocol functions and interface addresses
Figure illustrates the sequence and services that
are used to initialize a router.
Students can use
the Interactive Media Activity to test their familiarity with the router boot
sequence.
The next page
will describe how a Cisco device finds and loads Cisco IOS.
16.1
Router Boot Sequence and Verification
16.1.2
How a Cisco device locates and loads IOS
The page will
explain how a Cisco device finds and loads Cisco IOS.
The default source
for Cisco IOS software depends on the hardware platform. Most routers use 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.
The settings in
the configuration register enable the following alternatives:
- Global configuration mode boot
system commands can be specified to enter fallback sources for a router to
use in sequence. The router will use these commands as needed when it
restarts.
- If NVRAM lacks boot system
commands that a router can use, the system will use the Cisco IOS software
in flash memory by default.
- If flash memory is empty, a
router will try to use TFTP to load an IOS image from the network. The
router will use the configuration register value to form a filename from
which to boot a default system image that is stored on a network server.
- If a TFTP server is
unavailable, the router will load the limited version Cisco IOS software
image stored in ROM.
The Interactive
Media Activity will help students become familiar with the process a Cisco
device uses to find and load IOS.
The next page
will explain how boot system commands are used.
16.1
Router Boot Sequence and Verification
16.1.3
Using the boot system command
This page will
explain how boot system commands are used to specify the fallback boot-up
sequence for Cisco IOS software.
The three figures
show boot system entries. These entries specify that a Cisco IOS software image
will load first from flash memory, then from a network server, and finally from
ROM:
- Flash memory
- A system image can be loaded from flash memory. Information stored in
flash memory is not vulnerable to network failures that can occur when
system images are loaded from TFTP servers.
- Network server
- If flash memory is corrupted, a system image can be loaded from a TFTP
server.
- ROM
- The final bootstrap option is to boot from ROM. However, a system image
in ROM is usually a subset of the Cisco IOS that lacks the protocols,
features, and configurations of the full Cisco IOS. Also, if the software
has been updated, a router may have an older version stored in ROM.
The command copy
running-config startup-config saves the commands in NVRAM. The router will
execute the boot system commands as needed in the order in which they were
originally entered into configuration mode.
In the Lab
Activities, students will use boot system commands to display information about
the Cisco IOS image and boot procedure of a router.
The next page
will describe the router configuration register.
16.1
Router Boot Sequence and Verification
16.1.4
Configuration register
This page will
explain how a router uses the configuration register. Students will also learn
how to change the boot field.
The order in
which the router looks for system bootstrap information depends on the boot
field setting in the configuration register. The default configuration register
setting can be changed with the global configuration mode command
config-register. Use a hexadecimal number as the argument for this command.
The configuration
register is a 16-bit register in NVRAM that is represented as 4 hexadecimal
digits. The lowest four bits of the configuration register form the boot field.
To ensure that the upper 12 bits are not changed, first use the show version
command to retrieve the current values of the configuration register. Then use the config-register command and change
only the value of the last hexadecimal digit.
To change the
boot field in the configuration register, follow these guidelines:
- To enter the ROM monitor mode,
set the configuration register value to 0xnnn0, where nnn represents the
previous value of the non-boot field digits. This value sets the boot
field bits to 0000 binary. After a reload or power cycle, the device will
boot to ROM monitor prompt. Use the b command to boot the operating system
manually.
- To boot from the first image in
Flash or to boot to the IOS in ROM (platform dependant), set the
configuration register to 0xnnn1, where nnn represents the previous value
of the non-boot field digits. This value sets the boot field bits to 0001
binary. Older platforms, such as Cisco 1600 and 2500 routers, will boot to
a limited IOS in ROM. Newer platforms, such as Cisco 1700, 2600 and high
end routers, will boot from the first image in Flash.
- To configure the system to use
the boot system commands in NVRAM, set the configuration register to any
value from 0xnnn2 to 0xnnnF, where nnn represents the previous value of
the non-boot field digits. These values set the boot field bits to a value
between 0010 and 1111 binary. The router sequentially processes each boot
system command in NVRAM until the process is successful or the end of the
list is reached. If there are no boot system commands in the startup
configuration file, the router attempts to boot the first file in flash
memory.
The Lab Activity
will require students to change the boot process of a router.
The next page
will teach students how to troubleshoot IOS boot failures.
16.1
Router Boot Sequence and Verification
16.1.5
Troubleshooting IOS boot failure
This page will
explain why a router may not boot properly and show students what to do when
this occurs.
There are several
reasons that a router may not boot properly:
- Configuration file has missing
or incorrect boot system statement
- Incorrect configuration
register value
- Corrupted flash image
- Hardware failure
When a router
boots, it looks in the startup 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. Use the show version command to look for the line
that identifies the boot image source.
Use the show
running-config command and look for a boot system statement near the top of the
configuration. If the boot system statement points to an incorrect IOS image,
use the no version of the command to delete the statement.
If the
configuration register setting is incorrect, the IOS cannot load from flash.
The value in the configuration register tells the router where to get the IOS.
To confirm this, use the show version command and look at the last line for the
configuration register. The correct value varies for different hardware
platforms. A part of the documentation of the internetwork should be a printed
copy of the show version output. If that documentation is not available, there
are resources on the Cisco documentation CD or Cisco website to identify the
correct configuration register value. To correct this, change the configuration
register and save this as the start-up configuration.
If there is still
a problem, the router may have a corrupted flash image file. If this is the
case, an error message should be displayed during boot. That message may take
one of several forms. Some examples are as follows:
- open: read error...requested
0x4 bytes, got 0x0
- trouble reading device magic
number
- boot: cannot open
"flash:"
- boot: cannot determine first
file name on device "flash:"
If the flash
image is corrupt, a new IOS should be uploaded into the router.
If none of the
above appears to be the problem, the router could have a hardware failure. If
this occurs, contact the Cisco Technical Assistance Center (TAC). Although
hardware failures are rare, they do occur.
The value of the
configuration register is not displayed by the show running-config or show
startup-config commands.
Students can use
the Lab Activities to troubleshoot IOS boot failure and document configuration
register settings.
This page
concludes this lesson. The next lesson will show students how to manage the
Cisco IOS File System. The first page will give an overview of the IOS File
System.
16.2
Managing the Cisco File System
16.2.1
IOS file system overview
This page will
introduce the Cisco IOS File System.
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 IOS. The Cisco IOS is the
software that allows the hardware to function as a router or switch. The IOS
file is several megabytes.
The software a
router or switch uses is referred to as the configuration file or the config.
The configuration contains the instructions that define how the device is to
route or switch. A network administrator creates a configuration that defines
the desired functionality of a Cisco device. The functions that can be
specified by the configuration 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.
Each of the
software components is stored in memory as a separate file. These files are
also stored in different types of memory.
The IOS is stored
in a memory area called flash. Flash memory provides non-volatile storage of an
IOS that can be used as an operating system at startup. The flash allows the
IOS to be upgraded or stores multiple IOS files. In many router architectures,
the IOS is copied into and run from RAM.
A copy of the
configuration file is stored in NVRAM to be used during startup. This is
referred to as the startup configuration or startup config. The configuration
in RAM is used to operate a router. It is referred to as the running
configuration or running config.
Version 12 and
later releases of the IOS provide a single interface to all the file systems
that a router uses. This is referred to as the Cisco IOS File System (IFS). The
IFS provides a single method to perform all the file system management for a
router. This includes the flash memory file systems, the network file systems,
such as TFTP and FTP, and read or write data, such as NVRAM, the running
configuration, and ROM. The IFS uses a common set of prefixes to specify file
system devices.
The IFS uses the
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 transfers.
The Interactive
Media Activity will help students become familiar with the IFS configuration
files and their locations.
The next page
will describe the IOS naming conventions.
16.2
Managing the Cisco File System
16.2.2
The IOS naming convention
This page will
introduce the Cisco IOS naming convention. Students will learn why it is used
and what each field represents.
There are many
different versions of the Cisco IOS. The IOS supports varied hardware platforms
and features. New versions of the IOS are continuously developed and released.
To identify the
different versions, there is a naming convention for IOS files. This IOS naming
convention uses different fields in the name. The fields include the hardware
platform identification, the feature set identification, and the numerical
release.
The first part of
the Cisco IOS file name identifies the hardware platform for which an image is
designed.
The second part of
the IOS file name identifies the various features that a 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. Here are some examples of feature-set categories:
- Basic
- A basic feature set for a hardware platform such as IP and IP/FW
- Plus
- A basic feature set plus additional features such as IP Plus, IP/FW
Plus, and Enterprise Plus
- Encryption
- A 56-bit data encryption feature set, such as Plus 56, that is combined
with a basic or plus feature set. Examples include IP/ATM PLUS IPSEC 56 or
Enterprise Plus 56.
The encryption
designators for Cisco IOS Release 12.2 or later are k8 and k9:
—k8 - Less than
or equal to 64-bit encryption in IOS version 12.2 and later
—k9 - Greater
than 64-bit encryption in IOS version 12.2 and later
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. If the flash
image is compressed, the IOS must be expanded during boot as it is copied to
RAM. A relocatable image is copied from flash into RAM to run. A
non-relocatable image is run directly from flash.
The fourth part
of the file name identifies the release of the IOS. The numerical version
number increases for newer versions of the IOS.
The Interactive
Media Activity will help students become familiar with the fields in an IOS
image name.
The next page
will show students how a TFTP server can be used to manage configuration files.
16.2
Managing the Cisco File System
16.2.3
Managing configuration files using TFTP
This page will
explain how a TFTP server can be used to back up the configuration files for a
Cisco device.
In a Cisco router
or switch, the active configuration is in RAM and the default location for the
startup configuration is NVRAM. The startup configuration should be backed up
in case the configuration is lost. One of these backup copies of the
configuration can be stored on a TFTP server. The copy running-config tftp
command can be used to do this. The
steps for this process are listed below:
- Enter the command copy
running-config tftp.
- 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.
- Type yes to confirm each
choice.
The backup
configuration file can be loaded from a TFTP server to restore the router
configuration. The steps below outline
this process:
- Enter the command copy tftp
running-config.
- Select a host or network
configuration file at the prompt.
- Enter the IP address of the
TFTP server where the configuration file is located.
- Enter the name of the
configuration file or accept the default name.
- Confirm the configuration
filename and the server address that the system supplies.
The Lab Activity on this page
will teach students how to back up a copy of a router configuration file and
load it from a TFTP file server.
The next page
will show students how the copy and paste feature can be used to manage
configuration files.
16.2
Managing the Cisco File System
16.2.4
Managing configuration files using copy and paste
This page will
explain how HyperTerminal can be used to copy a configuration. The file is then
edited and pasted back into the router.
Another way to
create a backup copy of the configuration is to capture the output of the show
running-config command. To do this from the terminal session, copy the output,
paste it into a text file, and then save the text file. This file will need to
be edited before it can be used to restore the router configuration.
Perform the
following steps to capture the configuration from a HyperTerminal screen:
- Select Transfer.
- Select Capture Text.
- Specify a name for the text
file to capture the configuration.
- Select Start to start capturing
text.
- Use the show running-config
command to display the configuration on the screen.
- Press the Spacebar when each
"-More -" prompt appears.
After the
complete configuration has been displayed, use the following steps to stop the
capture:
- Select Transfer.
- Select Capture Text.
- Select Stop.
After the capture
is complete, the configuration file needs to be edited to remove extra text.
Remove any unnecessary information from the captured configuration so it can be
pasted back into the router. Comments may also be added to explain the various
parts of the configuration. To add a comment, begin a line with an exclamation
mark (!).
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 the following information:
- show running-config
- Building configuration...
- Current configuration:
- More -
- Any lines that appear after the
word "End"
Add the no
shutdown command to the end of each interface section. Click File > Save to
save a clean version of the configuration.
The backup
configuration can be restored from a HyperTerminal session. Before the
configuration is restored any remaining configuration should be removed from
the router. To do this, enter the erase startup-config command at the
privileged EXEC prompt and then enter the reload command to restart the router.
HyperTerminal can
be used to restore a configuration. Use the following steps to copy a clean
backup of the configuration into a router:
- Enter router global
configuration mode.
- Click on Transfer > Send
Text File in HyperTerminal.
- Select the name of the file for
the saved backup configuration.
- Watch as the lines of the file
are entered into the router.
- Observe any errors.
- Press Ctrl-Z to exit global
configuration mode after the configuration is entered.
- Restore the startup
configuration with the copy running-config startup-config command.
The next page
will explain how TFTP can be used to mange IOS images.
16.2
Managing the Cisco File System
16.2.5
Managing IOS images using TFTP
The page will
show students how to store IOS images on a TFTP server.
The IOS may need
to be backed up, upgraded, or restored using the copy command. When a router
first arrives, the IOS should be backed up. The IOS backup can be initiated
from the privileged EXEC mode with the copy flash tftp command. This IOS image
can be stored in a central server with other IOS images. These images can be
used to restore or upgrade the IOS on the routers and switches in a network.
This server should have a TFTP service running. The router will prompt the user
to enter the IP address of the TFTP server and to specify a destination
filename.
To restore or
upgrade the IOS from the server use the copy tftp flash command as shown in
Figure . The router will prompt the user to enter the IP address of the TFTP
server. Next, the router will prompt the user for the filename of the IOS image
on the server. The router may then prompt the user to erase flash. This often
happens if there is not sufficient flash available for the new image. As the
image is erased from flash, a series of e’s will appear to show the erase
process.
As each datagram
of the IOS image file is downloaded, an exclamation mark (!) will be displayed.
This IOS image is several megabytes and may take a long time to download.
The new flash
image will be verified after it is downloaded. The router is now ready to be
reloaded to use the new IOS image.
The Lab Activity
will allow students to back up a copy of a router IOS onto a TFTP server.
The next page
will show students how ROMmon and Xmodem can be used to manage IOS images.
16.2
Managing the Cisco File System
16.2.6
Managing IOS images using Xmodem
This page will
explain how ROMmon and Xmodem can be used to restore IOS software images.
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 by the rommon 1> prompt.
This first step
in this process is to identify why the IOS image did not load from flash. This
could be due to a corrupt or missing image. The flash should be examined with
the dir flash: command.
If an image is
located that appears to be valid, the user should attempt to boot from that
image. This is done with the boot flash: command. For example if the image name
is c2600-is-mz.121-5, the command is as follows:
rommon 1>boot
flash:c2600-is-mz.121-5
If the router
boots properly, the user should check two items to determine why the router did
not use the IOS image from flash and booted to the ROMmon instead. First, use
the show version command to check the configuration register to ensure that it
is configured for the default boot sequence. If the configuration register
value is correct, use the show startup-config command to see if there is a boot
system command that instructs the router to use the IOS for ROMmon.
If the router
will not properly boot from the image or there is no IOS image, a new IOS will
need to be downloaded. To recover the IOS file, a user can use Xmodem to
restore the image through the console or use TFTP to download the image from
the ROMmon mode.
Download with
Xmodem from ROMmon
To restore the
IOS through the console, the local PC needs to have a copy of the IOS file to
restore and a terminal emulation program such as HyperTerminal. The IOS can be
restored with the default console speed of 9600 bps. The baud rate can be
changed to 115200 bps to speed up the download. Use the confreg command to
change the console speed from ROMmon mode. After the confreg command is entered,
the router will prompt for the parameters that can be changed.
When the “change
console baud rate? y/n [n]:” prompt appears, if the user selects y, the router
will prompt the user to select the new speed. After the console speed is
changed, restart the router into ROMmon mode. The terminal session at 9600 bps
is terminated and a new session is started at 115200 bps to match the console
speed.
The xmodem
command can be used from the ROMmon mode to restore an IOS software image from
the PC. The format of the command is xmodem -c image_file_name. For example, to
restore an IOS image file named c2600-is-mz.122-10a.bin, use the following
command:
xmodem -c
c2600-is-mz.122-10a.bin
The -c instructs
the Xmodem process to use cyclic redundancy check (CRC) for error checking
during the download.
The router will
prompt the user to not begin the transfer and present a warning message. The
warning message will inform the user that the bootflash will be erased and will
ask for confirmation to continue. When the process is continued, the router
will then prompt to start the transfer.
Now the Xmodem
transfer needs to be started from the terminal emulator. In HyperTerminal,
select Transfer > Send File. In the Send File popup specify the image name
and location, select Xmodem as the protocol, and start the transfer. The
Sending File popup will display the status of the transfer.
After the
transfer is complete, a message will indicate that flash is being erased. This
is followed by the “Download Complete!” message. Before the router is
restarted, set the console speed back to 9600 and the config register back to
0x2102. Enter the command config-register 0x2102 at the privileged EXEC prompt.
While the router
reboots, end the 115200 bps terminal session and begin a 9600 bps session.
The Lab
Activities will teach students how to gain access to a router to recover a
password and how to manage IOS images with ROMmon and Xmodem.
The next page
will introduce the ROMmon environment variables.
16.2
Managing the Cisco File System
16.2.7
Environment variables
This page will
explain what the ROMmon environment variables are and how they are used.
The IOS can also
be restored from a TFTP session. The fastest way to restore an IOS image to the
router is to use TFTP from ROMmon to download the image. To do this, set the
environmental variables and then use the tftpdnld command.
Since the ROMmon
has very limited functions, no configuration file is loaded during boot. As a
result, the router has no IP or interface configuration. The environmental
variables provide a minimal configuration to allow for the TFTP of the IOS. The
ROMmon TFTP transfer works only on the first LAN port so a simple set of IP
parameters are set for this interface. To set a ROMmon environment variable,
type the variable name, then the equal sign (=), and the value for the
variable. For example, to set the IP address to 10.0.0.1, type
IP_ADDRESS=10.0.0.1 at the ROMmon prompt.
NOTE:
All variable
names are case sensitive.
The minimum
variables required to use tftpdnld are as follows:
- IP_ADDRESS - The IP address on
the LAN interface
- IP_SUBNET_MASK - The subnet
mask for the LAN interface
- DEFAULT_GATEWAY - The default
gateway for the LAN interface
- TFTP_SERVER - The IP address of
the TFTP server
- TFTP_FILE - The IOS filename on
the server
Use the set
command to check the ROMmon environment variables.
Once the
variables are set for the IOS download, the tftpdnld command is entered with no
arguments. The ROMmon will echo the variables and then a confirmation prompt
will appear with a warning that this will erase the flash.
As each datagram
of the IOS file is received, an exclamation point (!) will be displayed. When
the complete IOS file has been received, the flash will be erased and the new IOS
image file written. Appropriate messages will be displayed as the process is
completed.
When the new
image is written into flash and the ROMmon prompt is displayed, the router can
be restarted by entering the reset command or typing i. The router should now
boot from the new IOS image in flash.
The next page
will describe some commands that can be used to verify a router file system.
16.2
Managing the Cisco File System
16.2.8
File system verification
This page will
review some commands that can be used to verify the router file system. One of
these is the show version command. The
show version command can be used to check the current image and the total
amount of flash. It also verifies two other items that relate to how the IOS is
loaded. It identifies the source of the IOS image that the router used to boot
and displays the configuration register. Check the boot field setting of the
configuration register to determine the location from which the router will
load the IOS. If these do not agree, there may be a corrupt or missing IOS
image in flash or there may be boot system commands in the startup
configuration.
The show flash
command can also be used to verify the file system. This command is used to identify IOS images
in flash and the amount of flash that is available. This command is often used
to confirm that there is ample space to store a new IOS image.
As previously
mentioned, the configuration file may contain boot system commands. These
commands can be used to identify the source of the desired IOS boot image.
Multiple boot system commands may be used to create a fallback sequence to
discover and load an IOS. These boot system commands will be processed in the
order of their appearance in the configuration file.
This page concludes
this lesson. The next page will summarize the main points from this module.
Summary
This page
summarizes the topics discussed in this module.
The default
configuration register setting can be changed with the global configuration
mode command config-register.
The boot sequence
for the Cisco IOS can specify the fallback sequence that is used to boot Cisco
IOS software. A common fallback sequence would be to load first from flash
memory, which is not vulnerable to network failures. The network server would
be used next if the flash memory were corrupt. Finally if the first two methods
failed the router would boot from ROM. However, the system image in ROM will
likely be a subset of the full Cisco IOS image.
The command copy
running-config startup-config saves the configuration commands in NVRAM. The
router will execute the boot system commands as needed in the order in which
they were originally entered in the configuration mode. If a configuration
register setting is incorrect, the Cisco IOS will not load from flash.
To troubleshoot
the boot sequence, use the show running-config command and look for a boot
system statement near the top of the configuration. If the boot system
statement points to an incorrect IOS image, use the no form of the command to
delete the statement.
The two types of
software required to operate a router and a switch are the operating systems
and the configuration. The Cisco IOS allows the hardware to function. The
configuration file or config is the software that contains the instructions
that define how the device is to route or switch the packets that enter the
device.
The naming
convention for Cisco IOS files includes four parts. The first part of the Cisco
IOS file name identifies the hardware platform for which this image is
designed. The second part of the Cisco IOS file name identifies the various
features that this file contains. The third part of the file name indicates the
file format. It specifies if the Cisco IOS is stored in flash in a compressed
format and whether it is relocatable. The fourth part of the file name
identifies the release of the Cisco IOS. As newer versions of the Cisco IOS are
developed, the numerical version number increases.
The active
configuration for a Cisco router is maintained in RAM and the default location
for the startup configuration is NVRAM. The copy running-config tftp command
can be used to back up copies of the configuration to a TFTP server.
Another way to
create a backup copy of the configuration is to capture the output of the show
running-config command. To do this from the terminal session, copy the output,
paste it to a text file, and then save the text file. After the capture is
complete, the configuration file needs to be edited to remove extra text. To
add a comment, begin a line with an exclamation mark (!).
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