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Appendix A      Cisco IOS Basic Skills
Using Commands
Using Commands
This section provides some tips about entering Cisco IOS commands at the 
command-line interface (CLI).
Abbreviating Commands
You only have to enter enough characters for the router to recognize the command 
as unique. This example shows how to enter the show version command:
router # sh v
Undoing Commands
If you want to disable a feature or undo a command you entered, you can enter the 
keyword no before most commands; for example, no ip routing. 
Command-Line Error Messages
Ta b l e A - 2 lists some error messages that you might encounter while using the CLI 
to configure your router. 
						

							 
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Saving Configuration Changes
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Saving Configuration Changes
You need to enter the copy running-config startup-config command to save 
your configuration changes to nonvolatile RAM (NVRAM) so that they are not 
lost if there is a system reload or power outage. This example shows how to use 
this command to save your changes:
router # copy running-config startup-config
Destination filename [startup-config]?
Press Return to accept the default destination filename startup-config, or enter 
your desired destination filename and press Return.
Table A-3 Common CLI Error Messages
Error Message  Meaning How to Get Help
% Ambiguous command: 
show conYou did not enter enough 
characters for your router to 
recognize the command.Reenter the command followed 
by a question mark (?) with no 
space between the command and 
the question mark.
The possible keywords that you 
can enter with the command are 
displayed.
% Incomplete command.You did not enter all of the 
keywords or values required by 
this command.Reenter the command followed 
by a question mark (?) with no 
space between the command and 
the question mark.
The possible keywords that you 
can enter with the command are 
displayed.
% Invalid input detected at 
‘^’ marker.You entered the command 
incorrectly. The error occurred 
where the caret mark (^) appears.Enter a question mark (?) to 
display all of the commands that 
are available in this command 
mode. 
						

							 
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Appendix A      Cisco IOS Basic Skills
Partition and Squeeze
It might take a minute or two to save the configuration to NVRAM. After the 
configuration has been saved, the following message appears:
Building configuration...
router #
Partition and Squeeze 
Partition and squeeze are supported on Cisco 831, Cisco 837, SOHO 91, and 
SOHO 97 routers. When a Flash memory device is full, you may want to rearrange 
the files so that the space used by the deleted files can be reclaimed. If you wish 
to permanently delete files on a Flash memory device, you may use the squeeze 
operation to remove all the deleted files from the Flash file systems and recover 
the space that the files occupied. The squeeze operation can take as long as several 
minutes because it involves erasing and rewriting almost an entire Flash memory 
space. To enable the squeeze operation, all of the Flash device file systems, 
including the partitions if any, must be erased before the squeeze command can 
be used. There are provisions in the erase command to disable this squeeze utility. 
The partition feature requires at least two banks of Flash memory. The 
partitioning does not cause an existing file in Flash memory to be split across the 
partitions. The number of partitions that you can create in a Flash memory device 
is equal to the number of banks in the device, but the maximum number of 
partitions is 8. 
Enter the router(config)#partition flash-filesystem command to create the 
partition. The command separates Flash memory into up to 8 partition. The 
squeeze command will not delete files saved in partition that is not marked as 
“deleted.” 
Enter the #squeeze flash command to permanently delete all files marked “delete” 
on a Flash memory device.
Use the following steps to erase an entire Flash memory system, beginning in 
global configuration mode. 
						

							 
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Summary
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NoteThe squeeze function is applicable only to the Cisco 831, Cisco 837, 
Cisco SOHO 91, and Cisco SOHO 97 routers. 
Summary
Now that you have reviewed some Cisco IOS software basics, you can begin to 
configure your router. Remember the following:
You can use the question mark (?) and arrow keys to help you enter 
commands.
Each command mode restricts you to a set of commands. If you are having 
difficulty entering a command, check the prompt, and then enter the question 
mark (?) for a list of available commands. You might be in the wrong 
command mode or using the wrong syntax. 
If you want to disable a feature, enter the keyword no before the command; 
for example, no ip routing.
Save your configuration changes to NVRAM so that they are not lost if there 
is a system reload or power outage. Command Task
Step 1router(config)# no partition flash-filesystemRemove all partitions on the specific Flash 
file system. The reason for removing 
partitions is to ensure that the entire Flash file 
system is erased. The squeeze command can 
be used in a Flash file memory with partitions 
after the Flash file memory has been erased.
Step 2router# erase filesystemErase all of the files on the specified Flash 
system. 
						

							 
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Appendix A      Cisco IOS Basic Skills
Where to Go Next
Where to Go Next
To configure your router, see Chapter 7, “Router Feature Configuration,” and 
Chapter 8, “Advanced Router Configuration.” 
						

							 
Appendix A      Cisco IOS Basic Skills
Where to Go Next
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APPENDIXB
ROM Monitor
This appendix describes the Cisco 820 series routers ROM monitor (also called 
the bootstrap program). The ROM monitor firmware runs when the router is 
powered up or reset. The firmware helps to initialize the processor hardware and 
boot the operating system software. You can use the ROM monitor to perform 
certain configuration tasks, such as recovering a lost password or downloading 
software over the console port. If there is no Cisco IOS software image loaded on 
the router, the ROM monitor runs the router.
This appendix contains the following sections:
Entering the ROM Monitor, page B-2
ROM Monitor Commands, page B-5
Command Descriptions, page B-6
Disaster Recovery with TFTP Download, page B-7
Using the TFTP Download Command Without Writing the Image to Flash 
Memory, page B-10
Configuration Register, page B-11
Console Download, page B-12
Debug Commands, page B-14
Disaster Recovery with Console Download of Cisco IOS Software, 
page B-16 
						

							 
Appendix B      ROM Monitor
Entering the ROM Monitor
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Entering the ROM Monitor
To use the ROM monitor, you must be using a terminal or PC that is connected to 
the router over the console port. Refer to the installation chapter in the Cisco 827 
Routers Hardware Installation Guide that came with the router to connect the 
router to a PC or terminal.
Perform these steps to configure the router to boot up in ROM monitor mode the 
next time it is rebooted.
TimesaverBreak (system interrupt) is always enabled for 60 seconds after the router reboots, 
regardless of whether it is set to on or off in the configuration register. During this 
60-second window, you can break to the ROM monitor prompt by pressing the 
Break key.  Command Task
Step 1enableIf an enable password is configured, enter the 
enable command and the enable password to 
enter privileged EXEC mode.
Step 2configure terminalEnter global configuration mode.
Step 3config-reg 0x0Reset the configuration register.
Step 4exitExit global configuration mode.
Step 5reloadReboot the router with the new configuration 
register value. The router remains in ROM 
monitor and does not boot the Cisco IOS 
software.
As long as the configuration value is 0x0, you 
must manually boot the operating system 
from the console. See the boot command in 
the “Command Descriptions” section on 
page B-6. 
After the router reboots, it is in ROM monitor 
mode. The number in the prompt increments 
with each new line. 
						

							 
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Appendix B      ROM Monitor
Entering the ROM Monitor
Who Should Upgrade ROMMON and Why
To ensure proper functionality and prevent router inoperability, upgrade the ROM 
monitor (ROMMON) image to the latest version before downloading the 
Cisco IOS image. The ROMMON images are backward compatible with all 
previously released Cisco IOS software images.
Where to Find New Versions of ROMMON
Go to the following website for a new versions of ROMMON. You will need to 
enter your Cisco login account to access the website. 
http://www.cisco.com/kobayashi/sw-center/sw-ios.shtml
Performing the Upgrade
Follow the steps below to upgrade the ROMMON image, beginning in ROMMON 
mode.
Step 1Download the ROMMON image from CCO, and place it on your TFTP server.
Step 2Connect the Ethernet cable to the same hub that the TFTP server is attached to.
Step 3Place your Cisco router in ROMMON mode by sending the Telnet command 
break during a router reboot sequence. Make sure that all the parameters are exact 
and are in capital letters. The following prompt is displayed when the router is in 
ROMMON mode:
rommon 1 >
Step 4Set the following parameters.
rommon 1 > IP_ADDRESS=ip_address
rommon 1 > IP_SUBNET_MASK=ip_subnet_mask
rommon 1 > DEFAULT_GATEWAY=default_gateway
rommon 1 > TFTP_SERVER=TFTP_server
rommon 1 > TFTP_FILE=TFTP_file
rommon 1 > 
						

							 
Appendix B      ROM Monitor
Entering the ROM Monitor
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The parameters have the following meanings.
Step 5Verify parameter settings, using the set command. Correct any errors by 
reentering the parameters and their values. For example:
rommon > set
TFTP_CHECKSUM=0
IP_SUBNET_MASK=255.255.255.0
DEFAULT_GATEWAY=1.6.0.1
TFTP_SERVER=223.255.254.254
IP_ADDRESS=1.6.97.20
TFTP_FILE=/auto/tftpload/ROMMON/C820_RM_ALT.srec.122-1r.XE2
Step 6Upgrade the ROMMON image, using the tftpdnld -u command.
NoteYou might be prompted to reset the router in ROMMON mode by 
entering the reset command. If you receive this prompt, reset the router 
before you perform Step 1 througth Step 5 again.
rommon >tftpdnld -u
IP_ADDRESS:1.6.97.20
IP_SUBNET_MASK:255.255.255.0
DEFAULT_GATEWAY:1.6.0.1
TFTP_SERVER:223.255.254.254
TFTP_FILE:/auto/tftpload/ROMMON/C820_RM_ALT.srec.122-1r.XE2
WARNING: alternate copy of rommon exists, filename:C820_RM_ALT.srec 
all existing data in the alternate copy of rommon will be lost.
Do you wish to continue? y/n: [n]:
Parameter Value
IP_ADDRESS= IP address of the router
IP_SUBNET_MASK= Router subnet mask
DEFAULT_GATEWAY= IP address of the router default 
gateway
TFTP_SERVER= IP address of the TFTP server on which 
the ROMMON image is located
TFTP_FILE= The path and file name of the 
ROMMON image