To define the character you ent er at a vacant terminal to begin a terminal session, use the activation-character command in line configuration mode. To make any character activate a terminal, use the no form of this command.

Syntax Description

Command Default

Return (decimal 13)

Command Modes

Line configuration (config-line)

Command History

Usage Guidelines

See the "ASCII Character Set and Hexadecimal Values" document for a list of ASCII characters.

Note	If you are using the autoselect function, set the activation character to the default, Return, and exec-character-bits to 7. If you change these defaults, the application will not recognize the activation request.

To create a command alias, use the alias command in global configuration mode. To delete all aliases in a command mode or to delete a specific alias, and to revert to the original command syntax, use the no form of this command.

Syntax Description

Command Default

A set of six basic EXEC mode aliases are enabled by default. See the "Usage Guidelines" section of this command for a list of default aliases.

Command Modes

Global configuration

Command History

Usage Guidelines

You can use simple words or abbreviations as command aliases.

The table below lists the basic EXEC mode aliases that are enabled by default.

The default aliases in the table above are predefined. These default aliases can be disabled with the no alias exec command.

Common keyword aliases (which cannot be disabled) include running-config (keyword alias for system:running-config) and startup-config (keyword alias for nvram:startup-config). See the description of the copy command for more information about these keyword aliases.

Note that aliases can be configured for keywords instead of entire commands. You can create, for example, an alias for the first part of any command and still enter the additional keywords and arguments as normal.

To determine the value for the mode argument, enter the command mode in which you would issue the original command (and in which you will issue the alias) and enter the ? command. The name of the command mode should appear at the top of the list of commands. For example, the second line in the following sample output shows the name of the command mode as "Interface configuration":

Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface e0
Router(config-if)# ?
Interface configuration commands:
  access-expression       Build a bridge boolean access expression
 .
 .
 .

To match the name of the command mode to the acceptable mode keyword for the alias command, issue the alias ? command. As shown in the following sample output, the keyword needed to create a command alias for the access-expression command is interface:

Router(config)# alias ?
  accept-dialin          VPDN group accept dialin configuration mode
  accept-dialout         VPDN group accept dialout configuration mode
  address-family         Address Family configuration mode
  call-discriminator     Call Discriminator Configuration
  cascustom              Cas custom configuration mode
  clid-group             CLID group configuration mode
  configure              Global configuration mode
  congestion             Frame Relay congestion configuration mode
  controller             Controller configuration mode
  cptone-set             custom call progress tone configuration mode
  customer-profile       customer profile configuration mode
  dhcp                   DHCP pool configuration mode
  dnis-group             DNIS group configuration mode
  exec                   Exec mode
  flow-cache             Flow aggregation cache config mode
  fr-fr                  FR/FR connection configuration mode
  interface              Interface configuration mode
 .
 .
 .
Router(config)# alias interface express access-expression

When you use online help, command aliases are indicated by an asterisk (*), and displayed in the following format:

*command-alias =original-command

For example, the lo command alias is shown here along with other EXEC mode commands that start with "lo":

Router# lo?
*lo=logout  lock  login  logout 

When you use online help, aliases that contain multiple keyword elements separated by spaces are displayed in quotes, as shown here:

Router(config)#alias exec device-mail telnet device.cisco.com 25
Router(config)#end
Router#device-mail?
*device-mail="telnet device.cisco.com 25" 

To list only commands and omit aliases, begin your input line with a space. In the following example, the alias td is not shown, because there is a space before the t?command line.

Router(config)#alias exec td telnet device
Router(config)#end
Router# t?
telnet terminal test tn3270 trace

To circumvent command aliases, use a space before entering the command. In the following example, the command alias express is not recognized because a space is used before the command.

Router(config-if)#exp?
*express=access-expression 
Router(config-if)# express ?
 
% Unrecognized command 

As with commands, you can use online help to display the arguments and keywords that can follow a command alias. In the following example,the alias td is created to represent the command telnet device. The /debugand /lineswitchescan be added to telnet device to modify the command:

Router(config)#alias exec td telnet device
Router(config)#end
Router#td ?
      /debug     Enable telnet debugging mode
      /line      Enable telnet line mode
      ...
      whois      Whois port
      <cr>
Router# telnet device 

You must enter the complete syntax for the command alias. Partial syntax for aliases is not accepted. In the following example, the parser does not recognize the command t as indicating the alias td:

Router# t
 
% Ambiguous command: "t"

Related Commands

To enter archive configuration mode, use the archive command in global configuration mode.

Syntax Description

This command has no arguments or keywords.

Command Default

None

Command Modes

Global configuration

Command History

Related Commands

To save a copy of the current running configuration to the Cisco IOS configuration archive, use the archive config command in privileged EXEC mode.

Syntax Description

This command has no arguments or keywords.

Command Modes

Privileged EXEC (#)

Command History

Usage Guidelines

Note	Before using this command, you must configure the path command in order to specify the location and filename prefix for the files in the Cisco IOS configuration archive.

The Cisco IOS configuration archive is intended to provide a mechanism to store, organize, and manage an archive of Cisco IOS configuration files to enhance the configuration rollback capability provided by the configure replace command. Before this feature was introduced, you could save copies of the running configuration using the copy running-config destination-url command, storing the target file either locally or remotely. However, this method lacked any automated file management. On the other hand, the Configuration Replace and Configuration Rollback feature provides the capability to automatically save copies of the running configuration to the Cisco IOS configuration archive. These archived files serve as checkpoint configuration references and can be used by the configure replace command to revert to previous configuration states.

The archive config command allows you to save Cisco IOS configurations in the configuration archive using a standard location and filename prefix that is automatically appended with an incremental version number (and optional time stamp) as each consecutive file is saved. This functionality provides a means for consistent identification of saved Cisco IOS configuration files. You can specify how many versions of the running configuration are kept in the archive. After the maximum number of files has been saved in the archive, the oldest file is automatically deleted when the next, most recent file is saved. The show archive command displays information for all configuration files saved in the Cisco IOS configuration archive.

Related Commands

To save the persisted commands in the configuration log to the Cisco IOS secure file system, use the archive log config persistent save command in privileged EXEC mode.

Syntax Description

This command has no arguments or keywords.

Command Default

If this command is not entered, the persisted configuration commands in the archive log are not saved to the Cisco IOS secure file system.

Command Modes

Privileged EXEC (#).

Command History

Usage Guidelines

If the router is in the persistent periodic mode, the persistent timer is restarted.

Related Commands

To create a TAR file, to list files in a TAR file, or to extract the files from a TAR file, use the archive tar command in privileged EXEC mode.

Syntax Description

Command Default

The TAR archive file is not created.

Command Modes

Privileged EXEC (#)

Command History

Usage Guidelines

Filenames, directory names, and image names are case sensitive.

The TAR file is an archive file from which you can extract files by using the archive tarcommand.

To configure extended BOOTP requests for asynchronous interfaces as defined in RFC 1084, use the async-bootp command in global configuration mode. To restore the default, use the noform of this command.

Syntax Description

Command Default

If no extended BOOTP commands are entered, the Cisco IOS software generates a gateway and subnet mask appropriate for the local network.

Command Modes

Global configuration

Command History

Usage Guidelines

Use the show async-bootp EXEC command to list the configured parameters. Use the no async-bootp command to clear the list.

Related Commands

To connect to a specific line card or module from a remote location for the purpose of executing monitoring and maintenance commands on that line card or module, use the attach command in privileged EXEC mode. To exit from the Cisco IOS software image on the line card and return to the Cisco IOS image on the main (Supervisor) module, use the exit command.

Syntax Description

Command Default

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Usage Guidelines

Cisco 12000 Series

You must first use the attach privileged EXEC command to access the Cisco IOS software image on a line card before using line card-specific show EXEC commands. Alternatively, you can use the execute-on privileged EXEC command to execute a show command on a specific line card.

After you connect to the Cisco IOS image on the line card using the attach command, the prompt changes to LC-Slotx# , where x is the slot number of the line card.

The commands executed on the line card use the Cisco IOS image on that line card.

You can also use the execute-on slot privileged EXEC command to execute commands on one or all line cards.

Note	Do not execute the configEXEC command from the Cisco IOS software image on the line card.

Cisco 7600 Series and Catalyst 6500 Series

Caution

After you enter the attach or remote login command to access another console from your switch, if you enter global or interface configuration mode commands, the switch might reset.

Th e v alid values for the module-number argument depend on the chassis that is used. For example, if you have a 13-slot chassis, valid values for the module number are from 1 to 13.

This command is supported on Distributed Forwarding Card (DFC)-equipped modules, FlexWan modules, and the supervisor engine only.

When you execute the attach module-number command, the prompt changes to Router-dfcx# or Switch-sp#, depending on the type of module to which you are connecting.

The behavior of the attach command is identical to that of the remote login module numcommand.

There are two ways to end this session:

• You can enter the exit command as follows:

Router-dfc3# exit
[Connection to Switch closed by foreign host]
Router#

• You can press Ctrl-C three times as follows:

Router-dfc3# ^C
Router-dfc3# ^C
Router-dfc3# ^C
Terminate remote login session? [confirm] y
[Connection to Switch closed by local host]
Router#

Related Commands

To set the line for automatic baud rate detection (autobaud), use the autobaudcommand in line configuration mode. To disable automatic baud detection, use the noform of this command.

Syntax Description

This command has no arguments or keywords.

Command Default

Autobaud detection is disabled. Fixed speed of 9600 bps.

Command Modes

Line configuration

Command History

Usage Guidelines

The autobaud detection supports a range from 300 to 19200 baud. A line set for autobaud cannot be used for outgoing connections, nor can you set autobaud capability on a line using 19200 baud when the parity bit is set (because of hardware limitations).

Note	Automatic baud detection must be disabled by using the no autobaud command prior to setting the txspeed, rxspeed, or speed commands.

To enable automatic synchronization of the configuration files in NVRAM, use the auto-sync command in main-cpu redundancy configuration mode. To disable automatic synchronization, use the no form of this command.

Syntax Description

Command Default

For the Performance Routing Engines (PREs) on the Cisco uBR10012 universal broadband router, the system defaults to synchronizing all system files on the (auto-sync standard).

For the Supervisor Engines on the Cisco 7600 series routers, the system defaults to synchronizing the running configuration. (running-config).

At the Cisco RF Gateway 10 chassis level, all the system files are synchronized by default.

Cisco RF Gateway 10

Redundancy configuration (config-r)

Main CPU redundancy configuration (config-r-mc)

Command History

Usage Guidelines

Cisco 7600 Series Routers

If you enter the no auto-sync standard command, no automatic synchronizations occur. If you want to enable any of the keywords, you have to enter the appropriate command for each keyword.

The auto-synccommand is not supported in RPR+ mode.

Cisco uBR10012 Universal Broadband Router

By default, the system synchronizes all system files, which is the typical setting for most applications. However, you might want exclude certain files from synchronization for specialized applications.

For example, if you have configured the active and standby PRE1 (or PRE2) modules to run different versions of Cisco IOS software, you might want to use different configuration files as well. In this case, you would not synchronize the startup configuration file.

Cisco RF Gateway 10

We recommend that you use the auto-sync standard command to ensure that all system files are synchronized between the two Supervisor modules. The no auto-sync command is not used in production plants.

Related Commands

To configure the Cisco IOS Auto-Upgrade Manager disk cleanup utility, use the autoupgrade disk-cleanup command in global configuration mode. To disable this configuration, use the no form of this command.

Syntax Description

Command Default

By default, the crashinfo files, the core files, and the Cisco IOS software images are deleted by the Cisco IOS Auto-Upgrade Manager disk cleanup utility, and the filesystems that support the undelete operation are not cleaned up.

Command Modes

Global configuration (config)

Command History

Related Commands

To configure the URL of the Intelligent Download Application (IDA) running on www.cisco.com, use the autoupgrade ida url command in global configuration mode. The router will send the image download requests to the configured URL. To disable this URL, use the no form of this command.

Syntax Description

Command Default

Default URL: https://www.cisco.com/cgi-bin/ida/locator/locator.pl

Command Modes

Global configuration (config)

Command History

Usage Guidelines

Use the autoupgrade ida url command to configure a new URL for the IDA server, if it is not present in the default location.

Related Commands

To configure the address to which status email is to be sent and the outgoing email server, use the autoupgrade status email command in global configuration mode. To disable status email, use the no form of this command.

Syntax Description

Command Default

Status email is not sent unless the address is configured. The recipient email address and SMTP server have to be configured in order to receive AUM status email.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

Use this command to configure the email-address where AUM status email can be sent.

Related Commands

To specify and enable a message to be displayed when an EXEC process is created (an EXEC banner), use the banner exec command in global configuration mode. To delete the existing EXEC banner, use the no form of this command.

Syntax Description

Command Default

Disabled (no EXEC banner is displayed).

Command Modes

Global configuration

Command History

Usage Guidelines

This command specifies a message to be displayed when an EXEC process is created (a line is activated, or an incoming connection is made to a vty). Follow this command with one or more blank spaces and a delimiting character of your choice. Then enter one or more lines of text, terminating the message with the second occurrence of the delimiting character.

When a user connects to a router, the message-of-the-day (MOTD) banner appears first, followed by the login banner and prompts. After the user logs in to the router, the EXEC banner or incoming banner will be displayed, depending on the type of connection. For a reverse Telnet login, the incoming banner will be displayed. For all other connections, the router will display the EXEC banner.

To disable the EXEC banner on a particular line or lines, use the no exec-banner line configuration command.

To customize the banner, use tokens in the form $(token ) in the message text. Tokens will display current Cisco IOS configuration variables, such as the router's host name and IP address. The tokens are described in the table below.

Related Commands

To define and enable a banner to be displayed when there is an incoming connection to a terminal line from a host on the network, use the banner incoming command in global configuration mode. To delete the incoming connection banner, use the no form of this command.

Syntax Description

Command Default

Disabled (no incoming banner is displayed).

Command Modes

Global configuration

Command History

Usage Guidelines

Follow the banner incomingcommand with one or more blank spaces and a delimiting character of your choice. Then enter one or more lines of text, terminating the message with the second occurrence of the delimiting character.

An incoming connection is one initiated from the network side of the router. Incoming connections are also called reverse Telnet sessions. These sessions can display MOTD banners and incoming banners, but they do not display EXEC banners. Use the no motd-banner line configuration command to disable the MOTD banner for reverse Telnet sessions on asynchronous lines.

When a user connects to the router, the message-of-the-day (MOTD) banner (if configured) appears first, before the login prompt. After the user successfully logs in to the router, the EXEC banner or incoming banner will be displayed, depending on the type of connection. For a reverse Telnet login, the incoming banner will be displayed. For all other connections, the router will display the EXEC banner.

Incoming banners cannot be suppressed. If you do not want the incoming banner to appear, you must delete it with the no banner incoming command.

To customize the banner, use tokens in the form $(token ) in the message text. Tokens will display current Cisco IOS configuration variables, such as the router's host name and IP address. The tokens are described in the table below.

Related Commands

To define and enable a customized banner to be displayed before the username and password login prompts, use the banner login command in global configuration mode. To disable the login banner, use no form of this command.

Syntax Description

Command Default

Disabled (no login banner is displayed).

Command Modes

Global configuration

Command History

Usage Guidelines

Follow the banner login command with one or more blank spaces and a delimiting character of your choice. Then enter one or more lines of text, terminating the message with the second occurrence of the delimiting character.

When a user connects to the router, the message-of-the-day (MOTD) banner (if configured) appears first, followed by the login banner and prompts. After the user successfully logs in to the router, the EXEC banner or incoming banner will be displayed, depending on the type of connection. For a reverse Telnet login, the incoming banner will be displayed. For all other connections, the router will display the EXEC banner.

To customize the banner, use tokens in the form $(token ) in the message text. Tokens will display current Cisco IOS configuration variables, such as the router's host name and IP address. The tokens are described in the table below.

Related Commands

To define and enable a message-of-the-day (MOTD) banner, use the banner motd command in global configuration mode. To delete the MOTD banner, use the no form of this command.

Syntax Description

Command Default

Disabled (no MOTD banner is displayed).

Command Modes

Global configuration

Command History

Usage Guidelines

Follow this command with one or more blank spaces and a delimiting character of your choice. Then enter one or more lines of text, terminating the message with the second occurrence of the delimiting character.

This MOTD banner is displayed to all terminals connected and is useful for sending messages that affect all users (such as impending system shutdowns). Use the no exec-banner or no motd-banner command to disable the MOTD banner on a line. The no exec-banner command also disables the EXEC banner on the line.

When a user connects to the router, the MOTD banner appears before the login prompt. After the user logs in to the router, the EXEC banner or incoming banner will be displayed, depending on the type of connection. For a reverse Telnet login, the incoming banner will be displayed. For all other connections, the router will display the EXEC banner.

To customize the banner, use tokens in the form $(token ) in the message text. Tokens will display current Cisco IOS configuration variables, such as the router's host name and IP address. The tokens are described in the table below.

Related Commands

To customize the banner that is displayed when a Serial Line Internet Protocol (SLIP) or PPP connection is made, use the banner slip-ppp command in global configuration mode. To restore the default SLIP or PPP banner, use the no form of this command.

Syntax Description

Command Default

The default SLIP or PPP banner message is:

Entering encapsulation mode.
Async interface address is unnumbered (Ethernet0)
Your IP address is 10.000.0.0 MTU is 1500 bytes

The banner message when using the service old-slip-prompt command is:

Entering encapsulation mode.
Your IP address is 10.100.0.0 MTU is 1500 bytes

where encapsulation is SLIP or PPP.

Command Modes

Global configuration

Command History

Usage Guidelines

Follow this command with one or more blank spaces and a delimiting character of your choice. Then enter one or more lines of text, terminating the message with the second occurrence of the delimiting character.

Use this command to define a custom SLIP or PPP connection message. This is useful when legacy client applications require a specialized connection string. To customize the banner, use tokens in the form $(token ) in the message text. Tokens will display current Cisco IOS configuration variables, such as the routers host name, IP address, encapsulation type, and Maximum Transfer Unit (MTU) size. The banner tokens are described in the table below.

Related Commands

To boot the router manually, use the bootcommand in ROM monitor mode. The syntax of this command varies according to the platform and ROM monitor version.

Syntax Description

Command Default

For most platforms, if you enter the boot command and press Enter, the router boots from ROM by default. However, for some platforms, such as the Cisco 3600 series routers, if you enter the boot command and press Enter, the router boots the first image in Flash memory. Refer to the documentation for your platform for information about the default image.

Command Modes

ROM monitor

Command History

Usage Guidelines

To determine which form of this command to use, refer to the documentation for your platform or use the CLI help (?) feature.

Use this command only when your router cannot find the boot configuration information needed in NVRAM. To enter ROM monitor mode, use one of the following methods:

• Enter the reload EXEC command, then press the Break key during the first 60 seconds of startup.
• Set the configuration register bits 0 to 3 to zero (for example, set the configuration register to 0x0) and enter the reload command.

The ROM Monitor prompt is either ">" or, for newer platforms, "rommon x >". Enter only lowercase commands.

These commands work only if there is a valid image to boot. Also, from the ROM monitor prompt, issuing a prior reset command is necessary for the boot to be consistently successful.

In Cisco IOS Release 12.3(4)T, MONLIB was modified to search in media for a valid Cisco IOS image. This change prevents boot failures that result when the first file read in disk or flash is not a valid Cisco IOS image.

Refer to your hardware documentation for information on correct jumper settings for your platform.

Note	For some platforms the flash keyword is now required. If your attempts to use the boot command are failing using the older boot flash:x:[filename ] syntax, try using the boot flash flash:x:[filename ] syntax.

Related Commands

To specify the location of the boot image that ROM uses for booting, use the boot bootldr command in global configuration mode. To remove this boot image specification, use the no form of this command.

Syntax Description

Command Default

Refer to your platform documentation for the location of the default boot image.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

The boot bootldr command sets the BOOTLDR variable in the current running configuration. You must specify both the Flash file system and the filename.

Note

When you use this global configuration command, you affect only the running configuration. You must save the variable setting to your startup configuration to place the information under ROM monitor control and to have the variable function as expected. Use the copy system:running-config nvram:startup-config command to save the variable from your running configuration to your startup configuration.

Note	The default length of the bootstring filename is 64 characters. Depending on the platform a longer bootstring filename can be used and supported.

The no form of the command sets the BOOTLDR variable to a null string. On the Cisco 7000 family routers , a null string causes the first image file in boot Flash memory to be used as the boot image that ROM uses for booting.

Use the show boot command to display the current value for the BOOTLDR variable.

Related Commands

To configure the filename that is used to boot a secondary bootstrap image, use the boot bootstrap command in global configuration mode. To disable booting from a secondary bootstrap image, use the no form of this command.

Syntax Description

Command Default

No secondary bootstrap is configured.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

The boot bootstrap command causes the router to load a secondary bootstrap image from the specied URL, such as from a remote server. After the bootstrap image is loaded, the bootstrap image loads the specified system image file. See the appropriate hardware installation guide for details on setting the configuration register and secondary bootstrap filename.

Use this command when you have attempted to load a system image but have run out of memory even after compressing the system image. Secondary bootstrap images allows you to load a larger system image through a smaller secondary image.

Related Commands

To s pecify the device and filename of the configuration file from which the system configures itself during initialization (startup), use the boot config command in global configuration mode. To return to the default location for the configuration file, use the no form of this command.

Syntax Description

Command Default

The default location for the configuration file is NVRAM (nvram:).

Command Modes

Global configuration (config)

Supported Platforms Other than Cisco 7600 Series Router

Command History

This command is available only on Class A and Class B file system platforms.

You set the CONFIG_FILE environment variable in the current running memory when you use the boot config command. This variable specifies the configuration file used for initialization (startup). The configuration file must be an ASCII file located in either NVRAM or flash memory.

The valid values for the device :argument and colonare as follows:

• For systems that are configured with a Supervisor Engine 2, the valid values are bootflash:, const_nvram:, flash:, nvram:, slot0:, sup-slot0:, and sup-bootflash:
• For systems that are configured with a Supervisor Engine 720, the valid values are disk0: and disk1:

The configuration file must be an ASCII file that is located in the specified file system.

The disk0: and disk1: keywords are for Class C file systems.

The bootflash:, slot0:, and sup-bootflash: keywords are for Class A file systems.

For Class A flash file systems, the CONFIG_FILE environment variable specifies the file system and filename of the configuration file to use for initialization (startup). You set the CONFIG_FILE environment variable in the current running memory when you use the boot config command. This variable specifies the configuration file used for initialization (startup).

When you use the boot config command, you affect only the running configuration. You must save the environment variable setting to your startup configuration to place the information under ROM monitor control and to have the environment variable function as expected. Use the copy system:running-config nvram:startup-config command to save the environment variable from your running configuration to your startup configuration.

The software displays an error message and does not update the CONFIG_FILE environment variable in the following situations:

• You specify nvram: as the file system, and it contains only a distilled version of the configuration. (A distilled configuration is one that does not contain access lists.)
• You specify a configuration file in the filename argument that does not exist or is not valid.

The router uses the NVRAM configuration during initialization when the CONFIG_FILE environment variable does not exist or when it is null (such as at first-time startup). If the software detects a problem with NVRAM or the configuration it contains, the device enters setup mode.

When you use the no form of this command, the router returns to using the default NVRAM configuration file as the startup configuration.

You can display the contents of the BOOT, BOOTLDR, and the CONFIG_FILE environment variables using the show bootvar command. This command displays the settings for these variables as they exist in the startup configuration and in the running configuration if a running configuration setting differs from a startup configuration setting.

When the boot config command is used, the distilled configuration is written into NVRAM and the system configuration is written into the file specified by the boot config command. If the distilled configuration exceeds the size of NVRAM, the system configuration gets truncated. Use the nvbypass keyword to prevent the system configuration from being truncated when the distilled configuration is larger than the size of NVRAM.

Related Commands

To specify the host-specific configuration file to be used at the next system startup, use the boot host command in global configuration mode. To restore the host configuration filename to the default, use the no form of this command.

Syntax Description

Command Default

If you do not specify a filename using this command, the router uses its configured host name to request a configuration file from a remote server. To form the configuration filename, the router converts its name to all lowercase letters, removes all domain information, and appends -confg or -config.

Command Modes

Global configuration

Command History

Usage Guidelines

This command instructs the system to "Boot using host-specific configuration file x ," where x is the filename specified in the remote-url argument. In other words, this command specifies the remote location and filename of the host-specific configuration file to be used at the next system startup, as well as the protocol to be used to obtain the file.

Before using the boot host command, use the service config global configuration command to enable the loading of the specified configuration file at reboot time. Without this command, the router ignores the boot host command and uses the configuration information in NVRAM. If the configuration information in NVRAM is invalid or missing, the service config command is enabled automatically.

The network server will attempt to load two configuration files from remote hosts. The first is the network configuration file containing commands that apply to all network servers on a network. Use the boot network command to identify the network configuration file. The second is the host configuration file containing commands that apply to one network server in particular. Use the boot host command to identify the host configuration file.

Note

Usually, the service config command is used in conjunction with the boot host or boot network command. You must enter the service config command to enable the router to automatically configure the system from the file specified by the boot host or boot network command. With IOS software versions 12.3(2)T , 12.3(1)B, and later, you no longer have to specify the service config command for the boot host or boot network command to be active. If you specify both the no service config command and the boot host command, the router attempts to find the specified host configuration file. The service config command can also be used without the boot host or boot network command. If you do not specify host or network configuration filenames, the router uses the default configuration files. The default network configuration file is network-confg. The default host configuration file is host-confg, where host is the hostname of the router. If the Cisco IOS software cannot resolve its hostname, the default host configuration file is router-confg.

Loading a Configuration File Using rcp

The rcp software requires that a client send the remote username on each rcp request to the network server. If the server has a directory structure (such as UNIX systems), the rcp implementation searches for the configuration files starting in the directory associated with the remote username.

When you load a configuration file from a server using rcp, the Cisco IOS software sends the first valid username in the following list:

1. The username specified in the file-URL, if a username is specified.
2. The username set by the ip rcmd remote-username command, if the command is configured.
3. The router host name.

Note	An account for the username must be defined on the destination server. If the network administrator of the destination server did not establish an account for the username, this command will not execute successfully.

Loading a Configuration File Using FTP

The FTP protocol requires a client to send a remote username and password on each FTP request to a server. The username and password must be associated with an account on the FTP server. If the server has a directory structure, the configuration file or image copied from the directory is associated with the username on the server. Refer to the documentation for your FTP server for more details.

When you load a configuration file from a server using FTP, the Cisco IOS software sends the first valid username in the following list:

1. The username specified in the boot host command, if a username is specified.
2. The username set by the ip ftp username command, if the command is configured.
3. Anonymous.

The router sends the first valid password in the following list:

1. The password specified in the boot host command, if a password is specified.
2. The password set by the ip ftp password command, if the command is configured.
3. The router forms a password username @routername .domain . The variable username is the username associated with the current session, routername is the configured host name, and domain is the domain of the router.

Related Commands

To change the default name of the network configuration file from which to load configuration commands, use the boot network command in global configuration mode. To restore the network configuration filename to the default, use the no form of this command.

Syntax Description

Command Default

The default filename is network-config.

Command Modes

Global configuration

Command History

Usage Guidelines

This command instructs the system to "Boot using network configuration file x ," where x is the filename specified in the remote-url argument. This command specifies the remote location and filename of the network configuration file to be used at the next system startup, as well as the protocol to be used to obtain the file.

When booting from a network server, routers ignore routing information, static IP routes, and bridging information. As a result, intermediate routers are responsible for handling FTP, rcp, or TFTP requests. Before booting from a network server, verify that a server is available by using the ping command.

Use the service config command to enable the loading of the specified configuration file at reboot time. Without this command, the router ignores the boot network command and uses the configuration information in NVRAM. If the configuration information in NVRAM is invalid or missing, the service config command is enabled automatically.

The network server will attempt to load two configuration files from remote hosts. The first is the network configuration file containing commands that apply to all network servers on a network. Use the boot network command to identify the network configuration file. The second is the host configuration file containing commands that apply to one network server in particular. Use the boot host command to identify the host configuration file.

Note

Usually, the service config command is used in conjunction with the boot host or boot network command. You must enter the service config command to enable the router to automatically configure the system from the file specified by the boot host or boot network command. With IOS software versions 12.3(2)T , 12.3(1)B, and later, you no longer have to specify the service config command for the boot host or boot network command to be active. If you specify both the no service config command and the boot host command, the router attempts to find the specified host configuration file. The service config command can also be used without the boot host or boot network command. If you do not specify host or network configuration filenames, the router uses the default configuration files. The default network configuration file is network-confg. The default host configuration file is host-confg, where host is the hostname of the router. If the Cisco IOS software cannot resolve its hostname, the default host configuration file is router-confg.

Loading a Configuration File Using rcp

The rcp software requires that a client send the remote username on each rcp request to the network server. If the server has a directory structure (such as UNIX systems), the rcp implementation searches for the configuration files starting in the directory associated with the remote username.

When you load a configuration file from a server using rcp, the Cisco IOS software sends the first valid username in the following list:

1. The username specified in the file-URL, if a username is specified.
2. The username set by the ip rcmd remote-username command, if the command is configured.
3. The router host name.

Note	An account for the username must be defined on the destination server. If the network administrator of the destination server did not establish an account for the username, this command will not execute successfully.

Loading a Configuration File Using FTP

The FTP protocol requires a client to send a remote username and password on each FTP request to a server. The username and password must be associated with an account on the FTP server. If the server has a directory structure, the configuration file or image copied from the directory associated with the username on the server. Refer to the documentation for your FTP server for more details.

When you load a configuration file from a server using FTP, the Cisco IOS software sends the first valid username in the following list:

1. The username specified in the boot network command, if a username is specified.
2. The username set by the ip ftp username command, if the command is configured.
3. Anonymous.

The router sends the first valid password in the following list:

1. The password specified in the boot network command, if a password is specified.
2. The password set by the ip ftp password command, if the command is configured.
3. The router forms a password username @routername .domain . The variable username is the username associated with the current session, routername is the configured host name, and domain is the domain of the router.

Related Commands

To specify the system image that the router loads at startup, use one of the following boot system command in global configuration mode. To remove the startup system image specification, use the no form of this command.

Syntax Description

Command Default

If you configure the router to boot from a network server but do not specify a system image file with the boot system command, the router uses the configuration register settings to determine the default system image filename. The router forms the default boot filename by starting with the word cisco and then appending the octal equivalent of the boot field number in the configuration register, followed by a hyphen (-) and the processor type name (cisconn-cpu). Refer to the appropriate hardware installation guide for details on the configuration register and default filename. See also the config-register or confreg command.

Command Modes

Global configuration

Command History

Usage Guidelines

For this command to work, the config-register command must be set properly.

Create a comma-delimited list of several boot system commands to provide a fail-safe method for booting your router. The router stores and executes the boot system commands in the order in which you enter them in the configuration file. If you enter multiple boot commands of the same type--for example, if you enter two commands that instruct the router to boot from different network servers--the router tries them in the order in which they appear in the configuration file. If a boot system command entry in the list specifies an invalid device, the router omits that entry. Use the boot system rom command to specify use of the ROM system image as a backup to other boot system commands in the configuration.

Note	After a list of several images are specified with the boot system command, running the command again results in the list being appended, not removed.

For some platforms, the boot image must be loaded before the system image is loaded. However, on many platforms, the boot image is loaded only if the router is booting from a network server or if the flash file system is not specified. If the file system is specified, the router will boot faster because it need not load the boot image first.

This section contains the following topics:

• Changing the List of Boot System Commands
• Booting Compressed Images
• Understanding rcp
• Understanding TFTP
• Understanding FTP
• Stopping Booting and Entering ROM Monitor Mode
• Cisco 1600 Series, Cisco 3600 Series, Cisco 7000 Family, and Cisco 7600 Series Router Notes

Changing the List of Boot System Commands

To remove a single entry from the bootable image list, use the no form of the command with an argument. For example, to remove the entry that specifies a bootable image on a flash memory card inserted in the second slot, use the no boot system flash slot1: filename] command. All other entries in the list remain.

To eliminate all entries in the bootable image list, use the no boot system command. At this point, you can redefine the list of bootable images using the previous boot system commands. Remember to save your changes to your startup configuration by issuing the copy system:running-config nvram:startup-config command.

Each time you write a new software image to flash memory, you must delete the existing filename in the configuration file with the no boot system flash filename command. Then add a new line in the configuration file with the boot system flash filename command.

Note	If you want to rearrange the order of the entries in the configuration file, you must first issue the no boot system command and then redefine the list.

Booting Compressed Images

You can boot the router from a compressed image on a network server. When a network server boots software, both the image being booted and the running image must be able to fit into memory. Use compressed images to ensure that enough memory is available to boot the router. You can compress a software image on any UNIX platform using the compress command. Refer to your UNIX platform's documentation for the exact usage of the compress command. (You can also uncompress data with the UNIX uncompress command.)

Understanding rcp

The rcp requires that a client send the remote username in an rcp request to a server. When the router executes the boot system rcp command, the Cisco IOS software sends the hostname as both the remote and local usernames by default. Before the rcp can execute properly, an account must be defined on the network server for the remote username configured on the router.

If the server has a directory structure, the rcp software searches for the system image to boot from the remote server relative to the directory of the remote username.

By default, the router software sends the hostname as the remote username. You can override the default remote username by using the ip rcmd remote-username command. For example, if the system image resides in the home directory of a user on the server, you can specify that user's name as the remote username.

Understanding TFTP

You need a TFTP server running to retrieve the router image from the host.

Understanding FTP

You need an FTP server running to retrieve the router image from the host. You also need an account on the server or anonymous file access to the server.

Stopping Booting and Entering ROM Monitor Mode

During the first 60 seconds of startup, you can force the router to stop booting by pressing the Break key. The router will enter ROM monitor mode, where you can change the configuration register value or boot the router manually.

Cisco 1600 Series, Cisco 3600 Series, Cisco 7000 Family, and Cisco 7600 Series Router Notes

For the Cisco 3600 series and Cisco 7000 family, the boot system command modifies the BOOT variable in the running configuration. The BOOT variable specifies a list of bootable images on various devices.

Note

When you use the boot system command on the Cisco 1600 series, Cisco 3600 series, Cisco 7000 family, and Cisco 7600 series, you affect only the running configuration. You must save the BOOT variable settings to your startup configuration to place the information under ROM monitor control and to have the variable function as expected. Use the copy system:running-config nvram:startup-config privileged EXEC command to save the variable from your running configuration to your startup configuration.

To display the contents of the BOOT variable, use the show bootvar EXEC command.

Related Commands

The boot-start-marker and boot-end-marker flags, which can be seen in Cisco IOS software configuration files, are not CLI commands. These markers are written to configuration files automatically to flag the beginning and end of the boot commands (boot statements). By flagging boot statements, these markers allow the router to more reliably load Cisco IOS images during bootup.

A boot statement is one or more lines in a configuration file that tells the router which software image to load after a powercycling (reboot). The boot-start-marker and boot-end-marker flags will appear around any boot commands, including:

• boot bootstrap
• boot config
• boot host
• boot network
• boot system

Note, however, that these markers will always appear in the output of the show running-configor more system:running-config commands, regardless of whether any actual boot commands have been entered. This means that no boot commands will appear between the markers if no boot commands have been entered, or if all boot commands have been removed from the configuration, as shown in the "Examples" section.

The boot-start-marker and boot-end-markerflags cannot be removed or modified using the CLI. These markers are written to the startup configuration file whenever a copy running-config startup-config command is issued.

These flags were also introduced to circumvent errors in the configuration file, such as a leading space before a boot command (such as those sometimes introduced by manually edited configuration files), or the use of text strings that include the word "boot" in banners or other user-specified text.

If the "boot start-marker" flag is not found in the configuration file, the system will use the traditional method to identify the boot commands. However, if you are manually creating configuration files, or copying from older Cisco IOS software releases, the addition of these markers is recommended.

Command History

Related Commands

The boot-start-marker and boot-end-marker flags, which can be seen in Cisco IOS software configuration files, are not CLI commands. These markers are written to configuration files automatically to flag the beginning and end of the boot commands (boot statements). By flagging boot statements, these markers allow the router to more reliably load Cisco IOS images during bootup.

A boot statement is one or more lines in a configuration file that tells the router which software image to load after a powercycling (reboot). The boot-start-marker and boot-end-marker flags will appear around any boot commands, including:

• boot bootstrap
• boot config
• boot host
• boot network
• boot system

Note, however, that these markers will always appear in the output of the show running-configor more system:running-config commands, regardless of whether any actual boot commands have been entered. This means that no boot commands will appear between the markers if no boot commands have been entered, or if all boot commands have been removed from the configuration, as shown in the "Examples" section.

The boot-start-marker and boot-end-markerflags cannot be removed or modified using the CLI. These markers are written to the startup configuration file whenever a copy running-config startup-config command is issued.

These flags were also introduced to circumvent errors in the configuration file, such as a leading space before a boot command (such as those sometimes introduced by manually edited configuration files), or the use of text strings that include the word "boot" in banners or other user-specified text.

If the "boot start-marker" flag is not found in the configuration file, the system will use the traditional method to identify the boot commands. However, if you are manually creating configuration files, or copying from older Cisco IOS software releases, the addition of these markers is recommended.

Command History

Related Commands