Command:

boot system


Mode:

Router(config)#


Syntax:

boot system file-url

no boot system file-url

boot system flash [flash-fs:][partition-number:][filename]

no boot system flash [flash-fs:][partition-number:][filename]

boot system mop filename [mac-address] [interface]

no boot system mop filename [mac-address] [interface]

boot system rom

no boot system rom

boot system {rcp | tftp | ftp} filename [ip-address]

no boot system {rcp | tftp | ftp} filename [ip-address]

no boot system


Syntax Description:

file-url

URL of the system image to load at system startup.

flash

On all platforms except the Cisco 1600 series, Cisco 3600 series, and Cisco 7000 family, this keyword boots the router from internal Flash memory. If you omit all arguments that follow this keyword, the system searches internal Flash for the first bootable image.

On the Cisco 1600 series, Cisco 3600 series, and Cisco 7000 family, this keyword boots the router from a Flash device, as specified by the device: argument. On the Cisco 1600 series and Cisco 3600 series, if you omit all optional arguments, the router searches internal Flash memory for the first bootable image. On the Cisco 7000 family, when you omit all arguments that follow this keyword, the system searches the PCMCIA slot 0 for the first bootable image.

flash-fs:

(Optional) Flash file system containing the system image to load at startup. The colon (:) is required. Valid file systems are as follows:

 

  • flash:�Internal Flash memory on the Cisco 1600 series and Cisco 3600 series. For the Cisco 1600 series and Cisco 3600 series, this file system is the default if you do not specify a file system. This is the only valid file system for the Cisco 1600 series.
  • bootflash�Internal Flash memory in the Cisco 7000 family.
  • slot0�First PCMCIA slot on the Cisco 3600 series and Cisco 7000 family. For the Cisco 7000 family, this file system is the default if you do not specify a file system.
  • slot1�Flash memory card in the second PCMCIA slot on the Cisco 3600 series and Cisco 7000 family.

 

partition-number:

(Optional) Number of the Flash memory partition that contains the system image to boot, specified by the optional filename argument. If you do not specify a filename, the router loads the first valid file in the specified partition of Flash memory. This argument is only valid on routers which can be partitioned.

filename

(Optional when used with boot system flash) Name of the system image to load at startup. It is case sensitive. If you do not specify a filename, the router loads the first valid file in the specified Flash file system, the specified partition of Flash memory, or the default Flash file system if you also omit the flash-fs: argument.

mop

Boots the router from a system image stored on a Digital MOP server. Do not use this keyword with the Cisco 3600 series or Cisco 7000 family.

mac-address

(Optional) Media Access Control (MAC) address of the MOP server containing the specified system image file. If you do not include the MAC address argument, the router sends a broadcast message to all MOP boot servers. The first MOP server to indicate that it has the specified file is the server from which the router gets the boot image.

interface

(Optional) Interface the router uses to send out MOP requests to the MOP server. The interface options are async, dialer, ethernet, serial, and tunnel. If you do not specify the interface argument, the router sends a request out on all interfaces that have MOP enabled. The interface that receives the first response is the interface the router uses to load the software.

rom

Boots the router from ROM. Do not use this keyword with the Cisco 3600 series or the Cisco 7000 family.

rcp

Boots the router from a system image stored on a network server using rcp.

tftp

Boots the router from a system image stored on a TFTP server.

ftp

Boots the router from a system image stored on an FTP server.

ip-address

(Optional) IP address of the server containing the system image file. If omitted, this value defaults to the IP broadcast address of 255.255.255.255.

 


Command Description:

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

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

Enter 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. For example, if you enter two commands that instruct the router to boot from different network servers, the router will execute 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 skips that entry. Use the boot system rom command to specify use of the ROM system image as a backup to other boot commands in the configuration.

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 does not have to load the boot image first.

This section contains the following usage guideline sections:

 

 

Change 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.


Boot 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 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.)

Understand the rcp Protocol

The rcp protocol requires a client to 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 host name as both the remote and local usernames by default. For the rcp protocol to 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 host name 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.

Understand TFTP

You need a TFTP server running in order to fetch the router image from the host.

Understand FTP

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

Stop Booting and Enter 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, and Cisco 7000 family notes

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


 

Note   When you use the boot system global configuration command on the Cisco 1600 series, Cisco 3600 series, and Cisco 7000 family, you affect only the running configuration. You must save the BOOT environment variable settings 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.


To view the contents of the BOOT environment variable, use the show bootenv command.

Example:

Router(config)#boot system ftp cz2600-120tomz.bin 10.0.0.2


Misconceptions:

 

None


Related Commands:

 

None

 


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