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Cisco IE 2000 Switch Software Configuration Guide
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Appendix A Working with the Cisco IOS File System, Configuration Files, and Software Images
Working with Configuration Files
The Cisco IOS configuration archive, in which the configuration files are stored and available for use
with the configure replace command, is in any of these file systems: FTP, HTTP, RCP, TFTP.

Replacing a Configuration

The configure replace privileged EXEC command replaces the running configuration with any saved
configuration file. When you enter the configure replace command, the running configuration is
compared with the specified replacement configuration, and a set of configuration difference s is
generated. The resulting differences are used to replace the configuration. The configuration
replacement operation is usually completed in no more than three passes. To prevent looping behavior
no more than five passes are performed.
You can use the copy source-url running-config privileged EXEC command to copy a stored
configuration file to the running configuration. When using this command as an alternative to the
configure replace target-url privileged EXEC command, note these major differences:
• The copy source-url running-config command is a merge operation and preserves all the commands
from both the source file and the running configuration. This command does not remove commands
from the running configuration that are not present in the source file. In contrast, the configure
replace target-url command removes commands from the running configuration that are not pre sent
in the replacement file and adds commands to the running configuration that are not present.
• You can use a partial configuration file as the source file for the copy source-url running-config
command. You must use a complete configuration file as the replacement file for the configure
replace target-url command.

Rolling Back a Configuration

You can also use the configure replace command to roll back changes that were made since the previous
configuration was saved. Instead of basing the rollback oper ation on a specific set of changes that were
applied, the configuration rollback capability reverts to a specific configuration based on a saved
configuration file.
If you want the configuration rollback capability, you must first save the running configuration before
making any configuration changes. Then, after entering configurat ion changes, you can use that saved
configuration file to roll back the changes by using the configure replace target-url command.
You can specify any saved configuration file as the rollback configuration. You are not limited to a fixed
number of rollbacks, as is the case in some rollback model s.
Configuration Guidelines
Follow these guidelines when configuring and performing configuration replacement and rollba ck:
• Make sure that the switch has free memory larger than the combined size of the two configuration
files (the running configuration and the saved replacement configuration). Othe rwise, the
configuration replacement operation fails.
• Make sure that the switch also has sufficient free memory to execute the configuration replacement
or rollback configuration commands.
• Certain configuration commands, such as those pertaining to physical com ponents of a networking
device (for example, physical interfaces), cannot be added or rem oved from the running
configuration.
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A configuration replacement operation cannot remove the interface interface-id command line
from the running configuration if that interface is physically present on the device.