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An alternate configuration that is saved to the switch is viewed or copied through the software currently running on the switch. This may result in a misleading portrayal of the configuration. For example, if a configuration is created on K.14.47 and saved as config2, and if it is then viewed or transferred while the switch is running K.15.01.0031, it will appear as though K.15.01.0031 has converted the configuration. However, the alternate configuration file, config2, will still be intact on the switch and load properly when the switch is booted into the same software version from which the configuration file originated.

When an enhancement introduces a feature that did not previously exist in the switch, it may present several challenges to the user.

Backwards compatibility of the configuration created with a version of software that supports a new feature or parameter is not guaranteed. Software versions that did not recognize or support a particular command or parameter will not be able to interpret that line in the configuration. For this reason, it is strongly recommended that network administrators always save their configuration while still running the switch with the original software version, and with a notation indicating the software version on which the configuration was saved. For example, a user might save a configuration for a switch running K.14.47 to a TFTP server with an IP address of 10.10.10.15 as follows:

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switch-onK1447# copy running-config tftp
10.10.10.15 5406onK1447

If, for example, the user deems it necessary to revert to the use of K.14.47, the user can boot into it and then restore the saved config from the TFTP server.

Viewing or copying an alternate configuration that is saved to the switch flash can be accomplished only with the software that is currently running on the switch.

Here, for example, a configuration is created on K.14.47 and then saved to flash:

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switch-onK1447# copy config config2 config
K1447config <cr>

And later, the configuration that was created on K.14.47 is viewed while the switch is running K.15.01.0031:

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switch-onK1501# show config K1447config <cr>

The command output will show how the K.14.47 config would be interpreted if it were to be used by the K.15.01.0031 software. Copying the K1447config file to a TFTP server would similarly trigger an interpretation by the software performing the file transfer. Note, however, that this does not actually change the configuration. If the version is rolled back from K.15.01.0031 to K.14.47 with a command like the following (given that K.14.47 is stored in secondary flash), the K.14.xx formatted config is still intact and valid.

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switch# boot system flash secondary config
K1447config

This "interpretation" during a TFTP or show command execution is inherent in the architecture of the switch. When switch features change significantly (such as the move from IPv4 support to IPv6 support), there may be configuration parameters from the previous config that cannot be translated by the switch for viewing while it is running the new software. This necessitates storing configurations for each version of software to an external location, if the user would like to view the stored config prior to reloading it.