R3303-HP HSR6800 Routers Fundamentals Configuration Guide

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Using automatic configuration backup after a software
upgrade
After a software upgrade, the system by default starts up with the next-startup configuration file created
on the old software version, but the system does not load settings that are incompatible with the new
software version to the current configuration.
In case a future downgrade is needed, the system automatically checks for configuration incompatibility
and backs up the old next-startup configuration file the first time you use the save [ safely ] [ backup |
main ] [ force ] command to save the running configuration to the file.
The backup file is named in the _old-filename_bak.cfg format. For example, if the old configuration file
is named config.cfg, the backup file is named _config_bak.cfg.
In standalone mode, the overwrite and backup operations are performed on both the active MPU and
standby MPU, regardless of whether configuration auto-update is enabled.
In IRF mode, the overwrite and backup operations are performed on all MPUs in the IRF fabric,
regardless of whether configuration auto-update is enabled.
If the backup attempt fails on a standby MPU, choose one of the following failure handling actions at
prompt:
• Give up saving the configuration—The system does not save the running configuration on any
MPU.
• Overwrite the configuration file—The system uses the running configuration to overwrite the old
configuration file on the MPU without backing up the file. In standalone mode, you can copy the
backup configuration file from the active MPU to the standby MPU for future rollback. In IRF mode,
you can copy the backup configuration file from the global active MPU to a standby MPU for future
rollback.
Make sure each MPU has enough space for the backup configuration file and the new next-startup
configuration file.
To load the backup configuration file after a software downgrade, specify the backup file as the
next-startup configuration file on each MPU.
Specifying a configuration file for the next startup
You can specify a .cfg configuration file as the main startup configuration file for the next startup when
you use the save command to save the running configuration.
Alternatively, perform the following task in user view to specify a next-startup configuration file: