Cisco CRS-1 - Carrier Routing System Router Migration Manual page 28

Upgrading to Cisco IOS XR Software Release 4.0.X(PX) Before Migrating to Cisco CRS-3 Hardware
Also refer to the "Other Firmware Support" section in the Release Notes for Cisco CRS-1 and Cisco
CRS-3 for Cisco IOS XR Software Release 4.0.2 document which can be accessed at:
http://www.cisco.com/en/US/docs/routers/crs/software/crs_r4.0/general/release/notes/reln_402crs.html
Caveats:
During software upgrade or downgrade, the system could detect incompatible configuration and remove
it from the running configuration. The removed configuration will be saved to a file on the router. A
configuration could also fail due to syntax or semantic error as the router boots the new version of the
software.
To resolve these issues, you must browse the removed or failed configuration and then address the
changes so that the configuration can be properly applied on the new version of software.
Addressing Incompatible and Removed Configurations
During the test activation of a new software version, incompatible configurations will be identified and
removed from the router running configuration. Syslog and console logs will provide the necessary
information on the name of the removed configuration file. To address the incompatible configuration,
you should browse the removed configuration file, address the syntax and semantics errors and re-apply
the config as required and/or applicable after upgrade.
To display the removed configuration, execute the following command from exec mode:
Addressing Failed Admin and Non-Admin Configurations During Reload
Some configuration may fail to take effect when the router boots with the new software. These
configurations will be saved as failed configurations. During activation of the new software version, you
will be notified via syslog and console log if a configuration failed to take effect. To address the failed
configuration, you should browse both the admin and non-admin failed configurations, address any
syntax and semantics errors found, and then re-apply it as required.
To display the failed configuration, execute the following commands:
MDR - Minimum Disruption Restart
The MDR (Minimum Disruption Restart) feature is not supported for upgrades to the
Cisco IOS XR software 4.0.0.T, Cisco IOS XR software 4.0.1, or Cisco IOS XR software 4.0.2 releases.
Limitations With the Preconfig Interface
It is important that you check to see whether the persistent config and the running config are the same
or different. If they are different then it will have a problem after reload/upgrade, because reload/upgrade
will use the persistent config to restore configuration and the restored configuration will be different
from the one you were running.
Execute the following commands to verify that the persistent config and the running config are the same:
show cfgmgr persistent-config - shows the persistent config in CLI form
show running-config - shows running config
Cisco CRS-1 Carrier Routing System to Cisco CRS-3 Carrier Routing System Migration Guide
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router# show configuration removed <removed config filename>
router# show configuration failed startup
router(admin)# show configuration failed startup
Chapter 1 Migrating to a Cisco CRS-3 Carrier Routing System
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