Cisco Systems 4500 Supervisor Engine Redundancy Guidelines and Restrictions

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Software Configuration Guide—Release 15.0(2)SG
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Chapter 8 Configuring Supervisor Engine Redundancy Using RPR and SSO Supervisor Engine Redundancy Guidelines and Restrictions
Note You cannot enter CLI commands on the redundant supervisor engine console.
These sections describe supervisor engine redundancy synchronization:
• RPR Supervisor Engine Configuration Synchronization, page 8-5
• SSO Supervisor Engine Configuration Synchronization, page 8-5
RPR Supervisor Engine Configuration Synchronization
Because the redundant supervisor engine is only partially initialized in RPR mode, it interacts with the
active supervisor engine only to receive configuration changes at startup and upon saving the
configuration changes.
When a redundant supervisor engine is running in RPR mode, the following events trigger
synchronization of the configuration information:
• When the redundant supervisor engine boots, the auto-sync command synchronizes the persistent
configuration. This command is enabled by default. For details, refer to “Synchronizing the
Supervisor Engine Configurations” section on page 8-11.
• When the active supervisor engine detects the redundant supervisor engine, the configuration
information is synchronized from the active supervisor engine to the redundant supervisor engine.
This synchronization overwrites any existing startup configuration file on the redundant supervisor
engine.
• When you make changes to the configuration, you must use the write command to save and
synchronize the startup configuration of the redundant supervisor engine.
SSO Supervisor Engine Configuration Synchronization
When a redundant supervisor engine runs in SSO mode, the following events trigger synchronization of
the configuration information:
• When the active supervisor detects the redundant supervisor engine, synchronization of the
persistent and running configuration takes place, allowing the redundant supervisor engine to arrive
at a fully-initiated state.
• When real-time changes occur, the active supervisor engine synchronizes the running-config and
(or) the persistent configuration (if necessary) with the redundant supervisor engine.
• When you change the configuration, you must use the write command to allow the active supervisor
engine to save and synchronize the startup configuration of the redundant supervisor engine.
Supervisor Engine Redundancy Guidelines and Restrictions
The following guidelines and restrictions apply to supervisor engine redundancy:
• If SSO mode cannot be established between the active and standby supervisor engines because of
an incompatibility in the configuration file, a mismatched command list (MCL) is generated at the
active supervisor engine and a reload into RPR mode is forced for the standby supervisor engine.
Subsequent attempts to establish SSO, after removing the offending configuration and rebooting the
standby supervisor engine with the exact same image, might cause the