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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter6 Configuring Supervisor Engine Redundancy Using RPR and SSO
Understanding Supervisor Engine Redundancy Synchronization
SSO is compatible with the following list of features. However, the protocol database for these features
is not synchronized between the redundant and active supervisor engines:
•802.1Q tunneling with Layer 2 Protocol Tunneling (L2PT)
•Baby giants
•Jumbo frame support
•CDP
•Flood blocking
•UDLD
•SPAN/RSPAN
•NetFlow
The following features are learned on the redundant supervisor engine if the SSO feature is enabled:
•All Layer 3 protocols on Catalyst 4500 series switches (Switch Virtual Interfaces)
Understanding Supervisor Engine Redundancy Synchronization
During normal operation, the persistent configuration (RPR and SSO) and the running configuration
(SSO only) are synchronized by default between the two supervisor engines. In a switchover, the new
active supervisor engine uses the current configuration.
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 6-6
•SSO Supervisor Engine Configuration Synchronization, page 6-7

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 6-10.
•When the active supervisor engine detects the redundant supervisor engin e, 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 sup ervisor
engine.
•When you make changes to the configuration, you must use the write command to s ave and
synchronize the startup configuration of the redundant supervisor engine.