Chapter 5
Configuring RPR and RPR+ Supervisor Engine Redundancy
RPR+ enhances RPR by providing the following additional benefits:
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The following events cause an RPR+ switchover:
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Supervisor Engine Synchronization
During RPR mode operation, the startup-config and config-registers configuration are synchronized by
default between the two supervisor engines. In a switchover, the new active supervisor engine uses the
current configuration.
Note
Unless auto-synchronization has been disabled, the boot variables are synchronized by default.
When a redundant supervisor engine configuration is running in RPR+ mode, the following operations
trigger synchronization:
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Reduced switchover time
Depending on the configuration, the switchover time is in the range of 30 to 60 seconds.
Installed modules are not reloaded
Because both the startup configuration and the running configuration are continually synchronized
from the active to the redundant supervisor engine, installed modules are not reloaded during a
switchover.
Online insertion and removal (OIR) of the redundant supervisor engine
RPR+ allows OIR of the redundant supervisor engine for maintenance. When the redundant
supervisor engine is inserted, the active supervisor engine detects its presence and begins to
transition the redundant supervisor engine to fully initialized state.
Synchronization of OIR events
Manual user-initiated switchover using the redundancy force-switchover command
Clock synchronization failure between supervisor engines
MSFC or PFC failure on the active supervisor engine
When a redundant supervisor engine first comes online, the configuration information is
synchronized in bulk from the active supervisor engine to the redundant supervisor engine. This
synchronization overwrites any existing startup configuration file on the redundant supervisor
engine.
When configuration changes occur during normal operation, RPR+ performs an incremental
synchronization from the active supervisor engine to the redundant supervisor engine. RPR+
synchronizes user-entered CLI commands incrementally line-by-line from the active supervisor
engine to the redundant supervisor engine.
Even though the redundant supervisor engine is fully initialized, it only interacts with the active
supervisor engine to receive incremental changes to the configuration files as they occur. You cannot
enter CLI commands on the redundant supervisor engine.
Synchronization of the startup configuration file is enabled by default in RPR+ mode.
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
Understanding Supervisor Engine Redundancy
5-3