When a redundant supervisor engine is in standby mode, the two Gigabit Ethernet interfaces on the standby supervisor engine are always active.
Supervisor engine redundancy does not provide supervisor engine mirroring or supervisor engine load balancing. Only one supervisor engine is active.
Configuration changes made through SNMP are not synchronized to the standby supervisor engine. After you configure the switch through SNMP, copy the running-config file to the startup-config file on the active supervisor engine to trigger synchronization of the startup-config file on the standby supervisor engine.
Supervisor engine switchover takes place after the failed supervisor engine completes a core dump. A core dump can take up to 15 minutes. To get faster switchover time, disable core dump on the supervisor engines.
You cannot perform configuration changes during the startup (bulk) synchronization. If you attempt to make configuration changes during this process, the following message is generated:
Config mode locked out till standby initializes
If configuration changes occur at the same time as a supervisor engine switchover, these configuration changes are lost.
Hardware Restrictions for RPR
Cisco IOS supports redundant configurations where the supervisor engines are identical. If they are not identical, one will boot first and become active and hold the other supervisor engine in a reset condition.
Each supervisor engine must have the resources to run the switch on its own, which means all supervisor engine resources are duplicated, including all flash devices.
Make separate console connections to each supervisor engine. Do not connect a Y cable to the console ports.
When the switch is powered on, RPR runs between the two supervisor engines. The supervisor engine that boots first becomes the RPR active supervisor engine. The route processor (RP) and Policy Feature Card (PFC) become fully operational. The RP and PFC on the standby supervisor engine come out of reset but are not operational.
In a switchover, the standby supervisor engine become fully operational and the following occurs:
All switching modules power up again
Remaining subsystems on the RP (including Layer 2 and Layer 3 protocols) are brought up
Access control lists (ACLs) are reprogrammed into supervisor engine hardware
Note In a switchover, there is a disruption of traffic because some address states are lost and then restored after they are dynamically redetermined.
Supervisor Engine Configuration Synchronization
Note Configuration changes made through SNMP are not synchronized to the standby supervisor engine. After you configure the switch through SNMP, copy the running-config file to the startup-config file on the active supervisor engine to trigger synchronization of the startup-config file on the standby supervisor engine.
During RPR mode operation, the startup-config files and the config-register configurations are synchronized by default between the two supervisor engines. In a switchover, the new active supervisor engine uses the current configuration.
Configures RPR. When this command is entered, the standby supervisor engine is reloaded and begins to work in RPR mode.
This example shows how to configure the system for RPR:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config-red)# mode rpr
Router# show running-config
Router# show redundancy states
Synchronizing the Supervisor Engine Configurations
During normal 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 Do not change the default auto-sync configuration.
Displaying the Redundancy States
To display the redundancy states, perform this task:
Router# show redundancy states
Displays the redundancy states.
This example shows how to display the redundancy states: