Provides configuration guidelines for physical interface preconfiguration, including verification, dual-Route Processor behavior, and saving preconfigured changes.
These guidelines apply for physical interface preconfiguration:
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When you plug the anticipated line card in the router, ensure that you verify any preconfiguration setting by using the appropriate show commands.
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We recommend filling out preconfiguration information in your site planning guide. This allows you to compare the anticipated configuration with the actual preconfigured interfaces when you install the line card and the interfaces are up.
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You do not need to configure anything to guarantee that the standby interface configurations are maintained.
Active and standby RPs and virtual interface guidelines
The standby RP is available and is in a state in which it can take the load from an active RP if required. The standby RP becomes active when:
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failure is detected by a watchdog
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it is administratively commanded to take over
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the active RP is removed from the router
If a second RP is not present in the chassis while the first is in operation, the system may insert a second RP. The second RP then automatically becomes the standby RP. The standby RP may also be removed from the chassis with no effect on the system other than loss of RP redundancy.
After failover, the virtual interfaces become available on the standby, which is now active. Their state and configuration is unchanged, and there is no loss of forwarding, in the case of tunnels, during the failover. The routers use nonstop forwarding over tunnels through the failover of the host RP.
Use the show run command to see the interfaces that are in the preconfigured state.
In a dual RP system, the interface state sync library monitors the state between active and standby RPs. An alarm is raised when a port is down on one RP and the same port is up on the other RP.
Use the commit best-effort command to save the preconfiguration to the running configuration file. The commit best-effort command merges the target configuration with the running configuration and commits only the valid configuration (best effort). Some configuration might fail due to semantic errors, but the valid configuration still comes up.
Clear the alarm when there is no inconsistency between both RP port states.
If behavior deviates, review the preconfiguration, verify interface state on both RPs, and align the configuration with this principle.