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Configuring Nonstop Bridging

This section includes the following topics:

Enabling Nonstop Bridging

Nonstop bridging requires you to configure graceful Routing Engine switchover (GRES). To enable graceful Routing Engine switchover, include the graceful-switchover statement at the [edit chassis redundancy] hierarchy level:

By default, nonstop bridging is disabled. To enable nonstop bridging, include the nonstop-bridging statement at the [edit protocols layer2-control] hierarchy level:

To disable nonstop active routing, remove the nonstop-bridging statement from the [edit protocols layer2–control] hierarchy level.

Synchronizing the Routing Engine Configuration

When you configure nonstop bridging, you must also include the commit synchronize statement at the [edit system] hierarchy level so that, by default, when you issue the commit command, the configuration changes are synchronized on both Routing Engines. If you issue the commit synchronize command at the [edit] hierarchy level on the backup Routing Engine, the Junos OS displays a warning and commits the candidate configuration.


A newly inserted backup Routing Engine automatically synchronizes its configuration with the primary Routing Engine configuration.

When you configure nonstop bridging, you can bring the backup Routing Engine online after the primary Routing Engine is already running. There is no requirement to start the two Routing Engines simultaneously.

Verifying Nonstop Bridging Operation

When you enable nonstop bridging, you can issue Layer 2 Control Protocol-related operational mode commands on the backup Routing Engine. However, the output of the commands might not match the output of the same commands issued on the primary Routing Engine.