# Guidelines for Activating High Availability

Before you activate high availability on the line modules, you must be aware of any high availability–related changes to line module management commands. For information on high availability-related changes to SRP modules, see Managing Stateful SRP Switchover.

You activate high availability (stateful line module switchover) by launching Redundancy Configuration mode and issuing the mode high-availability slot command. The high-availability slot keyword enables high availability mode for stateful line module switchover. In this mode, the router uses mirroring to keep the configuration and state of the standby line module coordinated with the configuration and state of the active line module.

When activating high availability, keep the following in mind:

- In an E120 router and an E320 router that supports stateful line module switchover, both line modules must be running the same software release version in order to activate high availability mode.
- If high availability mode cannot become active because of unsafe configuration on the active and standby line modules, the system reverts to its default mode (redundancy configuration).
- When active, the router configuration files are mirrored from the active line module to the standby line module.

#### Related Documentation

- Activating High Availability
- Deactivating High Availability
- Guidelines for Deactivating High Availability
- mode
- line-card switch
- show redundancy history
- show redundancy line-card