Planned and Unplanned Restarts

Two types of graceful restarts are defined: planned and unplanned.

A planned restart occurs if the software module for OSPFv3 is upgraded, or if the router operator decides to restart the OSPFv3 control function for some reason. The router has advance warning, and is able to inform its neighbors in advance that OSPFv3 is restarting.

An unplanned restart occurs if there is some kind of system failure that causes a remote reboot or a crash of OSPFv3, or an MSM/MM failover occurs. As OSPFv3 restarts, it informs its neighbors that it is engaged in an unplanned restart.

You can configure a router to enter graceful restart for only planned restarts, for only unplanned restarts, or for both. Also, you can separately decide to configure a router to be a helper for only planned, only unplanned, or for both kinds of restarts.