Configuring OSPFv3 GR

GR ensures forwarding continuity when a routing protocol restarts or an active/standby switchover occurs:

Two routers are required to complete a GR process. The following are router roles in a GR process.

• GR restarter—Graceful restarting router. It must be Graceful Restart capable.

• GR helper—The neighbor of the GR restarter. It helps the GR restarter to complete the GR process.

To prevent service interruption after a master/backup switchover, a GR restarter running OSPFv3 must complete the following tasks:

• Keep the GR restarter forwarding entries stable during reboot.

• Establish all adjacencies and obtain complete topology information after reboot.

After the active/standby switchover, the GR restarter sends a Grace LSA to tell its neighbors that it performs a GR. Upon receiving the Grace LSA, the neighbors with the GR helper capability enter the helper mode (and are called "GR helpers"). Then, the GR restarter retrieves its adjacencies and LSDB with the help of the GR helpers.