Configuring OSPF Graceful Restart
Indeed the graceful restart refers to a way to improve network convergence when a route processor switchover is performed, either by an operator command either because primary route processor has failed. neighboring routers if capable of acting as helpers will hide the switchover from the rest of the network for X seconds after having received an LSA telling the node is performing switchover by using an opaque LSA with link local scope so that only adjacent routers receive it. you could see the opaque LSA received on a neighbor device by using appropriate debug commands. if after X seconds the local node is not come up completely or a topology change occurs in the OSPF domain the helpers will declare the local node down in OSPF.
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