Dell PowerEdge M520 Dell PowerConnect M6220/M6348/M8024/M8024-k CLI Referen - Page 1108

Default Configuration Graceful restart is disabled by default Command Mode Router OSPF Configuration mode User Guidelines Graceful restart works in concert with nonstop forwarding to enable the hardware to continue forwarding IPv4 packets using OSPFv2 routes while a backup unit takes over management unit responsibility. When OSPF executes a graceful restart, it informs its neighbors that the OSPF control plane is restarting, but that it will be back shortly. Helpful neighbors continue to advertise to the rest of the network that they have full adjacencies with the restarting router, avoiding announcement of a topology change and everything that goes with that (i.e., flooding of LSAs, SPF runs). Helpful neighbors continue to forward packets through the restarting router. The restarting router relearns the network topology from its helpful neighbors. This implementation of graceful restart restarting router behavior is only useful with a router stack. Graceful restart does not work on a standalone, single-unit router. nsf helper Use the nsf-helper to allow OSPF to act as a helpful neighbor for a restarting router. Use the "no" form of this command to prevent OSPF from acting as a helpful neighbor. Syntax nsf helper[ planned-only ] no nsf helper • planned-only - This keyword indicates that OSPF should only help a restarting router performing a planned restart. Default Configuration OSPF may act as a helpful neighbor for both planned and unplanned restarts 1108 OSPF Commands