Dell PowerEdge M520 Dell PowerConnect M6220/M6348/M8024/M8024-k CLI Referen - Page 1176

nsf helper strict-lsa-checking Use the nsf-helper strict-lsa-checking command to require that an OSPF helpful neighbor exit helper mode whenever a topology change occurs. Use the "no" form of this command to allow OSPF to continue as a helpful neighbor in spite of topology changes. Syntax nsf [ietf ] helper strict-lsa-checking no nsf [ietf ] helper strict-lsa-checking • ietf -This keyword is used to distinguish the IETF standard implementation of graceful restart from other implementations. Since the IETF implementation is the only one supported, this keyword is optional. Default Configuration A helpful neighbor exits helper mode when a topology change occurs. Command Mode Router OSPFv3 Configuration mode User Guidelines The restarting router is unable to react to topology changes. In particular, the restarting router will not immediately update its forwarding table; therefore, a topology change may introduce forwarding loops or black holes that persist until the graceful restart completes. By exiting the graceful restart on a topology change, a router tries to eliminate the loops or black holes as quickly as possible by routing around the restarting router. A helpful neighbor considers a link down with the restarting router to be a topology change, regardless of the strict LSA checking configuration. nsf restart-interval Use the nsf restart-interval command to configure the length of the grace period on the restarting router. Use the "no" form of this command to revert the grace period to its default. 1176 OSPFv3 Commands