OSPFv3 can continue operation without interruption during hitless failover when the NSR feature is enabled.
During graceful restart (GR), the restarting neighbors help build routing information during a failover. However, the GR helper may not be supported by all devices in a network. Non-stop routing (NSR) eliminates this dependency.
NSR does not require support from neighboring devices to perform hitless failover, and OSPF can continue operation without interruption.
Note