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.
Use this command to require that an OSPF helpful neighbor exit helper mode whenever a topology change occurs.
| Default | Enabled |
| Format | nsf [ietf] helper strict-lsa-checking |
| Mode | Router OSPFv3 Config |
| Parameter | Description |
|---|---|
| ietf | This keyword is accepted but not required. |
