990 Configuring OSPF and OSPFv3Configuring NSF Settings for OSPFv3Beginning in Privileged EXEC mode, use the following commands toconfigure the non-stop forwarding settings for OSPFv3.Command Purposeconfigure Enter global configuration mode.ipv6 router ospf Enter OSPFv3 configuration mode.nsf [ietf ] helper strict-lsa-checkingRequire that an OSPFv3 helpful neighbor exit helpermode whenever a topology change occurs. Use the ietfkeyword to distinguish the IETF standardimplementation of graceful restart from otherimplementations.nsf [ietf ] restart-intervalsecondsConfigure the length of the grace period on the restartingrouter.Theseconds keyword is the number of seconds that therestarting router asks its neighbors to wait before exitinghelper mode. The restarting router includes the restartinterval in its grace LSAs (range 1–1800 seconds)nsf helper [planned-only] Allow OSPFv3 to act as a helpful neighbor for a restartingrouter. Include the planned-only keyword to indicatethat OSPFv3 should only help a restarting routerperforming a planned restart.nsf [ietf] [planned-only] Enable a graceful restart of OSPFv3.• ietf — This keyword is used to distinguish the IETFstandard implementation of graceful restart from otherimplementations. Since the IETF implementation isthe only one supported, this keyword is optional.• planned-only — This keyword indicates that OSPFshould only perform a graceful restart when the restart isplanned (i.e., when the restart is a result of the initiatefailover command).
