1166 Configuring OSPF and OSPFv3Configuring NSF Settings for OSPFBeginning in Privileged EXEC mode, use the following commands toconfigure the non-stop forwarding settings for OSPF.Command Purposeconfigure Enter global configuration mode.router ospf Enter OSPF configuration mode.nsf [ietf ] helper strict-lsa-checkingRequire that an OSPF helpful neighbor exit helper modewhenever a topology change occurs. Use the ietf keywordto distinguish the IETF standard implementation ofgraceful restart from other implementations.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 OSPF to act as a helpful neighbor for a restartingrouter. Include the planned-only keyword to indicatethat OSPF should only help a restarting routerperforming a planned restart.nsf [ietf] [planned-only] Enable a graceful restart of OSPF.• 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).
