OSPF Commands 893
nsf helper
Use the nsf-helper to allow OSPF to act as a helpful neighbor for a restarting 
router.  Use the “no” form of this command to prevent OSPF from acting as a 
helpful neighbor.
Syntax
nsf helper[ planned-only ]
no nsf helper
•
planned-only
 
— This keyword indicates that OSPF should only help a 
restarting router performing a planned restart.
Default Configuration
OSPF may act as a helpful neighbor for both planned and unplanned restarts 
Command Mode
Router OSPF Configuration mode
User Guidelines
The grace LSA announcing the graceful restart includes a restart reason. 
Reasons 1 (software restart) and 2 (software reload/upgrade) are considered 
planned restarts.  Reasons 0 (unknown) and 3 (switch to redundant control 
processor) are considered unplanned restarts. 
nsf ietf helper disable is functionally equivalent to no nsf helper and is 
supported solely for IS CLI compatibility.
Example
–
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.