Command Reference Guide

Open Shortest Path First Commands
CLI Command Reference
September 2014 Page 583
HP Moonshot Switch Module CLI Command Reference
OSPF Graceful Restart Commands
The OSPF protocol can be configured to participate in the checkpointing service, so that these protocols can
execute a “graceful restart” when the management unit fails. In a graceful restart, the hardware to continues
forwarding IPv4 packets using OSPF routes while a backup switch takes over management unit responsibility
Graceful restart uses the concept of “helpful neighbors”. A fully adjacent router enters helper mode when it
receives a link state announcement (LSA) from the restarting management unit indicating its intention of
performing a graceful restart. In helper mode, a switch continues to advertise to the rest of the network that
they have full adjacencies with the restarting router, thereby avoiding announcement of a topology change and
the potential for flooding of LSAs and shortest-path-first (SPF) runs (which determine OSPF routes). Helpful
neighbors continue to forward packets through the restarting router. The restarting router relearns the
network topology from its helpful neighbors.
Graceful restart can be enabled for either planned or unplanned restarts, or both. A planned restart is initiated
by the operator through the management command
initiate failover. The operator may initiate a failover
in order to take the management unit out of service (for example, to address a partial hardware failure), to
correct faulty system behavior which cannot be corrected through less severe management actions, or other
reasons. An unplanned restart is an unexpected failover caused by a fatal hardware failure of the management
unit or a software hang or crash on the management unit.
nsf
Use this command to enable the OSPF graceful restart functionality on an interface. To disable graceful restart,
use the no form of the command.
no nsf
Use this command to disable graceful restart for all restarts.
Default Disabled
Format
nsf [ietf] [planned-only]
Modes OSPF Router Configuration
Parameter Description
ietf This keyword is accepted but not required.
planned-only This optional keyword indicates that OSPF should only perform a graceful restart when the
restart is planned (i.e., when the restart is a result of the initiate failover command).