Reference Guide

642 | Open Shortest Path First (OSPFv2 and OSPFv3)
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• grace period—the length of time the graceful restart process can last before OSPF terminates it.
•
helper-reject neighbors—the router ID of each restart router that does not receive assistance from the
configured router.
•
mode—the situation or situations that trigger a graceful restart.
•
role—the role or roles the configured router can perform.
You enable OSPFv2 graceful restart in CONFIGURATION ROUTER OSPF mode.
When you configure a graceful restart on an OSPFv2 router, the
show run ospf command (Figure 29-17)
displays information similar to the following.
Note: By default, OSPFv2 graceful restart is disabled.
Command Syntax Command Mode Usage
graceful-restart
grace-period
seconds
CONFIG-ROUTER-
OSPF-id
Enable OSPFv2 graceful-restart globally and set the grace period.
Seconds range: between 40 and 3000.
This is the period of time that an OSPFv2 router’s neighbors will advertise it as fully
adjacent, regardless of the synchronization state, during a graceful restart.
OSPFv2 terminates this process when the grace period ends.
graceful-restart
helper-reject router-id
CONFIG-ROUTER-
OSPF-id
Enter the Router ID of the OSPFv2 helper router from which the
router does not accept graceful restart assistance.
This applies to the specified router only.
IP Address: A.B.C.D
graceful-restart mode
[planned-only |
unplanned-only]
CONFIG-ROUTER-
OSPF-id
Specify the operating mode in which graceful-restart functions.
FTOS supports the following options:
• Planned-only. The OSPFv2 router supports graceful-restart for
planned restarts only. A planned restart is when the user
manually enters a fail-over command to force the primary
RPM over to the secondary RPM. During a planned restart,
OSPF sends out a Grace LSA before the system switches over
to the secondary RPM. OSPF also is notified that a planned
restart is happening.
• Unplanned-only. The OSPFv2 router supports graceful-restart
for only unplanned restarts. During an unplanned restart, OSPF
sends out a Grace LSA once the secondary RPM comes online.
By default, OSPFv2 supports both planned and unplanned restarts. Selecting one or the
other mode restricts OSPFv2 to the single selected mode.
graceful-restart role
[helper-only | restart-only]
CONFIG-ROUTER-
OSPF-id
Configure the graceful restart role or roles that this OSPFv2 router
performs. FTOS supports the following options:
• Helper-only. The OSPFv2 router supports graceful-restart only
as a helper router.
• Restart-only. The OSPFv2 router supports graceful-restart only
during unplanned restarts.
By default, OSPFv2 supports both restarting and helper roles. Selecting one or the other role
restricts OSPFv2 to the single selected role.