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DES-7200 Configuration Guide Chapter 4 OSPF
Configuration
4-30
Command Function
DES-7200 (config)# end
Return to the privileged mode.
DES-7200# write
Save the configuration.
4.2.20 Configuring the OSPF GR
4.2.20.1 Principles of OSPF GR
OSPF GR standard:
RFC3623: Graceful OSPF Restart
RFC3623 principles:
As the standard GR protocol that IETF defines for OSPF, RFC3623 defines the
conditions, operations and precautions need to meet for the execution of Graceful
Restart. As specified in RFC3623, two GR principles are curcial. Namely, network
topology should be stable and the router can maintain the routing table during
restarting OSPF.
The execution of OSPF GR is not an independent process. Functionally, it falls
into GR Restart capability and GR Help capability. The device of GR Restart
capability can autonomously execute graceful restart, and the device of GR Help
capability can receive Grace_LSA and heop its neighbors to execue graceful
restart.
The GR Restart capability depends on products. The GR of routing protocol
generally is used to enhance the availability of the system where the control panel
and the forwarding panel are separated for continous forwarding.
The GR Help capability depends on software. If the software supports OSPF GR,
then the device is of the GR Help capability.
Generally, the device of the GR Restart capability that is executing GR is refered
to the GR Restarter, and the one of the GR Help capability that is helping the GR
Restarter to execute GR is called the GR Helper. The GR process begins by the
GR Restarter’s sending the Grace LSA. The neighbor becomes the GR Helper
upon the receipt of the Grace LSA and assists the GR Restarter to reestablish the
adjacency relation. Meanwhile, the neighbor maintains the adjacency relation with
the GR Restarter for continous data forwarding.