H3C Technologies H3C SecPath F1000-E - Manual (Page 421)

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NOTE:
•
A network segment can only belong to one area.
• H3C recommends configuring a description for each OSPF process to help identify purposes of
processes and for ease of management and memorization.
• H3C recommends configuring a description for each area to help identify purposes of areas and for
ease of management and memorization.
Configuring OSPF areas
After splitting an OSPF AS into multiple areas, you can further configure some areas as stub areas or
NSSA areas as needed.
If no connection can be achieved between the backbone and a non-backbone area, or within the
backbone itself, you can configure virtual links to solve it.
Configuration prerequisites
Before you configure an OSPF area, complete the following tasks:
• Configure IP addresses for interfaces, making neighboring nodes accessible with each other at the
network layer.
• Configure OSPF basic functions.
Configuring a stub area
You can configure a non-backbone area at the AS edge as a stub area by configuring the stub command
on all the routers attached to the area. In this way, Type-5 LSAs will not be flooded within the stub area,
reducing the routing table size. The ABR generates a default route into the stub area so that all packets
destined outside of the AS are sent through the default route.
To further reduce the routing table size and routing information exchanged in the stub area, configure it
as a totally stub area by using the stub [ no-summary ] command on the ABR. In this way, neither AS
external routes nor inter-area routing information will be distributed into the area. All the packets destined
outside of the AS or area will be sent to the ABR for forwarding.
To configure OSPF areas:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter OSPF view.
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ] * N/A
3. Enter area view. area area-id N/A
4. Configure the area as a stub
area.
stub [ default-route-advertise-always
| no-summary ]
Not configured by default.
5. Specify a cost for the default
route advertised to the stub
area.
default-cost cost
Optional.
1 by default.