294 CHAPTER 28: OSPF CONFIGURATION
To ensure OSPF stability, you need to decide on router IDs and configure them
manually. Any two routers in an AS must have different IDs. In practice, the ID of a
router is the IP address of one of its interfaces.
■ Enable an OSPF process
The system supports OSPF multi-process. When a router runs multiple OSPF
processes, you need to specify an ID for each process, which takes effect locally
and has no influence on packet exchange between routers. Therefore, two routers
having different process IDs can exchange packets.
■ Configure an area and specify networks in the area
The configurations for routers in an area are performed on the area basis. Wrong
configurations may cause communication failures, even routing information block
or routing loops between neighboring routers.
Follow these steps to configure OSPF basic functions:
n
■ An OSPF process ID is unique.
■ A network segment can only belong to one area.
■ It is recommended to configure a description for each OSPF process to help
identify purposes of processes and for ease of management and memorization.
■ It is recommended to configure a description for each area to help identify
purposes of areas and for ease of management and memorization.
Configuring OSPF
Area Parameters
Splitting an OSPF AS into multiple areas reduces the number of LSAs in the
networks and extends the OSPF application. For those non-backbone areas
residing on the AS boundary, you can configure them as stub areas to further
reduce the size of routing tables on routers in these areas and the number of LSAs.
A stub area cannot redistribute routes, and for this reason, NSSA was introduced.
In NSSA areas, Type-7 LSAs (NSSA External LSAs) can be advertised. Type 7 LSAs
originate from the ASBR in a NSSA area. When arriving at the ABR in the NSSA
To do… Use the command… Remarks
Enter system view system-view -
Enable OSPF and enter its view ospf [ process-id | router-id
router-id ] *
Required
Configure a description for the OSPF
process
description description Optional
Not configured by default
Configure an OSPF area and enter
OSPF area view
area area-id Required
Not configured by default
Configure a description for the area description description Optional
Not configured by default
Specify a network to enable OSPF
on the interface attached to the
network
network ip-address
wildcard-mask
Required
Not configured by default
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