Configuring Ospf Area Parameters - H3C S3610-28P Operation Manual

Operation Manual – IPv4 Routing
H3C S3610&S5510 Series Ethernet Switches
Note:
An OSPF process ID is unique, including the process ID for OSPF multi-instance,
which cannot be the same as any previously configured ID.
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.

3.4 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 area,
these LSAs will be translated into type 5 LSAs for advertisement to other areas.
Non-backbone areas exchange routing information via the backbone area. Therefore,
the backbone and non-backbone areas, including the backbone itself must maintain
connectivity.
If necessary physical links are not available for this connectivity maintenance, you can
configure virtual links to solve it.
3.4.1 Prerequisites
Before configuring an OSPF area, you have configured:
IP addresses for interfaces, making neighboring nodes accessible with each other
at the network layer.
OSPF basic functions.
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Chapter 3 OSPF Configuration