Ospf Area Attribute Configuration - H3C S7500 Series Operation Manual

Operation Manual – Routing Protocol
H3C S7500 Series Ethernet Switches
Configure the network
segments in the area
Note:
The undo protocol multicast-mac enable command must be configured if Layer
2/Layer 3 multicast function is enabled in the system.
In router ID selection, the priorities of the router IDs configured with the ospf
[ process-id [ router-id router-id ] ] command, the router id command, and the
priorities of the router IDs automatically selected are in a descending order.
Router IDs can be re-selected. A re-selected router ID takes effect only after the
OSPF process is restarted.
The ospf [ process-id [ router-id router-id ] ] command is recommended for
configuring router IDs manually.
The ID of an OSPF process is unique.
A segment can belong to one area only and you must specify each OSPF interface
to belong to a particular area.

4.4 OSPF Area Attribute Configuration

Area partition in OSPF reduces the number of LSAs in the network and enhances
OSPF scalability. To further reduce routing table size and the number of LSAs in some
non-backbone areas on the edge of the AS, you can configure these areas as stub
areas.
A stub area cannot import any external route. For this reason the concept of NSSA
area is introduced. Type7 LSAs can be advertised in an NSSA area. Type7 LSAs are
generated by ASBRs of the NSSA area, and will be transformed into AS-external
LSAs whey reaching ABRs in the NSSA area, which will then be advertised to other
areas.
After area partition, the OSPF route updates between non-backbone areas are
exchanged by way of the backbone area. Therefore, OSPF requires that all the
non-backbone areas should keep connectivity with the backbone area and the
backbone area must keep connectivity in itself.
If the physical connectivity cannot be ensured due to various restrictions, you can
configure OSPF virtual links to satisfy this requirement.
To do... Use the command...
network address
wildcard-mask
Required
By default, an interface does not
belong to any area.
4-11
Chapter 4 OSPF Configuration
Remarks