SMC Networks SMC6724L3 manual 206, Configuring Network Area Addresses

CONFIGURING THE SWITCH

Configuring Network Area Addresses

OSPF protocol broadcast messages (i.e., Link State Advertisements or LSAs) are restricted by area to limit their impact on network performance. A large network should be split up into separate OSPF areas to increase network stability, and to reduce protocol traffic by summarizing routing information into more compact messages. Each router in an area shares the same view of the network topology, including area links, route summaries for directly connected areas, and external links to other areas.

Command Usage

•Use the Network Area Address Configuration page to specify an Area ID and the corresponding network address range. Each area identifies a logical group of OSPF routers that actively exchange LSAs to ensure that they share an identical view of the network topology.

•Each area must be connected to a backbone area. This area passes routing information between other areas in the autonomous system. The default value 0.0.0.0 is used as the Area ID for the backbone. All routers must be connected to the backbone, either directly, or through a virtual link if a direct physical connection is not possible.

•An area initially configured via the Network Area Address Configuration page is set as a normal area (or transit area) by default. A normal area can send and receive external Link State Advertisements (LSAs). If necessary, you can use the Area Configuration page to configure an area as a stubby area that cannot send or receive external LSAs, or a not-so-stubby area (NSSA) that can import external route information into its area

(page 3-192).

•An area must be assigned a range of subnetwork addresses. This area and the corresponding address range forms a routing interface, and can be configured to aggregate LSAs from all of its subnetwork addresses and exchange this information with other routers in the network

(page 3-196).

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