information between non-backbone areas

Stub area – this area do not accept router that belong to external autonomous system (AS). The routers in stub area use a default route to reach outside autonomous system.

Totally stubby area – This area that does not accept routes from other intra-area and default routes to be propagated within the area. If the router needs to send a packet to outside of area, it sends it using a default route.

Not-so-stubby-area– this area allows limited number of external routes that imports into area.

Types of routers

Internal router – routers that directly connected to the networks belong to the same area.

Backbone router – The router that connect with other Autonomous system bye physical or victual link.

Area border router (ABR) – A router that attached to multiple areas. ABR routers maintain the separate database for each area that connects with. Then ABR condense the topological information for their attached area and distribute to the backbone area.

Autonomous System Boundary router (ASBR) – This router have at least one interface

connect to another autonomous system.

Types of OSPF Network Topologies

Point-to-point– Two routers that directly connect each other by serial interface.

Broadcast multiaccess – Network that connects more then two routers together with broadcast capability. Such as Ethernet is a broadcast multiaccess.

Nonbroadcast multiaccess (NBMA) – Network support many routers but having no broadcast capability.

4.3.1 OSPF Command

router ospf <ospf ID> - enable OSPF in global configuration mode.

Network area - address wildcard-mask area area-id

Neighbor [poll-interval priority] - Specify a neighbor router. For point-to-Multipoint and NBMA networks, neighbor must be configured. Poll-intervalis for ospf dead-router polling interval. Priority is for ospf priority of non-broadcast neighbor.

Area – OSPF area parameters

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