HP Routing Services -UX 11i v2 manual Configuring the Ospf Protocol

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Configuring the OSPF Protocol

Configuring the OSPF Protocol

Open Shortest Path First (OSPF) is a link-state routing protocol that distributes routing information between routers in a single autonomous system (AS). Each OSPF router transmits a packet with a description of its local links to all other OSPF routers. The distributed database is built from the collected descriptions. Using the database information, each router constructs its own routing table of shortest paths from itself to each destination in the AS.

OSPF allows you to organize routers, networks, and subnetworks within an AS into subsets called areas. An area is a grouping of logically contiguous networks and hosts. Instead of maintaining a topological database of the entire AS, routers in an area maintain the topology for only the area in which they reside. Therefore, all routers belonging to an area must be consistent in their configuration of the area. The topology of an area is hidden from systems that are not part of the area. The creation of separate areas can help minimize overall routing traffic in the AS. Figure 3-3 shows an example of three separate areas defined for an AS.

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