27.1.1 OSPFv3 Features

OSPFv3 is typically used to route packets within a single autonomous system (AS). OSPFv3 maintains a network topology constructed from information about link states within the AS in a database on each router and uses this database to calculate shortest routes. OSPFv3 has the following advantages over RIPng:

• Less routing traffic

  OSPFv3 sends updates to other routers only when there is a change to the link state between routers. This generates far less traffic than routing protocols such as RIPng which exchange the entire routing table at fixed time intervals. In OSPFv3, each router distributes information about its own link state every 30 minutes.

• Elimination of routing loops

  Each router using OSPFv3 maintains an identical database, which it uses to select suitable routes. Therefore, unlike RIPng, OSPFv3 does not produce routing loops.

• Cost-based route selection

  When there is more than one route to a given destination, OSPFv3 selects the route with the lowest overall cost. Unlike RIPng, OSPFv3 allows route costs to be set in a flexible manner. This guarantees that the most desirable route is selected regardless of the number of hops.

• Operation of large-scale networks

  OSPFv3 can process routes whose total cost is 16777214 or less. Therefore, compared to RIPng with metrics ranging from 1 to 15, it is suitable for operation of a network with a larger route with a large number of routers.