9. Flooding

Flooding is the procedure by which a link-state protocol, such as OSPF, maintains database synchronization between routers. Database synchronization is the most crucial function in a link-state protocol. Without a synchronized database, routers might calculate incompatible routes, leading to unreachable destinations and routing loops. It is also important that flooding happen quickly, so that changes in network topology are recognized soon and so that new routes are calculated, taking the changes into account.

Figure 9.1 diagrams the flooding procedure in a single router. Flooding starts when a router receives a Link State Update packet from an adjacent neighbor. The router examines and acknowledges each LSA in the Update packet. ...

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