packets, or any other OSPF protocol information from active interfaces. Passive
interfaces behave as stub networks, allowing OSPF routing devices to be aware of
devices that do otherwise participate in OSPF (either because they do not support
it, or because the administrator chooses to restrict OSPF traffic exchange or transit).
When LSAs result in changes to the routing device's LSDB, the routing device
forwards the changes to the adjacent neighbors (the DR and BDR) for distribution
to the other neighbors.
OSPF routing updates occur only when changes occur, instead of periodically. For
each new route, if a neighbor is interested in that route (for example, if configured
to receive static routes and the new route is indeed static), an update message
containing the new route is sent to the adjacency. For each route removed from the
route table, if the route has already been sent to a neighbor, an update message
containing the route to withdraw is sent.
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Chapter 35: Open Shortest Path First