3.6.a Describe packet types

3.6.a [i] LSA types [1, 2, 3, 4, 5, 7, 9]

this is a great article…

OSPF route calculation overview

1) Routers establish adjacencies to flood topological information. The flooding process in OSPF is pretty complicated, and ensures the LSAs are delivered to all routers in a single area. As mentioned, topological information is carried in the form of LSAs and cannot be filtered, which it is essential to the OSPF algorithm. The only thing that limits LSA propagation is the flooding domain associated with the particular LSA type. Using the topological information learned, all routers within an area build the consistent graph of the network connections.

the rest is here:

http://blog.ine.com/2009/08/17/ospf-route-filtering-demystified/