Hello Again, Neighbor!
Hello from the children of planet Earth.
—Greetings to the Universe in English, message sent aboard Voyager I & II
The first step in exploring one’s area of residence is to get to know the immediate neighborhood. OSPF uses its Hello protocol as the way a router discovers and maintains its neighborly relationships across its links. As described in Chapter 9, the router sends “Hello” packets to its neighbors, and in turn receives their response “Hello” packets. This chapter undertakes a deeper study of that Hello protocol.
The OSPF Protocol Header
There are different kinds of OSPF protocol packets, but all of ...