Start with the big picture, follow the packets and add detail when you need it.
These guides use OSPFv2 unless stated otherwise. Start with basics, then neighbors, DR/BDR, areas and troubleshooting.
OSPF explained with dating, gossip, Mr. Krabs and memes. We go from Hello packets and neighbors to LSA1, LSA2, cost and classless routing. Because apparently this is how my brain remembers networking. Enjoy <3
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Start with reachability, interface settings and neighbor state before blaming the entire protocol.
Read guide →The backbone, an area border and an external route are three different ideas. Here is how they fit together.
Read guide →Why broadcast networks elect a DR, why the BDR matters and why 2-Way can be completely healthy.
Read guide →Down, Init, 2-Way, ExStart, Exchange, Loading and Full: follow one adjacency without panicking at every intermediate state.
Read guide →A friendly first look at Hellos, the LSDB and SPF—and why a topology map is not the same as a routing table.
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