OSPF. Neighbors on a “point-to-broadcast” network

When it comes to basic OSPF troubleshooting the first-aid kit is Neighbor states and things, that should match to form an adjacency. And on one early morning while refreshing my memory on OSPF neighbor states I accidentally ran into quite interesting problem.

But before we start, answer the short question:

Will adjacency be formed between directly connected via Gig. Ethernet interfaces routers R1 and R2 if

  • R1’s OSPF interface type configured as point-to-point
  • R2’s OSPF interface type configured as broadcast

 Time’s up. The answer is – yes and no. Wanna know why? Jump in, I have to show you something.

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