Imagine this scenario:


R1's serial 1 is connected to R2's serial 1, it's a simple p2p link. Quite simple, right?

When I changed the network type on the both sides to non-broadcast, for any unreasonable reason, the adjacency dropped and everything collapsed :) I know about OSPF network types and am also well aware of the troubleshooting process. I issued almost any show/debug command; everything mostly matches on both sides: timers, area, etc. But it doesn't work, why? How do I get it working?

1 Answer 1


When you change the type to non-broadcast, you prevent the routers from multicasting their hellos (and everything else). Since they can't send hellos to each other, the adjacency drops.

As a troubleshooting hint, you should have seen that in the debugs -- OSPF was not sending hellos out that interface.

You can fix this by explicitly defining the neighbors using the neighbor statement under ospf

router ospf 1

Hellos and LSAs will be unicast to the defined neighbor.

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