ospf point to point neighbors

[MAHI_VYAS]

Hello All,

I have 3 ospf point to point routers  connected with switch in between.

I observed only 2 routers can form neighborship at the time, example R1 can form neighbor with R2 or R3 at the time.

Can anyone explain why this behaviour.

Find the attached topology.

[MHM Cisco World]

This design not work as p2p ypu need to use p2mp

MHM

[Torbjørn · Accepted solution]

The point-to-point network type is limited to a single neighbor per link/interface, while point-to-multipoint allows for multiple adjacencies to form as @MHM Cisco World is describing. That said I would use the broadcast network type for the topology above.

[M02@rt37]

Hello @MAHI_VYAS 

see here: https://ipcisco.com/lesson/ospf-network-types-ccnp/

[Joseph W. Doherty]

I have 3 ospf point to point routers  connected with switch in between.

If they are all in the same L2 broadcast domain, and all using IPs in the same subnet, you do NOT have a p2p, physically or logically.  P2p is limited to a pair.

As the others have indicated, for your 3 routers you would not use an OSPF p2p.  Although, if you only had two routers, you optionally could.