The netmask doesn't match between neighbors R1# OSPF: Mismatched hello parameters from 192.168.12.2 OSPF: Dead R 40 C 40, Hello R 10 C 10 Mask R 255.255.255.128 C 255.255.255.0 Now we have something to work with. R1 says it received a hello packet but we have mismatched hello parameters. The R stands for what we received and the C stands for what we have configured. You can see that there is a mismatch in the subnet mask. R1 is configured with subnet mask 255.255.255.0 while R2 has subnet mask 255.255.255.240. OSPF will only compare the subnet mask when you are using the broadcast network type. You can also spot this error if you look at the OSPF information per interface. Broadcast is using a DR router while point-to-point doesn't use a DR router.