Troubleshooting

OSPF Neighbour Stuck in INIT or 2-WAY

VSVipul Sir · 6 min readLast updated: 22 July 2026

INIT means this router hears the neighbour's hellos but the neighbour does not hear ours — a one-way path, usually an ACL, a broken sub-interface, or mismatched authentication. 2-WAY on a broadcast segment is frequently normal: DROTHER routers deliberately stay 2-WAY with each other.

What you see

R1# show ip ospf neighbor
Neighbor ID     Pri   State      Dead Time   Address         Interface
2.2.2.2           1   INIT/DROTHER  00:00:34   10.0.0.2      GigabitEthernet0/0

Why it happens

INIT means hellos are flowing in one direction only. The neighbour's hello reached us, but our hello is not reaching them — or theirs does not list our router ID in its neighbour field. Common causes: an inbound ACL dropping 224.0.0.5, a unidirectional physical fault, or mismatched OSPF authentication (one side authenticating, the other not).

2-WAY is different, and this is where students waste hours: on a broadcast/multi-access network OSPF elects a DR and BDR. Every non-DR router (a DROTHER) forms a FULL adjacency only with the DR and BDR. Two DROTHERs sitting at 2-WAY with each other is correct behaviour, not a fault.

How to confirm it

show ip ospf neighbor
show ip ospf interface GigabitEthernet0/0
debug ip ospf hello
show access-lists

Check the Pri and role columns. If both routers show DROTHER and are stuck at 2-WAY, nothing is broken. If the state is INIT, look for an ACL or authentication mismatch.

The fix

! If an ACL is blocking OSPF, permit it explicitly
ip access-list extended INBOUND
 permit ospf any any
!
! If authentication is mismatched, make both sides agree
interface GigabitEthernet0/0
 ip ospf authentication message-digest
 ip ospf message-digest-key 1 md5 SECRET

If both routers are DROTHER and stuck at 2-WAY, the fix is to change nothing. If you need a full adjacency between them, raise one router's OSPF priority so it becomes DR, or use a point-to-point network type.

How to stop it happening again

Set ip ospf network point-to-point on links that only ever have two routers. It skips DR/BDR election entirely and removes this whole class of confusion.

Questions people ask

Is 2-WAY a problem?

Usually not. On broadcast networks, DROTHER routers stay at 2-WAY with each other by design and only go FULL with the DR and BDR. It is only a fault if the router should be adjacent with the DR and is not.

Why is my neighbour in INIT only on one side?

Because hellos are one-way. Your router is receiving theirs, but yours is not arriving or is being ignored. Check inbound ACLs and OSPF authentication on the neighbour.

Reading the fix is not the same as doing it

Every fault on this page can be broken and repaired on real Cisco routers and switches in our Ahmedabad lab — which is how it stops being theory. Come and see the rack before you pay anything.