OSPF Neighbor Stuck in INIT State: FortiGate Troubleshooting

OSPF neighbors pass through Down → Attempt → INIT → 2-Way → ExStart → Exchange → Loading → Full on the way to a working adjacency — and the state where troubleshooting most often stalls is INIT. A neighbor stuck in INIT means your router is receiving HELLO packets from the peer, but the peer is not receiving yours. This article explains the INIT state, the handful of causes behind it, and the FortiGate commands that pinpoint which one you are dealing with.

What INIT Means

OSPF uses multicast 224.0.0.5 (AllSPFRouters) to send HELLOs. If the multicast packets are dropped between source and destination, the peer never sees your HELLO and stays in INIT — a one-way relationship. Common causes: MTU mismatch, HELLO drops, authentication configured on only one side, or a firewall blocking protocol 89.

Diagnostic Commands on FortiGate

get router info ospf interface
get router info ospf neighbor

On the OSPF interface output, check the counters:

Internet Address 192.168.X.Y/30, Area 0.0.0.0, MTU 1500
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello received 14467 sent 75124, DD received 780 sent 906   <-- HELLOs are being dropped
** Cryptographic authentication enabled **                    <-- auth mismatch possible

Compare MTU on both routers (make them equal or ignore MTU), verify HELLO counters on both sides, and confirm authentication is configured identically on both peers.

Sniffer Verification

Confirm whether HELLOs are actually leaving and arriving:

diagnose sniffer packet any "proto 89" 4 0 a
diagnose sniffer packet any "host 224.0.0.5" 4

If you see only outbound HELLOs (1-way), fix the drop or switch to unicast OSPF — set the network type to non-broadcast and specify the neighbor manually.

Related Reading

For more FortiGate operational commands see FortiGate FortiOS CLI 排障速查; for BGP adjacency debugging on Junos see Junos BGP 建立排障.

原文链接：https://community.fortinet.com/t5/FortiGate/Troubleshooting-Note-OSPF-Neighbor-stuck-in-INIT-state/ta-p/204002