It all started with this message. Tun0 interface has always been up and connectivity has been verified.
*Apr 17 15:26:13.312: %OSPF-5-ADJCHG: Process 302, Nbr184.108.40.206 on Tunnel0 from FULL to DOWN, Neighbor Down: Interface down or detached
debug ip ospf packet
*Apr 17 15:38:23.938: OSPF-302 PAK Tu0: Drop packet, OSPF shut down on interface
CE2#show ip ospf int tun0 Tunnel0 is up, line protocol is up Internet Address 220.127.116.11/24, Area 51, Attached via Interface Enable Process ID 302, Router 18.104.22.168, Network Type BROADCAST, Cost: 1000 Topology-MTID Cost Disabled Shutdown Topology Name 0 1000 no no Base Enabled by interface config, including secondary ip addresses Transmit Delay is 1 sec, State DOWN, Priority 0 No designated router on this network No backup designated router on this network Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 oob-resync timeout 40
I am unable to find anything about "Drop packet, OSPF shut down on interface". Known bug?