Classified as: {Hitachi Rail – Public} My setup : Linux running bird， Peer: Fortinet Firewall In bird, configure bfd as below: protocol bfd BFD_SD_01 { interface "*" { min rx interval 1000000 us; min tx interval 1000000 us; idle tx interval 1000000 ums; multiplier 3; }; neighbor 192.168.0.1 local 192.168.0.2; } Fortinet side, biasally same, also set rx intrva: 1000 ms, tx interval: 1000ms, multiplier: 3 However, both side show bfd DOWN。 Catpure tcpdump in Fortinet side, Fortinet IP: 192.168.0.1 Time source destination protocol info 1 0.000000 192.168.0.2 192.168.0.1 BFD Control Diag: No Diagnostic, State: Down, Flags: 0x00 6 0.756375 192.168.0.2 192.168.0.1 BFD Control Diag: No Diagnostic, State: Down, Flags: 0x00 11 1.519796 192.168.0.2 192.168.0.1 BFD Control Diag: No Diagnostic, State: Down, Flags: 0x00 14 2.351177 192.168.0.2 192.168.0.1 BFD Control Diag: No Diagnostic, State: Down, Flags: 0x00 19 3.225686 192.168.0.2 192.168.0.1 BFD Control Diag: No Diagnostic, State: Down, Flags: 0x00 24 3.852938 192.168.0.1 192.168.0.2 BFD Control Diag: Control Detection Time Expired, State: Down, Flags: 0x00 25 3.981126 192.168.0.2 192.168.0.1 BFD Control Diag: No Diagnostic, State: Down, Flags: 0x00 from Fortinet neighbour information, it seems cannot receive control message from Peer, why? I don't have any block port. Why get detection time: 1500ms after neighboation Below is fortinet bfd neighbor information OurAddress NeighAddress State Interface LDesc/RDesc 192.168.0.1 192.168.0.2 DOWN STN2-SD-A 1/0/M Local Diag: 1, Demand mode: no, Poll bit: unset MinTxInt: 1000, MinRxInt: 1000, Multiplier: 3 Received: MinRxInt: 0 (ms), MinTxInt: 0 (ms), Multiplier: 3 Transmit Interval: 6500 (ms), Detection Time: 1500 (ms) Rx Count: 0, Rx Interval; (ms) min/max/avg 0/0/0 Tx Count: 10287, Tx Interval (ms) min/max/avg 5000/5030/5000, last: 2350 (ms) ago Registered protocols: Static BGP Is this bird issue or fortinet? I suspect 80% caused by Fortiet, but I just want to get some suggestion/proposal from bird expert. With Best Regards, Chris LIU Hitachi Rail – Public {Hitachi Rail – Public}