Good morning, we have one server on which all bfd sessions are down, however the associated BGP protocols are actually up: bird> show bfd sessions bfd1: IP address Interface State Since Interval Timeout 2a0a:e5c0:10:1::122 eth0 Down 11:49:53.211 2.000 0.000 2a0a:e5c0:31:12::1 oserver120 Down 10:54:30.465 1.000 0.000 2a0a:e5c0:10:1::123 eth0 Down 11:59:53.890 2.000 0.000 bfd2: IP address Interface State Since Interval Timeout bird> bird> show protocols outgoing_server120 Name Proto Table State Since Info outgoing_server120 BGP --- up 10:54:35.058 Established bird> bird> show protocols ibgp_server122 Name Proto Table State Since Info ibgp_server122 BGP --- up 11:54:09.411 Established bird> show protocols ibgp_server123 Name Proto Table State Since Info ibgp_server123 BGP --- up 11:59:55.306 Established bird> The log of bird says: 2024-06-18 12:18:30.095 <RMT> bfd2: Bad packet from 2a0a:e5c0:10:1::123 - unknown session id (4057542731) 2024-06-18 12:18:30.288 <RMT> bfd2: Bad packet from 2a0a:e5c0:31:12::1 - unknown session id (1148668725) 2024-06-18 12:18:30.434 <RMT> bfd2: Bad packet from 2a0a:e5c0:10:1::122 - unknown session id (635122417) 2024-06-18 12:18:30.912 <RMT> bfd2: Bad packet from 2a0a:e5c0:10:1::123 - unknown session id (4057542731) 2024-06-18 12:18:31.058 <RMT> bfd2: Bad packet from 2a0a:e5c0:31:12::1 - unknown session id (1148668725) 2024-06-18 12:18:31.230 <RMT> bfd2: Bad packet from 2a0a:e5c0:10:1::122 - unknown session id (635122417) It seems like declaring 2 bfd sections is causing this issue: -------------------------------------------------------------------------------- protocol bfd { interface "o*" { interval 500 ms; idle tx interval 2 s; }; interface "i*" { interval 500 ms; idle tx interval 2 s; }; } protocol bfd { # openvpn interface "tun*" { interval 500 ms; idle tx interval 2 s; }; # transfer interface "eth0" { interval 500 ms; idle tx interval 2 s; }; } -------------------------------------------------------------------------------- Changing the bfd definition to: -------------------------------------------------------------------------------- protocol bfd { } -------------------------------------------------------------------------------- Changes the status to all sessions are up: -------------------------------------------------------------------------------- bird> show bfd sessions bfd1: IP address Interface State Since Interval Timeout 2a0a:e5c0:10:1::122 eth0 Up 12:22:52.027 0.100 0.500 2a0a:e5c0:31:12::1 oserver120 Up 12:22:52.445 0.100 0.500 2a0a:e5c0:10:1::123 eth0 Up 12:22:51.658 0.100 0.500 bird> -------------------------------------------------------------------------------- So I wonder ... is this a) a bug b) working as expected? If it is working as expected, should we add a note in the documentation saying multiple bfd instances might lead to this state / error? Best regards, Nico -- Sustainable and modern Infrastructures by ungleich.ch