Hello! I run two Centos 7 servers. They are connected over ipsec+gre, both run bird 2.0.5 ospf. I also have bfd enabled: bfd yes; in this interface and protocol bfd { interface "gre*" { interval 200 ms; }; }; Both sides had following messages in logs: Sep 12 08:18:23 ast-p245a bird: bfd1: Bad packet from 192.168.201.85 - unknown session id (1935426703) Sep 12 08:18:45 ast-ngdu2 bird: bfd1: Bad packet from 192.168.201.86 - unknown session id (913048279) And I had ospf error messages: Sep 8 03:31:04 ast-p245a bird: MyOSPF: Authentication failed for nbr 192.168.46.74 on gre2 - lower sequence number (rcv 1565416592, old 1566997226) Sep 8 03:31:04 ast-p245a bird: MyOSPF: Authentication failed for nbr 192.168.46.74 on gre2 - lower sequence number (rcv 1565416592, old 1566997226) Sep 8 03:31:04 ast-ngdu2 bird: MyOSPF: Authentication failed for nbr 192.168.26.2 on gre2 - lower sequence number (rcv 1565670907, old 1567089417) Sep 8 03:31:04 ast-ngdu2 bird: MyOSPF: Authentication failed for nbr 192.168.26.2 on gre2 - lower sequence number (rcv 1565670907, old 1567089417) One of servers got NetworkManager problem as result today Sep 8 03:31:21 ast-p245a NetworkManager[987]: <info> [1567899081.4736] platform-linux: netlink: read: too many netlink events. Need to resynchronize plat form cache There are many such messages in log And had connectivity problem, so I rebooted it and disabled bfd on both sides. Problem disappeared. May be there were problem on link, but I have two another servers on this link with identical config, but they run quagga. Don't sure this is bird problem, but may be somebody had the same problem before? Thank you!