Good day, There seems to be a multicast related bug with FreeBSD 11.1 and Bird 1.6.3. In summary: Two problems: * Ethernet interfaces configured as "broadcast" do not emit any OSPF packets, as observed by tcpdump. * Above interfaces receive OSPF packets from Linux neighbours (as seen by tcpdump), but Bird does not receive them (nothing logged in debug mode). Two workarounds: * Enabling "real broadcast" solves both problems above, but it must be enabled on all peers' configs so that everyone broadcasts. * Configuring interfaces as nbma on all peers also solves both problems. While Bird is running, there seem to be no OSPF multicast memberships reported by ifmcstat(8), eg. # ifmcstat -i vtnet1 -v vtnet1: inet 192.168.102.16 igmpv3 rv 2 qi 125 qri 10 uri 3 group 224.0.0.1 mode exclude mcast-macaddr 01:00:5e:00:00:01 link 52:54:00:85:d7:51 group 01:00:5e:00:00:01 I have also tried disabling firewalls, and have not seen any "Permission denied" socket errors logged by Bird in debug mode. I'd be delighted to help test/find a fix with my lab setup, but for now I'm a bit lost for digging into code and kernel APIs, which is where I suspect the problem lies. Any ideas where to start? Thanks, Aragon