FreeBSD 11.1 OSPF multicast broken?

[Aragon Gouveia]

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