OK, A few more tests done. It seems it is the multicast being blocked. If I use carppeer then it starts to work and I can see packets on the vlan interface with tcpdump.
So here is my ifconfig setup: # ifconfig -a lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33152 priority: 0 groups: lo inet6 ::1 prefixlen 128 inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2 inet 127.0.0.1 netmask 0xff000000 enc0: flags=0<> priority: 0 groups: enc status: active bnx0: flags=8b43<UP,BROADCAST,RUNNING,PROMISC,ALLMULTI,SIMPLEX,MULTICAST> mtu 1500 lladdr 00:10:18:d2:d3:ec priority: 0 media: Ethernet autoselect (1000baseT full-duplex) status: active inet6 fe80::210:18ff:fed2:d3ec%bnx0 prefixlen 64 scopeid 0x3 bnx1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 lladdr 00:10:18:d2:d3:ee priority: 0 media: Ethernet autoselect (1000baseT full-duplex) status: active inet6 fe80::210:18ff:fed2:d3ee%bnx1 prefixlen 64 scopeid 0x4 bnx2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 lladdr d0:67:e5:f4:0f:40 priority: 0 media: Ethernet autoselect (1000baseT full-duplex) status: active inet6 fe80::d267:e5ff:fef4:f40%bnx2 prefixlen 64 scopeid 0x5 bnx3: flags=8802<BROADCAST,SIMPLEX,MULTICAST> mtu 1500 lladdr d0:67:e5:f4:0f:41 priority: 0 media: Ethernet autoselect (none) status: no carrier vlan1: flags=0<> mtu 1500 lladdr 00:00:00:00:00:00 priority: 0 groups: vlan vlan101: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 lladdr d0:67:e5:f4:0f:40 description: Netsight office priority: 0 vlan: 101 priority: 0 parent interface: bnx2 groups: vlan egress status: active inet6 fe80::d267:e5ff:fef4:f40%vlan101 prefixlen 64 scopeid 0x8 inet 192.168.87.22 netmask 0xffffff00 broadcast 192.168.87.255 vlan119: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500 lladdr 00:10:18:d2:d3:ec description: Scottles Server priority: 0 vlan: 119 priority: 0 parent interface: bnx0 groups: vlan status: active inet6 fe80::210:18ff:fed2:d3ec%vlan119 prefixlen 64 scopeid 0xa inet 213.133.66.65 netmask 0xfffffff8 broadcast 213.133.66.71 pflog0: flags=141<UP,RUNNING,PROMISC> mtu 33152 priority: 0 groups: pflog carp119: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 lladdr 00:00:5e:00:01:77 priority: 0 carp: MASTER carpdev vlan119 vhid 119 advbase 1 advskew 10 groups: carp status: master inet 213.133.66.67 netmask 0xfffffff8 broadcast 213.133.66.71 inet6 fe80::200:5eff:fe00:177%carp119 prefixlen 64 scopeid 0xc If I try a tcpdump with the above (multicast carp) I get nothing yet if I set the carppeer it then works: # ifconfig carp119 carppeer 213.133.66.66 # tcpdump -v -ni vlan119 tcpdump: listening on vlan119, link-type EN10MB tcpdump: WARNING: compensating for unaligned libpcap packets 15:10:37.504188 carp 213.133.66.65 > 213.133.66.66: CARPv2-advertise 36: vhid=119 advbase=1 advskew=10 demote=0 (DF) [tos 0x10] (ttl 255, id 55125, len 56) 15:10:38.554236 carp 213.133.66.65 > 213.133.66.66: CARPv2-advertise 36: vhid=119 advbase=1 advskew=10 demote=0 (DF) [tos 0x10] (ttl 255, id 23222, len 56) 15:10:39.604283 carp 213.133.66.65 > 213.133.66.66: CARPv2-advertise 36: vhid=119 advbase=1 advskew=10 demote=0 (DF) [tos 0x10] (ttl 255, id 45911, len 56) 15:10:40.654331 carp 213.133.66.65 > 213.133.66.66: CARPv2-advertise 36: vhid=119 advbase=1 advskew=10 demote=0 (DF) [tos 0x10] (ttl 255, id 38039, len 56) 15:10:41.704379 carp 213.133.66.65 > 213.133.66.66: CARPv2-advertise 36: vhid=119 advbase=1 advskew=10 demote=0 (DF) [tos 0x10] (ttl 255, id 59255, len 56) ^C 6 packets received by filter 0 packets dropped by kernel If I set the carppeer back to being multicast then it stops working: # ifconfig carp119 carppeer 224.0.0.18 # tcpdump -v -ni vlan119 tcpdump: listening on vlan119, link-type EN10MB ^C 0 packets received by filter 0 packets dropped by kernel So it appears there is somewhere a problem with multicast packets being filtered out somewhere. This is all running with pfctl -d -Matt