On two servers (different hardware) created vlans 217-227 on Ethernet interfaces.
Servers connect via switch.
Vlans added in bridge.
On the bridge created carp option.
Client PC connected to servers in vlan 217.
Carp works fine. 
When client generate some traffic (something like ping) to Server the
system hung without any log messages.

How-To-Repeat: In server 1 setings /etc/rc.conf:
cloned_interfaces="vlan217 \
vlan218 \
vlan219 \
vlan220 \
vlan221 \
vlan222 \
vlan223 \
vlan224 \
vlan225 \
vlan226 \
vlan227 \
vlan500 \
bridge0"
internal_if="em0"
ifconfig_vlan217="vlan 217 vlandev ${internal_if}"
ifconfig_vlan218="vlan 218 vlandev ${internal_if}"
ifconfig_vlan219="vlan 219 vlandev ${internal_if}"
ifconfig_vlan220="vlan 220 vlandev ${internal_if}"
ifconfig_vlan221="vlan 221 vlandev ${internal_if}"
ifconfig_vlan222="vlan 222 vlandev ${internal_if}"
ifconfig_vlan223="vlan 223 vlandev ${internal_if}"
ifconfig_vlan224="vlan 224 vlandev ${internal_if}"
ifconfig_vlan225="vlan 225 vlandev ${internal_if}"
ifconfig_vlan226="vlan 226 vlandev ${internal_if}"
ifconfig_vlan227="vlan 227 vlandev ${internal_if}"
ifconfig_bridge0="inet 10.100.15.250 netmask 255.255.240.0 \
         addm vlan217 \
         addm vlan218 \
         addm vlan219 \
         addm vlan220 \
         addm vlan221 \
         addm vlan222 \
         addm vlan223 \
         addm vlan224 \
         addm vlan225 \
         addm vlan226 \
         addm vlan227 "
ifconfig_bridge0_alias0="inet vhid 202 pass password advbase 4 advskew 90 10.100.15.254/32 add"

In server 2 setings /etc/rc.conf:
cloned_interfaces="vlan217 \
vlan218 \
vlan219 \
vlan220 \
vlan221 \
vlan222 \
vlan223 \
vlan224 \
vlan225 \
vlan226 \
vlan227 \
vlan500 \
bridge0"
internal_if="igb1"
ifconfig_vlan217="vlan 217 vlandev ${internal_if}"
ifconfig_vlan218="vlan 218 vlandev ${internal_if}"
ifconfig_vlan219="vlan 219 vlandev ${internal_if}"
ifconfig_vlan220="vlan 220 vlandev ${internal_if}"
ifconfig_vlan221="vlan 221 vlandev ${internal_if}"
ifconfig_vlan222="vlan 222 vlandev ${internal_if}"
ifconfig_vlan223="vlan 223 vlandev ${internal_if}"
ifconfig_vlan224="vlan 224 vlandev ${internal_if}"
ifconfig_vlan225="vlan 225 vlandev ${internal_if}"
ifconfig_vlan226="vlan 226 vlandev ${internal_if}"
ifconfig_vlan227="vlan 227 vlandev ${internal_if}"
ifconfig_bridge0="inet 10.100.15.251 netmask 255.255.240.0 \
         addm vlan217 \
         addm vlan218 \
         addm vlan219 \
         addm vlan220 \
         addm vlan221 \
         addm vlan222 \
         addm vlan223 \
         addm vlan224 \
         addm vlan225 \
         addm vlan226 \
         addm vlan227 "
ifconfig_bridge0_alias0="inet vhid 202 pass password advbase 2 advskew 50 10.100.15.254/32 add"

In client PC setings:
IP: 10.100.0.100
Netmask: 255.255.240.0
Generate some traffic several minutes:
ping 10.100.15.254