if_bridge stops when running virtualbox 4.1.8

[Paul Schenkeveld]

Hi,

I just noticed that when running Virtualbox 4.1.8 with a bridged network
interface, I loose connectivity to another virtual host running in qemu
whose network interface is bridged to my ethernet interface.  After
stopping the Virtualbox instance, I regain connection to the virtual
host under qemu.  Ifconfig doesn't give a clue.  Has anyone seen this
behaviour or, even better, have a solution?

My host is running 8.2-RELEASE, here's the relevant ifconfig output:

em0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu
+1500
        options=2098<VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC>
        ether 00:1f:16:xx:xx:xx
        inet 10.0.0.10 netmask 0xffffff00 broadcast 10.0.0.255
        nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
tap0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu
+1500
        options=80000<LINKSTATE>
        ether 00:bd:32:xx:xx:xx
        nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
        Opened by PID 13433
bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 8a:55:3f:xx:xx:xx
        id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
        maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
        root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
        member: tap0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
                ifmaxaddr 0 port 5 priority 128 path cost 2000000
        member: em0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
                ifmaxaddr 0 port 1 priority 128 path cost 20000
vboxnet0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 0a:00:27:00:00:00

Thanks!

Paul Schenkeveld