Comment 32 for bug 1837252

its not that ageing prevents the vm receiving the packet.
it worked without ageing because the unicast packets were bing flooded

so that is why it "works" with ageing disabled. based on our irc conversation i think
the flooding was masking a different proablem in the linux bridge agent where it was/is
incorrectly setting entries in the bridge fdb against the vlan interface instead of the tap