When port security is disabled on a port (RHOSP17.1.4), all packets are not passed (flooded) through the tap of that port.   In some cases, operators expect a behavior similar to a promiscuous mode set on a physical interface .    There's an explicit flow that drops all traffic:

recirc_id(0),in_port(4),eth(src=20:ed:47:00:00:00,dst=60:15:2b:00:00:00),eth_type(0x8100),vlan(vid=500),encap(eth_type(0x0800),ipv4(frag=no)), packets:55202, bytes:3896218, used:1.130s, flags:SPR., actions:drop
 

which prevents the traffic from actually reaching the TAP.