I don't use VLAN. It's just a simple and unique bridge(4). The tap is added, so are the second ix0 interface (local network), re0 and the spaned em0. The internal settings have a little evolued since this last schema (re0 is now used to communicate with SELKS and SELKS is hosted on a NUC).The "virtual bridge" in your setup, is that just a bridge interface on the FreeBSD host? In this bridge, your tap interface of the Opensense VM is added? How is the throughput? Do you have multiple VLAN's? (so multiple bridges?)