Comment 6 for bug 2048785

I had some time to look into what are the minimal necessary conditions for the bugs reproduced in comment #2.

The forwarding problem is present in all ml2/ovs environments where a trunk port is set up by the ovs-agent and when the trunk bridge is flooding traffic. The values of firewall_driver and explicitly_egress_direct are irrelevant.

The flooding problem requires more. It is only present if explicitly_egress_direct is set to True (that's when the forwarding is asymmetric - direct output action in egress direction, but normal action in ingress direction). I did not open a new bug report yet, because I believe this problem was already reported here: https://bugs.launchpad.net/neutron/+bug/1884708 This bug report seems to be fixed by https://review.opendev.org/c/openstack/neutron/+/738551. However I believe that change did not fix all cases of the bug. It fixed the flooding problem with firewall_driver=noop. However it did not fix it with firewall_driver=openvswitch. I did not test with other firewall_drivers yet. I think we should reopen #1884708.