Hello， Here is a description of a bug I encountered using openstack Security Group,If security groups are enabled for virtual nics on VMS, The outgoing traffic from the VMS enabled in the security group should be sent in unicast mode, but it is eventually forwarded to all ports in the vlan on the ovs br-int bridge. Does the openstack open source community have a patch to fix this bug? Can you provide patch fixed the issue? The following is my debugging process in detail. The unicast packet sent by the remote virtual machine 172.83.160.63 to the local virtual machine 172.83.160.74 is passed to the br-ex->br-int-> VM, Because the security group is enabled on the VM NIC, The br-int cannot learn the entry whose port is patch-ex and mac address is vm2. Therefore those packets sent from vm1 to vm2 are broadcast in vlans because they fail to match mac address entries. 172.83.160.74 patch-int 172.83.160.63 vm1 --- ovs(br-int) ------ ovs(br-ex)--- tor(physical switch) ......vm2 patch-ex The following is the ovs kernel flow table. The mac address of vm1 is fa:16:3e:6c:f3:09,The mac address of vm2 is fa:16:3e:d2:14:b5, the action of the flow table is multiple ports. recirc_id(0x314123),in_port(8),ct_state(-new+est-rel-rpl),eth(src=fa:16:3e:d2:14:b5,dst=fa:16:3e:6c:f3:09),eth_type(0x0800),ipv4(proto=6,frag=no),tcp(dst=2048/0xf800), packets:60100, bytes:14257193, used:2.035s, flags:P., actions:push_vlan(vid=5,pcp=0),3,pop_vlan,push_vlan(vid=1732,pcp=0),1,pop_vlan,7,9,10,15,5,18 recirc_id(0x314123),in_port(8),ct_state(-new+est-rel+rpl-inv+trk),ct_zone(0x5),ct_mark(0),eth(src=fa:16:3e:d2:14:b5,dst=fa:16:3e:6c:f3:09),eth_type(0x0800),ipv4(frag=no), packets:1, bytes:54, used:2.037s, flags:., actions:push_vlan(vid=5,pcp=0),3,pop_vlan,push_vlan(vid=1732,pcp=0),1,pop_vlan,7,9,10,15,5,18 After careful debugging analysis, the openflow action in the flow table 82 added by neutron is the VM port instead of normal. As a result, the ovs br-int bridge cannot learn the mac entry of vm2. table=82, priority=77,ct_state=+new-est,tcp,reg5=0x9,tp_dst=0x4/0xfffc actions=ct(commit,zone=NXM_NX_REG6[0..15]),output:9 table=82, priority=77,ct_state=+est-rel-rpl,tcp,reg5=0x9,tp_dst=0x4/0xfffc actions=output:9 Was the issue above fixed in the openstack ? Looking forward to reply thanks. Best Regards weichun ren