Hi,All. Recently I deploy an Openstack(Mitaka)+OVS(use VLAN isolation) in my lab,but I meet some problem. Here is my package version: [root@my1n12nt ~]# uname -r 3.10.0-514.26.2.el7.x86_64 [root@my1n12nt ~]# cat /etc/redhat-release CentOS Linux release 7.3.1611 (Core) [root@my1n12nt ~]# rpm -qa |grep openvswitch openvswitch-2.6.1-4.1.git20161206.el7.x86_64 python-openvswitch-2.6.1-4.1.git20161206.el7.noarch openstack-neutron-openvswitch-8.4.0-1.el7.noarch [root@my1n12nt ~]# rpm -qa |grep openstack openstack-neutron-common-8.4.0-1.el7.noarch openstack-neutron-ml2-8.4.0-1.el7.noarch openstack-neutron-8.4.0-1.el7.noarch openstack-neutron-openvswitch-8.4.0-1.el7.noarch openstack-neutron-fwaas-8.4.0-1.el7.noarch When installed finish the Openstack is fine.Sometime the OVS will going fail. Partial log file from ovs-vswitched.log: 2250 2017-10-16T09:19:00.318Z|12163|bridge|INFO|bridge br-int: added interface tap1839b0de-48 on port 1056 2251 2017-10-16T09:19:00.622Z|12164|netdev_linux|INFO|ioctl(SIOCGIFHWADDR) on tap1839b0de-48 device failed: No such device 2252 2017-10-16T09:19:01.738Z|12165|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2253 2017-10-16T09:19:01.753Z|12166|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2254 2017-10-16T09:19:01.769Z|12167|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2255 2017-10-16T09:19:01.784Z|12168|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2256 2017-10-16T09:19:01.797Z|12169|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2257 2017-10-16T09:19:02.662Z|12170|bridge|INFO|bridge br-int: added interface tap95a163a1-f7 on port 1057 2258 2017-10-16T09:19:02.965Z|12171|netdev_linux|INFO|ioctl(SIOCGIFHWADDR) on tap95a163a1-f7 device failed: No such device 2259 2017-10-16T09:19:04.317Z|12172|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2260 2017-10-16T09:19:04.330Z|12173|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2261 2017-10-16T09:19:04.345Z|12174|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2262 2017-10-16T09:19:04.359Z|12175|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2263 2017-10-16T09:19:04.375Z|12176|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2264 2017-10-16T09:19:05.285Z|12177|bridge|INFO|bridge br-int: added interface tap413a5f1b-79 on port 1058 2265 2017-10-16T09:19:05.601Z|12178|netdev_linux|INFO|ioctl(SIOCGIFHWADDR) on tap413a5f1b-79 device failed: No such device 2266 2017-10-16T09:19:05.605Z|12179|netdev_linux|WARN|Dropped 9 log messages in last 12 seconds (most recently, 2 seconds ago) due to excessive rate 2267 2017-10-16T09:19:05.605Z|12180|netdev_linux|WARN|ioctl(SIOCGIFINDEX) on tap413a5f1b-79 device failed: No such device 2268 2017-10-16T09:19:07.817Z|12181|netlink_socket|ERR|fcntl: Too many open files 2269 2017-10-16T09:19:07.817Z|12182|dpif|WARN|system@ovs-system: failed to add tap50aa4927-e8 as port: Too many open files 2270 2017-10-16T09:19:07.919Z|12183|netlink_socket|ERR|fcntl: Too many open files 2271 2017-10-16T09:19:07.919Z|12184|dpif|WARN|system@ovs-system: failed to add tap50aa4927-e8 as port: Too many open files 2272 2017-10-16T09:19:08.055Z|12185|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2273 2017-10-16T09:19:08.070Z|12186|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2274 2017-10-16T09:19:08.085Z|12187|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2275 2017-10-16T09:19:08.098Z|12188|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2276 2017-10-16T09:19:08.112Z|12189|connmgr|INFO|br-int<->unix: 1 flow_mods in the last 0 s (1 deletes) 2277 2017-10-16T09:19:08.153Z|12190|netlink_socket|ERR|fcntl: Too many open files 2278 2017-10-16T09:19:08.154Z|12191|dpif|WARN|system@ovs-system: failed to add tap50aa4927-e8 as port: Too many open files 2279 2017-10-16T09:19:08.989Z|12192|netlink_socket|ERR|fcntl: Too many open files 2280 2017-10-16T09:19:08.989Z|12193|dpif|WARN|system@ovs-system: failed to add tap64de99f1-2d as port: Too many open files More info see my attachment. Hope this helps some, Thanks.