In Compute and Network Node

**$ sudo ovs-ofctl show br-tun

OFPT_FEATURES_REPLY (xid=0x2): dpid:0000a2d42c663046 n_tables:254, n_buffers:256 capabilities: FLOW_STATS TABLE_STATS PORT_STATS QUEUE_STATS ARP_MATCH_IP actions: OUTPUT SET_VLAN_VID SET_VLAN_PCP STRIP_VLAN SET_DL_SRC SET_DL_DST SET_NW_SRC SET_NW_DST SET_NW_TOS SET_TP_SRC SET_TP_DST ENQUEUE 1(patch-int): addr:2e:14:d5:90:e7:4d config: 0 state: 0 speed: 0 Mbps now, 0 Mbps max LOCAL(br-tun): addr:a2:d4:2c:66:30:46 config: 0 state: 0 speed: 0 Mbps now, 0 Mbps max OFPT_GET_CONFIG_REPLY (xid=0x4): frags=normal miss_send_len=0**

So, gre module disapper. I don't know Why. I checked th log that found the ERROR as follow:

ERROR neutron.agent.linux.ovs_lib [-] Unable to execute ['ovs-vsctl', '--timeout=2', 'list-ports', 'br-int']. Exception:Command: ['sudo', '/usr/bin/neutron-rootwrap', '/etc/neutron/rootwrap.conf', 'ovs-vsctl','--timeout=2', 'list-ports','br-int'] Exit code: 1 stdout: '' stderr: '2013-12-27T04:38:11Z|00001|reconnect|WARN|unix:/var/run/openvswitch/db.sock:connection attempt failed(No such file or directory)\novs-vsctl: unix:/var/run/openvswitch/db.sock: databaseconnection failed(No such file or directory)\n'