Tunnel I/F is not created in L2GW(OVS HWVTEP Emulator) LogicalSwitch sometimes when network / subnet / GATEWAY / CONNECTION are created continuously by CLI with shell script.
By confirmed several times, we found that the probability of successful tunnel I/F creation will increase if sleep time is added.
Below are results after adding sleep time in each step respectively.
 * Results of set sleep time in different steps (5 loops executed for each pattern)
    pattern                       OK          NG
  --------------------------------------------------
  no sleep                        0             5
  sleep set point(*1)        2             3
  sleep set point(*2)        0             5
  sleep set point(*3)        0             5
  sleep set point(*4)        0             5
  sleep set point(*5)        2             3(*tunnel I/F created but ping failed)
  sleep set point(*6)        0             5
  sleep set point(*7)        0             5
  --OK: Tunnel I/F created, Ping also OK
  --NG: Tunnel I/F not created, Ping failed

○Reproduction steps:
1. OpenDaylight / Open vSwitch Initialization (no entry in openstack)
    Controller node Open vSwitch start and initial setting
    * sleep set point(*1) 5s
2. L2GW node Open vSwitch start
    * sleep set point(*2) 5s
3. L2GW node Open vSwitch initial setting (Non-HA)
    * sleep set point(*3) 5s
4. Network / Subnet / L2 GATEWAY / L2 CONNECTION creation
    openstack network create test-nw
    * sleep set point(*4) 5s
    openstack subnet create --network test-nw --dhcp --subnet-range 192.168.0.0/24 test-subnw
    * sleep set point(*5) 5s
    neutron l2-gateway-create gw --device name=ocata-l2gw1,interface_names=patch-vlan
    * sleep set point(*5) 5s
    neutron l2-gateway-connection-create gw test-nw --default-segmentation-id 1111
5. Ping confirmation
    * sleep set point(*7) 5s
    from: DHCP namespace, to: dummy port
6. Log and detail info collection
    ovs-vsctl show
    ovsdb-client dump hardware_vtep
    /opt/karaf-0.7.1/data/log/karaf.log
    curl -s -u admin:admin http://127.0.0.1:8080/restconf/config/network-topology:network-topology | python -mjson.tool