After created two Physical Switch by Open vSwitch HWVTEP Emulator, tunnel I/F is created only in one LogicalSwitch when creating L2GW CONNECTION
By confirming with command "ovs-vsctl show", we found that the tunnel I/F was displayed only for a moment and disappeared right away. Certainly, the communication failed.

The Virtual L2 network configuration we want to create is as below:
With one L2GW node, connect one virtual LAN (vxlan) and one virtual LAN (vlan) which is on multiple (two or more) physical lines by L2

------------------(name:test-nw)
(vxlan) | |

--------------- vlan:2222(Physical line#2)

Physical configuration of L2GW Node:
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----- Physical line#1 |
----- Physical line#2

L2GW GATEWAY/CONNECTION creation command :
neutron l2-gateway-create gw1 --device name=Physical Switch(1),interface_names=Physical Port(1)
neutron l2-gateway-create gw2 --device name=Physical Switch(2),interface_names=Physical Port(2)

neutron l2-gateway-connection-create gw1 test-nw --default-segmentation-id 2222
neutron l2-gateway-connection-create gw2 test-nw --default-segmentation-id 2222

P.S

We know the following configuration can also realizes the Virtual L2 network configuration we want to create.
But Load balancing is impossible as Open vSwitch HWVTEP Emulator (ovs-vtep) process starts for each physical switch.

---------------------------------------------------

---------------------------------------------------

----- Physical line#1 |
----- Physical line#2

neutron l2-gateway-create gw1 --device name=Physical Switch(1),interface_names=Physical Port(1)
neutron l2-gateway-create gw2 --device name=Physical Switch(1),interface_names=Physical Port(2)

neutron l2-gateway-connection-create gw1 test-nw --default-segmentation-id 2222
neutron l2-gateway-connection-create gw2 test-nw --default-segmentation-id 2222