1. ovs connect to odl using below command
sudo ovs-vsctl set-manager tcp:10.43.174.155:6640
2. creat network, subnet, and vm on openstack.
the port and flows added to ovs please see the attachment
3. make the ovs reconnect to odl using follow commands
sudo ovs-vsctl set-manager tcp:127.0.0.1:6640
sudo ovs-vsctl set-manager tcp:10.43.174.155:6640
here, the datapath id will changed to a new one
4. creat new vm on the network, and then, the flows is not correct.
the reason is that: new port added to ovs causing new flow added
the added flow will be base on the new datapath id, the old flow on ovs would be overwrite