The following procedure is tested on OpenStack grizzly version running on Ubuntu 12.04
Before creation of any networks in the OpenStack setup, add the following lines in /etc/quantum/plugins/openvswitch/ovs_quantum_plugin.ini under “[OVS]” section on all the machines of an OpenStack setup running Open vSwitch and Open vSwitch agents.
tenant_network_type = gre tunnel_id_ranges = 1:1000 enable_tunneling = True local_ip = 192.168.100.1 tunnel_bridge = br-tun
Create and configure bridges on all machines running Quantum and OpenvSwitch components
ovs-vsctl add-br br-int
Restart appropriate services
/etc/init.d/openvswitch-switch restart /etc/init.d/quantum-plugin-openvswitch-agent restart
If Quantum server is running in the machine. Restart it.
/etc/init.d/quantum-server restart
Now create networks as per the requirement, using Nova commands or the OpenStack Dashboard.