diff --git a/lib/nova b/lib/nova
index 333695e..dbfc294 100644
--- a/lib/nova
+++ b/lib/nova
@@ -213,7 +213,7 @@
             fi
         fi
 
-        if is_service_enabled quantum && [[ $Q_PLUGIN = "openvswitch" ]] && ! sudo grep -q '^cgroup_device_acl' $QEMU_CONF ; then
+        if is_service_enabled quantum && is_quantum_ovs_base_plugin "$Q_PLUGIN" && ! sudo grep -q '^cgroup_device_acl' $QEMU_CONF ; then
             # Add /dev/net/tun to cgroup_device_acls, needed for type=ethernet interfaces
             cat <<EOF | sudo tee -a $QEMU_CONF
 cgroup_device_acl = [
diff --git a/lib/quantum b/lib/quantum
index 1025d2b..0b26622 100644
--- a/lib/quantum
+++ b/lib/quantum
@@ -33,5 +33,29 @@
     sudo ovs-vsctl --no-wait br-set-external-id $bridge bridge-id $bridge
 }
 
+function quantum_setup_external_bridge() {
+    local bridge=$1
+    # Create it if it does not exist
+    sudo ovs-vsctl --no-wait -- --may-exist add-br $bridge
+    # remove internal ports
+    for PORT in `sudo ovs-vsctl --no-wait list-ports $bridge`; do
+        TYPE=$(sudo ovs-vsctl get interface $PORT type)
+        if [[ "$TYPE" == "internal" ]]; then
+            echo `sudo ip link delete $PORT` > /dev/null
+            sudo ovs-vsctl --no-wait del-port $bridge $PORT
+        fi
+    done
+    # ensure no IP is configured on the public bridge
+    sudo ip addr flush dev $bridge
+}
+
+function is_quantum_ovs_base_plugin() {
+    local plguin=$1
+    if [[ ",openvswitch,ryu," =~ ,${plugin}, ]]; then
+        return 0
+    fi
+    return 1
+}
+
 # Restore xtrace
 $XTRACE