+ int (*set_config)(struct netdev_dev *netdev_dev, const struct smap *args);
+
+ /* Returns the tunnel configuration of 'netdev_dev'. If 'netdev_dev' is
+ * not a tunnel, returns null.
+ *
+ * If this function would always return null, it may be null instead. */
+ const struct netdev_tunnel_config *
+ (*get_tunnel_config)(const struct netdev_dev *netdev_dev);