Creates a GRE tunnel port.

        See the description of ``add_tunnel_port()``.

def add_gre_port(self, name, remote_ip,
                     local_ip=None, key=None, ofport=None):
        """
        Creates a GRE tunnel port.

        See the description of ``add_tunnel_port()``.
        """
        self.add_tunnel_port(name, 'gre', remote_ip,
                             local_ip=local_ip, key=key, ofport=ofport)