'Creates one network with one segment and one subnet'

def _create_test_segment_with_subnet(self, network=None, cidr='2001:db8:0:0::/64', physnet='physnet'):

    (network, segment) = self._create_test_network_and_segment(network, physnet)
    subnet = self._create_test_subnet_with_segment(network, segment, cidr)
    return (network, segment, subnet)
