def _get_port_to_string(iface):
    """Simple helper which allows to get string representation for interface.

    Args:
        iface(list): Which IXIA interface to use for packet sending (list in format [chassis_id, card_id, port_id])

    Returns:
        str: string in format "chassis_id/card_id/port_id"

    """
    return "/".join(map(str, iface))