def normalize_lun(scsi_id):
    """Normalize the lun id to Big Endian

    :param scsi_id: Volume lun id
    :return: Converted LUN id in Big Endian as per the RFC 4455
    """
    lun = '%x' % int(scsi_id)
    if len(lun) == 8:
        lun += '00000000'
    else:
        lun += '000000000000'
    return lun
