code: def notificationNch():
      
      a = L2PseudoLength(l2pLength=0x01)
      b = TpPd(pd=0x6)
      c = MessageType(mesType=0x20)  # 00100000
      d = NtNRestOctets()
      packet = a / b / c / d
      return packet
docs: NOTIFICATION/NCH Section 9.1.21b