What is the MOST optical bus in the Mercedes E-Class (W211)

The MOST optical bus at Mercedes E-Class (W211) replaced D2B in older models. Although they are not interchangeable, they are characterized by the same working principle. All the peripheral devices in the car are combined with one optical ring if the ring stops, it leads to total inoperability. If the vehicle has an integrated amplifier, there is no optical ring to operate on the radio and read the drives.