Method for operating an ethernet on-board electrical system of a motor vehicle, control unit and ethernet on-board electrical system

1. A method for operating an Ethernet on-board electrical system of a motor vehicle, the method comprising:

determining a connection delay of a first signal on a first connection path between a first control unit of the Ethernet on-board electrical system and a second control unit of the Ethernet on-board electrical system;

determining a maximum speed of the first connection path based on the connection delay; and

determining a type or physical medium of a transmission medium of the first connection path based on the connection delay and the maximum speed.

2. The method according to claim 1 , which further comprises communicating a type of the transmission medium to a program in the Ethernet onboard electrical system and adapting a connection path selection of the program based on the transmission medium.

3. The method according to claim 1 , which further comprises providing a transmission reliability value describing a loss probability of data transmitted via the first connection path, and assigning the transmission reliability value to the first connection path based on the transmission medium.

4. The method according to claim 1 , which further comprises determining delays of a plurality of signals on the first connection path, selecting a shortest delay of the plurality of signals, and determining the maximum speed of the first connection path based on the shortest delay.

5. The method according to claim 1 , which further comprises:

providing a second connection path between the first control unit and the second control unit, the second connection path being different from the first connection path;

determining a delay of a second signal on the second connection path;

determining a maximum speed of the second connection path; and

determining a transmission medium of the second connection path based on the delay and the maximum speed of the second connection path.

6. The method according to claim 5 , which further comprises:

providing a third control unit of the Ethernet on-board electrical system;

providing a third connection path connected indirectly to the first control unit and connected between the second control unit and the third control unit;

determining a connection delay of the first signal by using the first control unit and determining a delay of a third signal on the third connection path by using the third control unit; and

triggering the determination of the connection delay of the third signal by using a service message transmitted from the first control unit to the third control unit.

7. The method according to claim 1 , which further comprises carrying out the method after at least one of a change of the first control unit from a normal operating mode into an energy-saving mode or a change from the energy-saving mode into the normal operating mode.

8. A method for operating an Ethernet on-board electrical system of a motor vehicle, the method comprising:

determining a connection delay of a first signal on a first connection path between a first control unit of the Ethernet on-board electrical system and a second control unit of the Ethernet on-board electrical system;

determining a maximum speed of the first connection path based on the connection delay; and

determining a type or physical medium of a transmission medium of the first connection path based on the connection delay and the maximum speed, wherein the determined type or physical medium of the transmission medium is selected from the group consisting of optical, copper or wireless.

9. A control unit for an Ethernet on-board electrical system, the control unit comprising a first control unit configured:

to transmit a signal to a second control unit of the Ethernet on-board electrical system and to receive the signal from the second control unit;

to determine a connection delay of the signal on a connection path to the second control unit;

to determine a maximum speed of the connection path based on the connection delay; and

to determine a type or physical medium of a transmission medium of the connection path based on the connection delay and the maximum speed.

10. An Ethernet on-board electrical system for a motor vehicle, the Ethernet on-board electrical system comprising:

a first control unit configured:

to transmit a signal to a second control unit of the Ethernet on-board electrical system and to receive the signal from the second control unit:

to determine a connection delay of the signal on a connection path to the second control unit;

to determine a maximum speed of the connection path based on the connection delay; and

to determine a type or physical medium of a transmission medium of the connection path based on the connection delay and the maximum speed;

a second control unit; and

at least one connection path interconnecting the first and second control units.

11. The Ethernet on-board electrical system according to claim 10 , which further comprises:

a third control unit of the Ethernet on-board electrical system, the third control unit being indirectly connected to the first control unit;

a third connection path directly connecting the third control unit to the second control unit;

the third control unit configured to determine a delay of a third signal on the third connection path; and

the first control unit configured to trigger the determination of the connection delay of the third signal by using a service message sent to the third control unit.