OSI Layers in Automotive Networks

Transcription

1 OSI Layers in Automotive Networks IEEE Plenary Meeting - Orlando Aboubacar Diarra, Robert Bosch GmbH 1

2 Outline OSI Reference Model Simplified generic Architecture for Automotive Serial Busses Basic Automotive E/E Architecture Automotive Bus Systems in the OSI Model Ethernet Impact on Automotive Bus Layering 2

3 OSI Reference Model ECU 1 ECU 2 Data Application A Application B 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Application Protocol 3 relevant Layers for Automotive Control Data Communication with Area Busses: Layers 1, 2 and 7 Communication Protocol Bit Transmission Protocol 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Transmission Medium 3

4 Simplified generic Architecture for Automotive Serial Busses Bus Node Bus Node Application Application Layer 7 Communication Communication Communication Controller Communication Protocol Communication Controller Layer 1, 2 Transceiver Physical Layer Definition Transceiver Layer 1 BUS 4

5 Basic Automotive E/E Architecture Layer 4 * Central Gateway Diagnosis over CAN CAN FlexRay LIN High speed CAN MOST Layer 1, 2, 4* Layer 1, 2, 4* Layer 1, 2, 4* Layer 1 to 7 * Layer 4 is used in this case for Diagnosis Services 5

6 Automotive Bus Systems in the OSI Model: Example of the CAN Bus 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Logical Link Control (LLC) Acceptance Filtering Overload Notification Recovery Management Medium Access control(mac) Data Encapsulation/Decapsulation Frame Coding Error Detection/Signaling/Handling Physical Signaling (PLS) Bit Encoding/Decoding Bit Time Synchronization Physical Medium attachment(pma) Driver/Receiver Characteristics Media Dependant Interface(MDI) Connectors 6

7 Automotive Bus Systems in the OSI Model: Example of the FlexRay Bus 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Logical Link Control (LLC) Protocol Operation Control Medium Access control(mac) Message Framing Communication Cycle Physical Signaling (PLS) Bit Encoding/Decoding Bit Time Synchronization Physical Medium attachment(pma) Driver/Receiver Characteristics Media Dependant Interface(MDI) Connectors 7

8 Automotive Bus Systems in the OSI Model: Example of the MOST Bus 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Application Programming Interface Netservices Layer 2 Netservices Layer 1 MOST Transceiver Electrical PHY, FOT s Connectors and Plastic Fiber 8

9 Ethernet Impact on Automotive Bus Layering: Example of On-Board Communication * Central Gateway Remark: Layer 3 and 4 can be solicited for Car2X Communication Applications. Switch CAN FlexRay LIN * Excepted On-Board Diagnosis (OBD) which needs a Layer 4 support Layer 2 High speed CAN Ethernet 9

10 Ethernet Impact on Automotive Bus Layering: Example of Off-Board Communication Layer 3 / 4 Central Gateway Diagnosis over IP (DoIP) Switch CAN FlexRay LIN Layer 4 High speed CAN Ethernet Layer 3 / 4 10

11 Conclusion(1) In reference to the OSI Data Communication Model, the Serial Interface of CAN, FlexRay and LIN Busses typically needs 3 OSI Layers for On- Board Communication excepted OBD: the Physical Layer, the Data Link Layer and the Application Layer The MOST Bus covers all the 7 OSI Layers for On-Board Communication The Transport Layer is used for Off-Board Communication like Diagnosis and also for OBD on these typical Automotive Area Networks. The Layers 3 and 4 can be used for Vehicle On-Board Communication in Car2X Communication Applications 11

12 Conclusion(2) Therefore, for a Control Data Communication that occurs in an Invehicle closed Network, the need of the Layer 2 is justified. On top of that, Layer 3 Routing Processes require more infrastructure (eg. IP stack implementation, software implementation, memory need...) and costs investments than Layer 2 solutions from an Automotive Perspective For In-vehicle Control Applications which require a very low Latency, a Layer 2 solution is more pragmatic than a Layer 3 solution However, Diagnosis over IP, Car2X and In-Car Wireless Communication Applications need Layer 3 Routing Support 12

13 Thank You for your Attention 13