OSI Layers in Automotive Networks - IEEE...

OSI Layers in Automotive Networks

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OSI Layers in Automotive Networks 2013-03-20

IEEE 802.1 Plenary Meeting - Orlando

Aboubacar Diarra, Robert Bosch GmbH

2013-03-20 - IEEE 802.1 Plenary Meeting - Orlando


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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



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OSI Reference Model

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

Application A

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data Link

1 Physical

Application B

Transmission Medium

Data

Application Protocol

Communication Protocol

Bit Transmission Protocol

3 relevant Layers for

Automotive Control Data

Communication with Area

Busses: Layers 1, 2 and 7

ECU 1 ECU 2



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Simplified generic Architecture for Automotive

Serial Busses

Bus Node

Communication

Application

Communication

Controller

Transceiver

Bus Node

Communication

Application

Communication

Controller

Transceiver

Communication Protocol

Physical Layer Definition

BUS

Layer 7

Layer 1, 2

Layer 1


Layer 1, 2, 4*


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Basic Automotive E/E Architecture

Central

Gateway

LIN High

speed

CAN

FlexRay CAN

MOST

Layer 1 to 7

Layer 4 *

Diagnosis

over CAN

* Layer 4 is used in this case for Diagnosis Services

Layer 1, 2, 4* Layer 1, 2, 4*



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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



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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



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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


Layer 2


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Ethernet Impact on Automotive Bus Layering:

Example of On-Board Communication *

Central

Gateway

LIN High

speed

CAN

FlexRay CAN

Switch

Ethernet

Remark:

Layer 3 and 4 can be

solicited for Car2X

Communication

Applications.

* Excepted On-Board Diagnosis (OBD)

which needs a Layer 4 support



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Ethernet Impact on Automotive Bus Layering:

Example of Off-Board Communication

Central

Gateway

LIN High

speed

CAN

FlexRay CAN

Layer 4

Layer 3 / 4 Diagnosis

over IP (DoIP)

Switch

Ethernet

Layer 3 / 4



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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



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Conclusion(2)

Therefore, for a Control Data Communication that occurs in an In-

vehicle 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



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Thank You for your Attention


OSI Layers in Automotive Networks - IEEE...

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