An Extension of the OMNeT++ INET Framework for Simulating ... - CoRE

An Extension of the OMNeT++ INET Framework for Simulating Real-time Ethernet with High Accuracy 4th international OMNeT++ Workshop Till Steinbach, Hermand Dieumo Kenfack, Franz Korf, Thomas C. Schmidt {till.steinbach,hermand.dieumo,korf,schmidt} @informatik.haw-hamburg.de Hamburg University of Applied Sciences

Barcelona, Spain, March, 21st 2011

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Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences

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Agenda

Simulating Real-time Ethernet

1 Introduction

Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt Introduction

2 Background

Background Concept & Model

3 Concept & Model

Results & Evaluation Conclusion & Outlook

4 Results & Evaluation 5 Conclusion & Outlook


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Motivation Why a new in-vehicle communication technology?

RE Simulating Real-time Ethernet Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt Introduction Background Concept & Model Results & Evaluation Conclusion & Outlook


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Motivation Why a new in-vehicle communication technology?

RE Simulating Real-time Ethernet Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt

“Actually already today the electrical system in the whole car is not adequately controllable” and “The complexity continues to increase” 1 Richard Bogenberger (2008) BMW Group Research and Technology

1

Introduction Background Concept & Model Results & Evaluation Conclusion & Outlook

Jens Badstübner: “Kollaps im Bordnetz: Schluss mit Can, Lin und Flexray”. 2008.


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Motivation Why Ethernet?


Mature technology

Introduction Background

High transmission bandwidth

Concept & Model

Low prices for Ethernet components

Results & Evaluation

Many development/diagnostic tools and expert developers

Conclusion & Outlook


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RE

Agenda


1 Introduction


2 Background


3 Concept & Model




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Real-time Ethernet Real-time extensions for standard switched Ethernet

RE Simulating Real-time Ethernet

Standard switched Ethernet has no real-time capabilities There are extensions of various operational areas Extensions can be classified in: token-based technologies e.g. EtherCAT 2 bandwidth-limiting technologies e.g. Avionics Full DupleX Switched Ethernet (AFDX) 3 time-triggered technologies e.g. Profinet, SynqNet, RTnet, POWERLINK, TTEthernet 1

Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt Introduction Background Concept & Model Results & Evaluation Conclusion & Outlook


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TTEthernet A time-triggered real-time Ethernet protocol


Basis by the Technical University Vienna (2004) Today development by TTTech Computertechnik Currently standardization by the Society of Automotive Engineers

Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt Introduction Background Concept & Model

3 traffic classes: Time-triggered (TT) highest priority, time-triggered, cyclic, offline planned, requires synchronised time Rate-constrained (RC) event-triggered, bandwidth-based (AFDX) Best-effort (BE) lowest priority, standard Ethernet



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TTEthernet Synchronisation


End System Sync Client

Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt Introduction Background

1. PCF (time) End System Sync Master

Switch Compression Master

Concept & Model



1. PCF (time)

End System Sync Master


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TTEthernet Synchronisation



Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt

2. PCF (new Time)

Introduction Background

Switch Compression Master


2. PCF (new Time)

2. PCF (new Time)

Concept & Model



2. PCF (new Time)



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TTEthernet Critical-Traffic


Critical-Traffic (time-triggered and rate-constrained) is offline configured Critical-Traffic uses Ethernet destination address Critical-Traffic is determined by CT-Marker (4 Byte) Message is determined by CT-ID (2 Byte)


maximum 1518 Byte Preamble 8 Byte

CT-Adress 6 Byte CT-Marker 4 Byte

SRC-Adress 6 Bytes CT-ID 2 Byte

Ty pe 2 Byte

Payload 46 - 1500 Byte

CRC 4 Byte Standard Ethernet fields TTEthernet fields


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TTEthernet In-vehicle example application

Simulating Real-time Ethernet Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt

Chassis

TT

TT

Introduction

t Cycle

0

LIN-BUS

TTE-Switch

TTE-Switch

TT

Gateway Door

RC

BE

BE

TT

Concept & Model

BE

t 0

Cycle

RC

Diagnosis

BE

BE


t

0

Background

TT BE

0

t

Time-Triggered Message

RC

Rate-Constrained Message

BE

Best-Effort Message


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Agenda


1 Introduction


2 Background


3 Concept & Model




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Concept & Model TTEthernet integration in INET

TTE Host B


TTEthernet Application

TTEthernet Application


TTEthernet API

TTEthernet API

TTE Host A

TTE Switch

Application Layer

Introduction Background Concept & Model

TTEthernet LLC TTE-Protocol Layer

TTEthernet MAC Relay Unit

TTEthernet LLC TTE-Protocol Layer

Data Link Layer

Physical Layer


MAC

MAC

MAC

Physical Link

Physical Link

Physical Link

TTEthernet model

extended INET model

INET model


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Concept & Model TTEthernet model — Clock model


Clock: TTEthernet is a synchronised time-triggered protocol Each device has its own clock Clocks have inaccuracy (clock drift) Clock drift has significant impact on protocol behaviour


Model of clock drift must be accurate t 0 = t + δ ∗ (∆tTick + ∆tDrift )


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Concept & Model TTEthernet model — Clock model


Clock: TTEthernet is a synchronised time-triggered protocol Each device has its own clock

Introduction

Clocks have inaccuracy (clock drift)

Background

Clock drift has significant impact on protocol behaviour

Concept & Model Results & Evaluation

Model of clock drift must be accurate Cycle

Cycle



Cycle

t Event

Event Constant tick length

Event Variable drift factor


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Concept & Model TTEthernet model — Switch model


TTEthernet-Switch: Usage of the introduced clock model Combines standard INET and critical traffic switch Bypassing of Buffer in MAC-Layer to preserve priorities

Introduction Background Concept & Model Results & Evaluation Conclusion & Outlook


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Concept & Model TTEthernet Model — Switch design


TTEEthernetSwitch


TTEMACRelayUnit CT-Switch: MACRelayUnit

BE-Switch: MACRelayUnit

Introduction

MAC Port 1

MAC Port 2

MAC Port n-1

DelegatorOut

DelegatorIn

DelegatorOut

... ...

Concept & Model

DelegatorIn

DelegatorOut

DelegatorIn

DelegatorIn

DelegatorOut

Background


MAC Port n


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Concept & Model TTEthernet Model — Buffers


Incoming messages CT-Switch


BE-Switch Introduction Background Concept & Model

DelegatorOut


EtherMAC

Frame-Buffer Frame-Buffer

Outgoing message


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Concept & Model TTEthernet Model — Buffers


Incoming messages CT-Switch


BE-Switch Introduction Background

DelegatorOut

Concept & Model

RC-Buffer

BE-Buffer


EtherMAC Frame-Buffer

Outgoing message


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Agenda


1 Introduction


2 Background


3 Concept & Model




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Results Sample Topology

Simulating Real-time Ethernet Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt Introduction

TTE-Host Sender

TTE-Host Receiver

TT


TT


TT

EtherHost Sender

Switch BE

Switch BE

BE

EtherHost Receiver



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Results Latency TTEthernet and INET switch 4 5 0

S ta n S ta n T T E T T E

4 4 0 4 3 0

L a t e n c y [ µs ]

4 2 0 4 1 0

d a rd d a rd th e rn th e rn


m a x . m in . e t m a x . e t m in .


4 0 0

Concept & Model

3 9 0


3 8 0 3 7 0 3 6 0 3 5 0 0

1 0

2 0

3 0

4 0

5 0

6 0

L in k u tiliz a tio n [% ]

7 0

8 0

9 0

1 0 0


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Results Latency distribution 1 0 0

1 0 0

R e la tiv e tr a ffic p e r c la s s [% ]

9 0

9 8

8 0

1 2

7 0 6 0


1 0

Introduction

8

Background 6

Concept & Model 4


5 0 4 0 3 0


T im e - T r ig g e r e d R a te - C o n s tr a in e d B e s t-E ffo rt

Conclusion & Outlook 2

2 0 0

1 0 0

5 0 0

7 5 0

3 5 0

3 7 5

1 0 0 0

4 0 0

4 2 5

1 2 5 0

4 5 0

1 5 0 0

L a t e n c y [ µs ]

4 7 5

1 7 5 0

5 0 0

5 2 5

2 0 0 0

5 5 0

2 2 5 0

2 5 0 0


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Evaluation Comparison simulation model, analytical model and measurement


Frame simulation payload model 350 µs Schedule minimum 360.5 µs maximum 593.0 µs 9 µs Schedule minimum 19.5 µs maximum 252.0 µs

analytical model

hardware measurement


360.245 µs 592.885 µs

360 µs 592 µs

19.245 µs 251.885 µs

-

Concept & Model Results & Evaluation Conclusion & Outlook


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Agenda


1 Introduction


2 Background


3 Concept & Model




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Real-time Ethernet is a realistic candidate for in-vehicle backbone Presented model tightly conforms to TTEthernet specification Analytical model Hardware measurements

Simulation results have been carefully evaluated


Framework is currently being prepared for a first public release If you are interested visit: http://www.informatik.haw-hamburg.de/tte4inet.html Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences

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Outlook Simulating camera based vehicle-environment detection

RE Simulating Real-time Ethernet Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt Introduction Background Concept & Model Results & Evaluation Conclusion & Outlook


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RE

Thank you!

Simulating Real-time Ethernet Till Steinbach, H. Dieumo Kenfack, F. Korf, T. C. Schmidt Introduction Background Concept & Model Results & Evaluation

Thank you for your attention!


Website of research group: http://www.informatik.haw-hamburg.de/core.html Website for simulation model: http://www.informatik.haw-hamburg.de/tte4inet.html Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences

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