Performance Analysis of Time-Triggered Ether-Networks Using Off-The-Shelf-Components

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Performance Analysis of Time-Triggered

Ether-Networks Using

Off-The-Shelf-Components

AMICS Workshop 2011

Florian Bartols, Till Steinbach, Franz Korf, Thomas C. Schmidt

{florian.bartols,till.steinbach,korf,schmidt}

@informatik.haw-hamburg.de

Hamburg University of Applied Sciences

March, 31st 2011

RE

Hochschule für Angewandte Wissenschaften Hamburg

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Performance Analysis of TT-Ether-Networks Florian Bartols, T. Steinbach, F. Korf, T. C. Schmidt Introduction Motivation

Related Work & Background Implementing the Measurement Facility Validation & Measurements Conclusion & Outlook

RE

Agenda

1 Introduction

Motivation

2 Related Work & Background

3 Implementing the Measurement Facility

4 Validation & Measurements

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Hamburg University of Applied Sciences

Performance Analysis of TT-Ether-Networks Florian Bartols, T. Steinbach, F. Korf, T. C. Schmidt Introduction Motivation Related Work & Background Implementing the Measurement Facility Validation & Measurements Conclusion & Outlook

RE

Introduction

Motivation

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RE

Introduction

Motivation

Real-time Ethernet in automotive applications:

In-vehicle networks are very complex

New automotive applications require more

bandwidth

Real-time Ethernet is widely deployed in backbones

of industrial plants

(5)

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Introduction

Motivation

Low cost performance analysis with time-triggered packet

generation:

Missing performance analyzer instruments in tool

chain

Tools for standard switched Ethernet are not suitable

Flexible embedded pc based tools gain importance

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Performance Analysis of TT-Ether-Networks Florian Bartols, T. Steinbach, F. Korf, T. C. Schmidt Introduction

Related Work & Background Ethernet Measurement Approaches Real-time Ethernet Implementing the Measurement Facility Validation & Measurements Conclusion & Outlook

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Agenda

1 Introduction

2 Related Work & Background

Ethernet Measurement Approaches

Real-time Ethernet

3 Implementing the Measurement Facility

4 Validation & Measurements

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Performance Analysis of TT-Ether-Networks Florian Bartols, T. Steinbach, F. Korf, T. C. Schmidt Introduction Related Work & Background Ethernet Measurement Approaches Real-time Ethernet Implementing the Measurement Facility Validation & Measurements Conclusion & Outlook

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Related Work

Ethernet Measurement Approaches

Distinction between software and hardware based

measurements

Collection on one network port only

Distributed measurement with synchronized

timebase

One physical clock and several network ports

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RE

Related Work

Ethernet Measurement Approaches

Distinction between software and hardware based

measurements

Collection on one network port only

Analyzer

NuT

Distributed measurement with synchronized

timebase

(9)

RE

Related Work

Ethernet Measurement Approaches

Distinction between software and hardware based

measurements

Collection on one network port only

Distributed measurement with synchronized

timebase

Analyzer

NuT

Analyzer

One physical clock and several network ports

(10)

RE

Related Work

Ethernet Measurement Approaches

Distinction between software and hardware based

measurements

Collection on one network port only

Distributed measurement with synchronized

timebase

One physical clock and several network ports

Analyzer

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RE

Background

Real-time Ethernet

3 strategies to enable real-time characteristics on

Ethernet-based networks

Token-based systems

Used in Ethercat in process automation

Bandwidth limiting systems

For instance AFDX in Airplanes (A380 and Boeing

787)

Time-triggered systems

Automotive industry (FlexRay) and process

automation (Profinet)

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Background

Real-time Ethernet

3 strategies to enable real-time characteristics on

Ethernet-based networks

Token-based systems

Used in Ethercat in process automation

Bandwidth limiting systems

For instance AFDX in Airplanes (A380 and Boeing

787)

Time-triggered systems

Automotive industry (FlexRay) and process

automation (Profinet)

(13)

RE

Background

Real-time Ethernet

3 strategies to enable real-time characteristics on

Ethernet-based networks

Token-based systems

Used in Ethercat in process automation

Bandwidth limiting systems

For instance AFDX in Airplanes (A380 and Boeing

787)

Time-triggered systems

Automotive industry (FlexRay) and process

automation (Profinet)

(14)

RE

Background

Real-time Ethernet

3 strategies to enable real-time characteristics on

Ethernet-based networks

Token-based systems

Used in Ethercat in process automation

Bandwidth limiting systems

For instance AFDX in Airplanes (A380 and Boeing

787)

Time-triggered systems

Automotive industry (FlexRay) and process

automation (Profinet)

(15)

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Background

Time-Triggered Ethernet

3 Traffic Classes in TTEthernet

1 Time-Triggered

Highest priority and used for hard real-time data

Strictest requirements in transmission

2 Rate-Constrained

Also suitable for real-time communication

Complies to the AFDX protocol

3 Best-Effort

Standard Ethernet traffic

No guarantee in transmission

Time synchronization for a global time base

Works transparent to the Ethernet-Protocol-Layer

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Background

Time-Triggered Ethernet

3 Traffic Classes in TTEthernet

1 Time-Triggered

Highest priority and used for hard real-time data

Strictest requirements in transmission

2 Rate-Constrained

Also suitable for real-time communication

Complies to the AFDX protocol

3 Best-Effort

Standard Ethernet traffic

No guarantee in transmission

Time synchronization for a global time base

Works transparent to the Ethernet-Protocol-Layer

(17)

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Background

Time-Triggered Ethernet

3 Traffic Classes in TTEthernet

1 Time-Triggered

Highest priority and used for hard real-time data

Strictest requirements in transmission

2 Rate-Constrained

Also suitable for real-time communication

Complies to the AFDX protocol

3 Best-Effort

Standard Ethernet traffic

No guarantee in transmission

Time synchronization for a global time base

Works transparent to the Ethernet-Protocol-Layer

(18)

RE

Background

Time-Triggered Ethernet

3 Traffic Classes in TTEthernet

1 Time-Triggered

Highest priority and used for hard real-time data

Strictest requirements in transmission

2 Rate-Constrained

Also suitable for real-time communication

Complies to the AFDX protocol

3 Best-Effort

Standard Ethernet traffic

No guarantee in transmission

Time synchronization for a global time base

Works transparent to the Ethernet-Protocol-Layer

(19)

RE

Background

Time-Triggered Ethernet

3 Traffic Classes in TTEthernet

1 Time-Triggered

Highest priority and used for hard real-time data

Strictest requirements in transmission

2 Rate-Constrained

Also suitable for real-time communication

Complies to the AFDX protocol

3 Best-Effort

Standard Ethernet traffic

No guarantee in transmission

Time synchronization for a global time base

Works transparent to the Ethernet-Protocol-Layer

(20)

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Background

Time-Triggered Ethernet

TTE-switch BE 0 diagnosis BE BE t t TT TT RC BE BE BE t TT Time-Triggered Message RC BE Rate-Constrained Message Best-Effort Message TTE-switch LIN gateway door RC 0 LIN-BUS t chassis TT TT 0 cycle cycle 0

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Performance Analysis of TT-Ether-Networks Florian Bartols, T. Steinbach, F. Korf, T. C. Schmidt Introduction Related Work & Background

Implementing the Measurement Facility

Concept

Accessing the Current System Time Assigning Timestamps to Frames

Validation & Measurements Conclusion & Outlook

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Agenda

1 Introduction

2 Related Work & Background

3 Implementing the Measurement Facility

Concept

Accessing the Current System Time

Assigning Timestamps to Frames

4 Validation & Measurements

5 Conclusion & Outlook

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Performance Analysis of TT-Ether-Networks Florian Bartols, T. Steinbach, F. Korf, T. C. Schmidt Introduction Related Work & Background Implementing the Measurement Facility

Concept

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Implementing the Measurement Facility

Problem statement

Available OS tools:

Tools running in Userspace (e.g. ping, traceroute)

Precision in milliseconds provided by OS

Scheduling and hardware-layer produce overhead

OS tools measure round-trip-time

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Concept

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Implementing the Measurement Facility

Solution

Our approach:

Measurement on a low-level base → Kernelspace in

Linux

RT-Linux utilization for enhanced interrupt handling

Exact timing behavior by using special functions

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Concept

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Implementing the Measurement Facility

Concept

TT-Network

under test

Hardware Hardware

_{Physical Layer}

BE Device Driver Timestamping

Kernelspace

Application

Userspace

TT Device Driver Timestamping

TTEthernet Stack

Assembling Calculation

(25)

Concept

Accessing the Current System Time

Assigning Timestamps to Frames

RE

Implementing the Measurement Facility

Accessing the Current System Time

Methods

Pre

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Concept

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Implementing the Measurement Facility

Accessing the Current System Time

Methods

Pre

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C

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Concept

RE

Implementing the Measurement Facility

Accessing the Current System Time

Methods

Pre

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iffi

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C

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Concept

RE

Implementing the Measurement Facility

Accessing the Current System Time

Methods

Pre

ci

si

o

n

J

iffi

e

s

C

o

u

n

te

r

d

o

_

g

e

tti

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e

o

fd

a

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()

g

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Concept

Assigning Timestamps to Frames Validation & Measurements Conclusion & Outlook

RE

Implementing the Measurement Facility

Assigning Timestamps to Frames

2 approaches to get timing information of a single frame

1 Storing information in Kernelspace

High implementation cost (limited Kernel functions)

Additional information has be stored

2 Modifying Ethernet frames with timestamps

A lightweight approach

Assigning timestamps to frames in an easy way

Measurement can be done promptly without

reading and storing information

Ethernet Frame

Header Payload CRC

Send Recv Seq

Data Measurement

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Concept

Assigning Timestamps to Frames Validation & Measurements Conclusion & Outlook

RE

Implementing the Measurement Facility

Assigning Timestamps to Frames

2 approaches to get timing information of a single frame

1 Storing information in Kernelspace

High implementation cost (limited Kernel functions)

Additional information has be stored

2 Modifying Ethernet frames with timestamps

A lightweight approach

Assigning timestamps to frames in an easy way

Measurement can be done promptly without

reading and storing information

Ethernet Frame

Header Payload CRC

Send Recv Seq

Data Measurement

(31)

Validation & Measurements

Validating the Approach Measurement Results

Conclusion & Outlook

RE

Agenda

1 Introduction

2 Related Work & Background

3 Implementing the Measurement Facility

4 Validation & Measurements

Validating the Approach

Measurement Results

5 Conclusion & Outlook

(32)

Performance Analysis of TT-Ether-Networks Florian Bartols, T. Steinbach, F. Korf, T. C. Schmidt Introduction Related Work & Background Implementing the Measurement Facility Validation & Measurements

Validating the Approach

Measurement Results

RE

Validation

Sample Measurement

3ms System Schedule for each TT-Frame

350µs static switch delay

BE

TT

Server

Application send timestamp receive timestamp

3

2

1

measurement frames

4

3 ms system schedule

TT-Network

under test

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Measurement Results

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Validation

Sample Measurement

0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0 5 2 0 5 4 0 5 6 0 5 8 0 6 0 0

L

a

te

n

c

y

(

µ

s

)

F r a m e s i z e ( B y t e )

s t d . c o n f i g

Observation: A specific hardware and driver delay

has to be substracted for each measurment

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Measurement Results

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Validation

Sample Measurement

0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0 5 2 0 5 4 0 5 6 0 5 8 0 6 0 0

L

a

te

n

c

y

(

µ

s

)

F r a m e s i z e ( B y t e )

s t d . c o n f i g

6 4 B y t e t h r e s h o l d

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Measurement Results

RE

Validation

Applied Validation Approaches

1 High precision Ethernet analyzer tool

t1 t2

Ethernet

Analyzer

t = t2 - t1 port1 port2

BE

TT

Server

Application

3

4 TT-Network

under test

duplicate measurement frames

2

1

2 Mathematical framework

Analytical method to calculate latency, bandwidth

and jitter

(36)

Measurement Results

RE

Validation

Applied Validation Approaches

1 High precision Ethernet analyzer tool

t1 t2

Ethernet

Analyzer

t = t2 - t1 port1 port2

BE

TT

Server

Application

3

4 TT-Network

under test

duplicate measurement frames

2

1

2 Mathematical framework

Analytical method to calculate latency, bandwidth

and jitter

(37)

Measurement Results

RE

Validation

Results in Comparison

measurement

hardware

mathematical

approach

sniffing

model

min. framelength

355µs

364µs

355.125µs

max. framelength

471µs

479µs

471.445µs

Difference of 9µs is due to the used duplication switch

measurement

hardware

mathematical

approach

sniffing

model

min. framelength

355µs

355.125µs

max. framelength

471µs

470µs

471.445µs

(38)

Measurement Results

RE

Validation

Results in Comparison

measurement

hardware

mathematical

approach

sniffing

model

min. framelength

355µs

364µs

355.125µs

max. framelength

471µs

479µs

471.445µs

Difference of 9µs is due to the used duplication switch

measurement

hardware

mathematical

approach

sniffing

model

min. framelength

355µs

355.125µs

max. framelength

471µs

470µs

471.445µs

(39)

Measurement Results Conclusion & Outlook

RE

Measurements

Latency Comparison COTS switch and TTEthernet Switch

(40)

Measurement Results Conclusion & Outlook

RE

Measurements

(41)

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Agenda

1 Introduction

2 Related Work & Background

3 Implementing the Measurement Facility

4 Validation & Measurements

5 Conclusion & Outlook

(42)

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Conclusion & Outlook

Conclusion:

Performance analysis with COTS in single-digit

microseconds precision

Synchronized packet generation

Utilization of RT-Linux, modified device drivers and

TTEthernetstack

Outlook:

Validation using hardware with specifically low

receive and copy delay

Adjustment of this approach on an ARM-based

micro controller to increase resolution

(43)

RE

Conclusion & Outlook

Conclusion:

Performance analysis with COTS in single-digit

microseconds precision

Synchronized packet generation

Utilization of RT-Linux, modified device drivers and

TTEthernetstack

Outlook:

Validation using hardware with specifically low

receive and copy delay

Adjustment of this approach on an ARM-based

micro controller to increase resolution

(44)

RE

Thank you!

Thank you for your attention!

Website of research group:

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Background

TTEthernet Synchronization Method

1. PCF (time)

2. PCF (new Time)

End System

Sync Client

End System

Sync Master

Switch

Compression

Master

End System

Sync Master

End System

Sync Client

2. PCF (new Time)

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