Transcript Automotive Ethernet - The IEEE Standards Association

AUTOMOTIVE ETHERNET: HOW TO HANDLE THE
DIFFERENCE BETWEEN THE STANDARD AND ITS
IMPLEMENTATION
6TH ETHERNET & IP @ AUTOMOTIVE TECHNOLOGY DAY
21.09.2016
Dr.-Ing. Thomas Kirchmeier
01
MOTIVATION.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
Page 2
01 MOTIVATION.
THE NEED OF AUTOMOTIVE ETHERNET.
Amount of in-vehicle
communication
Connectivit
yInfotainme
nt
DAS
Communication
relevant for driving
Elec. Signals
<1980
Proprietary signal based
communication
CAN
FlexRay
<1992
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
<2007
IP based communication
100BaseT1
1000BaseT1
<2016
future
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01 MOTIVATION.
BENEFITS OF AN IP BASED COMMUNICATION.
Layer 5-7 IEEE
1722
Layer 4
Layer 3
Layer 1/2
UDP
-NM
UDP
HSF
Z
SOME/I
P
TCP / UDP
AVB
SD
DHC
P
UDP
Benefits of IP protocols for Automotive.
ICM
P
ARP
IPv4
IEEE Ethernet MAC + VLAN (802.1Q)
Automotive Ethernet Physical Layer (BroadR-Reach)
 IP allows an abstraction from Layers 1 and 2 and the
use of different technologies, e.g. Ethernet, WiFi,
PLC, APIX, …
 IP makes the car part of the worldwide network.
Connects to the plant, the dealer, the backend, …
 IP is the success factor of the Internet.
Ap
p.
Ap
p.
Visible
interface and
packets
packet
Ap
p.
Middleware
Further benefits of TCP/IP protocol family.
 TCP and UDP are the established transport
protocols over IP.
 Easier integration and use of IT applications.
TCP/ IPStack
Ethernet and IP in car and
backend communication
TCP/ IPStack
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
 Allows the use of a middleware as an abstraction
makes
sense to use the TCP/IP protocol
layer to Itthe
functions.
family also in automotive.
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02
TCP/IP IS A SET OF STANDARDS,
THEIR INTERPRETATION IS AMBIGUOUS.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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02 TCP/IP IS A SET OF STANDARDS, THEIR INTERPRETATION IS
AMBIGUOUS.
EXAMPLE FOR IMPLEMENTATION DIFFERENCE BETWEEN LWIP AND
Example 1: TCP Zero Window Probing
RASPBIAN.
TCP/IP-Stack: lwIP
IUT
IUT
Command channel
Communication
channel
TCP/IP
TestSuit
e
PC
1
2
TCP/IPStack
Eth-Driver
PC
1
Source:
raspberrypi.org
UpperTeste
r
TCP/IP-Stack: Raspbian
2
3
3
4
4
1.
TCP connection is established.
1.
TCP connection is established.
2.
IUT sends some data.
2.
IUT sends some data.
3.
PC sends a TCP zero window, which
means cannot receive more data.
3.
PC sends a TCP zero window, which
means cannot receive more data.
4.
IwIP sends cyclic TCP-probes to ask the
PC if the buffer is free again.
4.
Respbian sends cyclic TCP-keep alives
to hold the TCP connection open and
valid.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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02 TCP/IP IS A SET OF STANDARDS, THEIR INTERPRETATION IS
AMBIGUOUS.
EXAMPLE FOR IMPLEMENTATION DIFFERENCE BETWEEN LWIP AND
Example 2: Listen state (TCP_CONTROL_FLAG_09)
RASPBIAN.
TCP/IP-Stack: lwIP
1
IUT
2
TCP/IP-Stack: Raspbian
PC
IUT
1
PC
1
2
2
3
3
1.
IUT is in listen state
1.
IUT is in listen state
2.
PC sends a TCP-SYN with RST-Flag,
which doesn’t make sense because a
non established TCP connection cannot
be reset.
2.
PC sends a TCP-SYN with RST-Flag,
which doesn’t make sense because a
non established TCP connection cannot
be reset.
3.
lwIP answers with a TCP-SYN, ACK in
order to establish the TCP connection.
3.
Raspbian does not answer because it
isn’t a correct request for TCP
connection.
Source:
http://www.tcpipguide.com
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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02 TCP/IP IS A SET OF STANDARDS, THEIR INTERPRETATION IS
AMBIGUOUS.
EXAMPLE DISCUSSIONS REGRINDING THE RFC INTERPRETATION.
#41494: TCP possibly violates RFC793 open since
2014
What are the consequences?
Source: http://savannah.nongnu.org/bugs/?41494
 TCP/IP specifications are not easy to understand.
 Their implementations are affected by the different
interpretations of the people who develop the stack.
Many proven TCP/IP stack implementations
exist. However, for automotive use, they
are often adapted, which causes an
additional risk for interpretation errors.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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03
TCP/IP IMPLEMENTATIONS EXIST,
BUT THEY HAVE TO BE ADAPTED.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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03 TCP/IP IMPLEMENTATIONS EXIST, BUT THEY HAVE TO BE
ADAPTED.
WHY?
Moore’s Law is still valid. e.g. iPhone
Reality for the automotive industry.
 Automotive high-end functions need similar
performance, like in the IT world.
Source:
Apple.com
Everyone is happy!
Engineer: “Marvellous, with this
increased power we can build
incredible things.
Our costumers will be impressed.”
Controller: “Marvellous, with this
increased power we can buy
cheaper. Our shareholder will be
impressed.”
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
 However, the volumes for specific parts are smaller
and therefore cause less economies of scale. In
addition automotive qualification adds to the costs.
 We have to realize more functions on cheaper
systems and have to optimize the system use.
Therefore, the TCP/IP stack needs to be
optimized.
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03 TCP/IP IMPLEMENTATIONS EXIST, BUT THEY HAVE TO BE
ADAPTED.
EXAMPLE OF AN OPTIMIZED TCP/IP STACK IN GATEWAY.
Existing TCP/IP implementation from the IT-World
HW
Ringbuffe
r
Ringbuffe
r
Ringbuffe
r
Driver
DM
A
Cop
y
Frames
DM
A
Frames
Frames
Cop
y
TCP/IP
Routing
Stack Cop Core
Segment y
PDU
s
s
Datagra
PDU
ms
s
Segment
s
Datagra
Cop
ms
y
Optimized Automotive TCP/IP implementation
HW
Ringbuffe
r
Ringbuffe
r
Ringbuffe
r
Driver + TCP/IP Stack
DM
A
Cop
Frames
DMA
Frames
Frames
Segment y
s
Datagra
ms
Segment
s
Datagra
ms
Routing
Core
PDU
s
PDU
s
− Up to 4 copy operations by using a common
TCP/IP-Stack
+ Driver and TCP/IP-Stack need to be adapted to
allow a high performance system.
− Wasting of RAM and CPU Performance of
embedded Systems
+ Application data can be sent via DMA as reference
− Implementation is platform dependent
− Every data list has to be maintained
For every embedded controller, the TCP/IP stack has to be optimized to save resources and costs.
Source: As referred to in presentation of Matthias Kessler, 1st Automotive Ethernet Congress, February
04-05, 2015, Munich
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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04
EXAMPLE TEST RESULTS.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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04 EXAMPLE TEST RESULTS.
RESULTS OF THE 1. TESTRUN (ANONYMIZED).
ECU 1
ECU 2
ECU 3
µController Type
Embedded
Embedded
IT CPU
TCP/IP-Stack
µIP
lwIP
Debian
Stack optimized?
Yes
Yes
No
TCP
(pass / fail)
167 / 73
163 / 77
223 / 17
IP
(pass / fail)
28 / 3
28 / 3
32 / 0
UDP
(pass / fail)
34 / 14
32 / 16
41 / 1
ARP
(pass / fail)
21 / 0
21 / 0
41 / 4
6 / 12
not needed
not needed
AutoIP (pass / fail)
Testing is the key to reach a reliable communication between different ECUs in a network.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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04 EXAMPLE TEST RESULTS.
TC8 TESTING PROCESS USED BY BMW.
Testing process of OPEN Alliance TC8.
ECU test
spec.
Test House
A
OPEN
Alliance
TC8
Feedback
Ethernet
ECU test
report
Benefits.
ECU test
spec.
Test House
B
Ethernet
ECU test
report
Tier1 X
Tier1 Y
ECU test
report
ECU test
report
OEM
Network ECU
integration 1
goa
reliable
l
communication in
network
ECU
2
Network
tests
Source: OPEN Alliance TC8, Document Test Process and ECU Test Specification v1.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
 Single point of truth of TCP/IP test specification with
automotive content.
 Comparable test results of different TCP/IP stacks.
 Harmonization of different TCP/IP stack
implementations.
 Continuous improvement of the test specification
based on the feedback of the Test Houses.
 Possibility to adapt or add test cases in order to
meet the state of the art of the requirements to the
TCP/IP stack in future, e.g. security and/or safety
aspects.
We can concentrate on the customer
functions.
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05
CONCLUSION.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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05 SUMMARY.
 One of the advantages of using automotive Ethernet is reuse of protocols on higher application
layers, like TCP/IP.
 However, the devil is in the details:
 TCP/IP specifications as such are not unambiguous and despite the years of deployment
deviations in interpretations can cause interoperability issues.
 The trade off between cost and performance always requires an optimization of all system
components. In order to keep the processing units small, the TCP/IP stack implementations are
being optimized for the automotive use case.
 These optimizations are not standardized and platform dependent and can also result in
interoperability issues.
 Conformance testing can identify and solve potential interoperability issues.
 The OPEN Alliance TC8 developed a respective test process.
 The
examples
this| 6thpresentation
showDaythe importance of this test process.
Dr.-Ing.
Thomas
Kirchmeier, BMW Groupof
| 21.09.2016
Ethernet & IP @ Automotive Technology
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THANK YOU FOR YOUR ATTENTION.
Dr.-Ing. Thomas Kirchmeier, BMW Group | 21.09.2016 | 6th Ethernet & IP @ Automotive Technology Day
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