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Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
Deterministic Ethernet SAE AS6802
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Deterministic Ethernet SAE AS6802

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  • 1. Deterministic Ethernet:SAE AS6802 "Time-Triggered Ethernet"Join “Deterministic Ethernet” Group @ LinkedInhttp://www.linkedin.com/groups?gid=3862779Visit SAE AS-2D2“Deterministic Ethernet and Unified Networking” Committeehttp://www.sae.org/servlets/works/committeeHome.do?comtID=TEAAS2D 1
  • 2. SAE AS6802: „Time-TriggeredEthernet“ (TTEthernet) Public specification available since 2008 IP designed to DO-254/DO-178B Level A ◦ formal proof of protocol algorithms used for IEC61508 SIL-rated systems Standardization at SAE ◦ SAE standardization project started in 2009 ◦ SAE Standard release in November 2011 ◦ http://standards.sae.org/as6802 2
  • 3. What is „Time-Triggered“? Predictable (deterministic) communication ◦ Fixed latency, µs-jitter, TDMA System timebase available, but no master clock (alignment of local clocks in µs!) Autonomous network operation ◦ based on scheduled communication and system time Examples: ◦ FlexRay ◦ TTP (SAE AS6003) ◦ TTEthernet (SAE AS6802) 3
  • 4. What is Ethernet, really? A family of frame-based standards for LAN/MAN networks by IEEE802 ◦ Standard physical medium ◦ Set of medium access control rules with fair arbitration ◦ Variable size packets in Ethernet format 4
  • 5. SAE AS6802: „Time-TriggeredEthernet“ (TTEthernet) The objective was to: ◦ make Ethernet viable for any time-, safety- and mission- critical embedded system application (SAE AS6802 is a Layer 2 protocol service) ◦ … and retain asynchronous communication capabilities The objective was NOT to: ◦ create yet another real-time industrial Ethernet network, that is incompatible with IEEE802.3 or standard Ethernet LAN In fact it is a service … ◦ compare it to deterministic VLAN messaging with fixed end-to-end latency and µs-jitter! 5
  • 6. SAE AS6802: A Layer 2 QoS EnhancementTime-Triggered Ethernet (TTEthernet) Allows integration of low-latency, low-jitter and standard LAN applications 6
  • 7. SAE AS6802: A Layer 2 QoS Enhancement Time-triggered extensions (Layer 2) implemented in an Ethernet switch enable deterministic unified networking ◦ Synchronous startup ◦ Synchronous recovery ◦ Robust fault-tolerant distributed clock ◦ Foundation for synchronous communication and robust bandwidth partitioning in Ethernet networks 7
  • 8. Summary:System Designer Perspective SAE AS6802 is just another Ethernet service Add SAE AS6802 service to Ethernet switch ◦ capabilities to design Ethernet-based time-, safety- and mission critical system ! Add other comptible IEEE802.1 Layer 2 services to gain specific capabilities and support (deterministic) unified networking ◦ VLAN(IEEE802.1Q), DCB, IEEE1588/IEEE802.1AS, Rate-contrained services with traffic shaping, etc. Use Ethernet as a deterministic network capable of handling different types of time-critical traffic 8
  • 9. Deterministic Ethernet:SAE AS6802 "Time-Triggered Ethernet“Capabilities 9 PAPER #
  • 10. Capabilities: DistributedFault-tolerant Synchronization Robust algorithm based on exchange of asynchronous IEEE802.3 messages Synchronizes local clocks – system time (!) ◦ no wall clock (external time source - e.g. GPS) required Fail-operational: ◦ tolerates multiple faults ◦ tolerates byzantine synchronization faults ◦ no search for best master (distributed clock!) Provides defined worst-case synchronous startup & recovery time (in ms) 10
  • 11. Capabilities:Synchronous Communication System time available on switches and endsystems ◦ Scheduled traffic can have fixed latency and µs-jitter ◦ Switch knows when the message is forwarded 11
  • 12. Capabilities:Deterministic Unified Ethernet Synchronous and Asynchronous Traffic „Virtual links“ are forwarded through 100BASE-TX, 1000BASE-CX, 1000BASE-SX or other Ethernet physical layer connections 12
  • 13. Capabilities: Robust Partitioning forDeterministic Unified Ethernet Mechanisms: ◦ Switch knows the traffic schedule for synchronous (TT) traffic ◦ Switch knows about properties of time-sensitive traffic and possible time-violations e.g. for AFDX / ARINC664 (e.g. rate constrained – BAG, periodicity) ◦ Switch knows when the best effort (asynchronous) traffic can be scheduled to prevent violation of temporal constraints for RC and TT Configuration Configuration for TT Traffic for RC Traffic Synchronous (TT) Traffic Time-Sensitive Traffic (RC) Scheduling Output Port Logic Asynchronous (Priority-Driven and/or Lossless) (Switch) 13
  • 14. Capabilities:Deterministic Unified Ethernet What if synchronous links (VLs) are reserved, but the message is not sent? ◦ … ECU / LRU is not installed ◦ … Function is currently inactive Dynamic Bandwidth Release: immediate availability for asynchronous traffic 14
  • 15. Comparison with other Ethernetstandards 15 PAPER #
  • 16. Ethernet in Critical EmbeddedSystems Industrial RT Ethernet (ProfiNet RT/IRT, Time-Critical, PowerLink, Ethernet/IP CIP Sync, EtherCAT, ...) Mission-Sensitive Lossless, IEEE DCB Loss-sensitive, Time-sensitive, IEEE AVB Mission-Critical ARINC 664 Part 7 Deterministic, Time-critical, SAE AS6802 Safety-critical, (TTEthernet) Mission-critical 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 16
  • 17. Positioning: SAE AS6802 forDeterministic Unified Ethernet QoS in shared Ethernet networks 17
  • 18. TTEthernet Switch withSAE AS6802 / ARINC664-P7 TTEthernet Switch Services Used QoS Protocol Services TTEthernet RC TT Switch Behavior BE (ARINC664) (SAE AS6802) RC Switch X - - RC Switch w/ A/V and hard-RT X X - TTEthernet Switch - X - (synch. AS6802 comm. only) Plain TTEthernet Switch - X X IEEE802.3 switch - - X Mixed Criticality TTEthernet Switch X X X 18
  • 19. Positioning: SAE AS6802 forDeterministic Unified Ethernet QoS in shared Ethernet networks 19
  • 20. SAE AS6802 and RT-Ethernet 21
  • 21. SAE AS6802 in IEC61850 Context GOOSE Messages (low-latency, critical) can be sent via time-triggered messgaes Protection Control & Protection Data Data Data Data 22
  • 22. Impact on System Design Mirko Jakovljevic, TTTech / SAE AS-2D 23 PAPER #
  • 23. Why DeterministicTime-Triggered Networks ? Network capabilities impact architecture and application design ◦ the number of ECUs, wiring and weigth ◦ use of network bandwidth and computing resources ◦ level of functional integration ◦ system and application complexity cost of SW/HW design and integration ◦ maintenance, reuse and upgrades ◦ obsolescence management ◦ certification ◦ … 24
  • 24. Advanced System Integration Distributed Integrated Modular Architectures (DIMA) Statistical Multiplexing Many high- and low-level functions share distributed computing and networking resources TDMA Multiplexing gh Federated Integrated Modular Hi !! y ! Architectures er MA (e.g. IMA) :V IComputing Resources v el an Le is ?(one function per box) Many higher level functions on n em tio ystNetworking Resources one processing module ra S(physically separated te g le unidirectional links) Additional low-level functions via I n ho How DIMA covers networked RDCs W this gap? gap? Integ r vel: Hig h Fede ation Lev Integr ation Le rated el Arch : Very Lo Integration Level: Low itect ures w 25
  • 25. Resource Use & Complexity Reduction Maximize use of network bandwidth and computing resources for critical embedded functions ◦ Reduce uncertainity, jitter and unintended system states Improve functional alignment (and separation!) ◦ Simplified sensor fusion ◦ Simplified distributed processing ◦ Simplified redundancy management 26
  • 26. Integrating many functions on fewECUs Emulate distributed computer / reflective memory Integrate critical and non-critical functions 27
  • 27. SAE AS6802 in Critical Applications Robust TDM-style bandwidth partitioning (Hard) Real-time operation Strictly deterministic system operation Predictable computing and networking resource sharing Alignment of different functions accross the systems Design of advanced system architectures for minimizing SWaP System complexity reduction (system state explosion!) 28
  • 28. SAE AS6802 in Critical Applications If we managed to go from federated to integrated architectures … ◦ Read: time/space partitioning at module level … we can manage transition to „distributed AND integrated“ architectures ◦ Read: time/space partitioning at module level plus time partitioning at network level system-level partitioning (of all computing and networking resources) Predictable virtualization of complex embedded systems 29
  • 29. New activities on SAE AS-2D agenda? SAE AS6802 (TTEthernet) ◦ Scheduling and system design ◦ Application Handbook ◦ Complexity reduction ◦ Linear Deterministic Networks ◦ Closer work with IEEE? 30
  • 30. Q&AVisit Deterministic Ethernet / LinkedIn Group (!!) Mirko Jakovljevic, TTTech / SAE AS-2D mirko.jakovljevic@tttech.com 31 PAPER #

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