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AEROSPACE
STANDARD
AS6802
Issued 2011-11
Time-Triggered Ethernet
INTRODUCTION
Time-Triggered Ethernet functionality described in the SAE AS6802 standard is a Layer 2 Quality-of-Service (QoS)
enhancement for Ethernet networks. It provides the capability for deterministic, synchronous, and congestion-free
communication, unaffected by any asynchronous Ethernet traffic load.
This occurs via a fault-tolerant, self-stabilizing synchronization strategy, which helps to establish temporal partitioning and
ensures isolation of the synchronous time-critical dataflows from other asynchronous Ethernet dataflows.
By implementing this standard in network devices (network switches and network interface cards), Ethernet becomes a
deterministic network which can be shared by low-latency, low-jitter, and non-time-critical applications. This means that
distributed applications with mixed time-criticality requirements (e.g., real-time command and control, audio, video, voice,
data) can be integrated and coexist on one Ethernet network.
TABLE OF CONTENTS
1.
SCOPE .......................................................................................................................................................... 6
1.1 Purpose ......................................................................................................................................................... 7
1.2 Application ..................................................................................................................................................... 7
1.3 Interpretation ................................................................................................................................................. 8
1.4 Structure ........................................................................................................................................................ 8
2.
APPLICABLE DOCUMENTS ........................................................................................................................ 8
2.1 ARINC Publications ...................................................................................................................................... 8
2.2 IEEE Publications .......................................................................................................................................... 8
2.3 Definitions ..................................................................................................................................................... 8
3.
TIME-TRIGGERED ETHERNET OVERVIEW .............................................................................................. 9
3.1 Support for Traffic with Differing Timing Requirements ................................................................................ 9
3.1.1 Time-Triggered Dataflow Specifics ............................................................................................................. 12
3.1.2 Rate-Constrained Dataflow Specifics ......................................................................................................... 14
3.2 Transparent Synchronization ...................................................................................................................... 15
3.3 Scalable Fault Tolerance ............................................................................................................................ 17
3.3.1 Failure Modes ............................................................................................................................................. 17
3.3.2 Failure Hypothesis ...................................................................................................................................... 18
3.4 System-of-Systems Support ....................................................................................................................... 19
3.4.1 Synchronization Domains ........................................................................................................................... 19
3.4.2 Synchronization Priorities ........................................................................................................................... 19
3.5 Normative Description ................................................................................................................................. 19
3.5.1 Dataflow Requirements ............................................................................................................................... 19
3.5.2 Failure Hypothesis Requirements ............................................................................................................... 20
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