SAE AS6802A-2023 PDF

Full title and description

SAE AS6802A-2023 — Time-Triggered Ethernet. This Aerospace Standard defines a fault‑tolerant synchronization strategy and supporting algorithms for building and maintaining a globally synchronized time base across distributed end systems and switches to enable time‑triggered (synchronous) traffic to coexist with asynchronous Ethernet traffic in mixed‑criticality embedded systems (avionics, vetronics and other mission‑critical systems).

Abstract

AS6802A specifies clock synchronization algorithms, clique detection, startup/restart behaviour and self‑stabilization mechanisms to provide deterministic delivery and bounded jitter for time‑triggered Ethernet frames while allowing standard best‑effort Ethernet and other traffic types on the same physical network. The standard supports partitioning and isolation of critical communications and includes requirements to achieve scalable fault tolerance in distributed networked systems.

General information

• Status: Current / Active (revision A of AS6802).
• Publication date: 14 February 2023.
• Publisher: SAE International.
• ICS / categories: Information technology — Networking and OSI data‑link layer (ICS 35.110; related: 35.100.20 Data link layer) and aerospace/avionics applications.
• Edition / version: AS6802A (2023 revision; supersedes the original AS6802 specification).
• Number of pages: 106 pages (typical published PDF/hardcopy length).

Scope

This standard defines the synchronization strategy and associated protocols for Time‑Triggered Ethernet (TTEthernet) implementations used to support synchronous (time‑triggered) and asynchronous traffic classes on the same Ethernet network. It covers the algorithms needed for clock synchronization, clique detection, start‑up and restart behaviour, fault‑tolerance design principles, and mechanisms to compensate for latency and jitter introduced by mixed traffic. AS6802A is intended to enable deterministic, partitioned communication for avionics and other safety/mission‑critical distributed systems.

Key topics and requirements

• Fault‑tolerant distributed clock synchronization algorithm and parameters for microsecond‑level precision.
• Clique detection and membership management to identify and tolerate faulty nodes or partitions.
• Startup, restart and re‑synchronization procedures to achieve safe transient behaviour.
• Time partitioning and bandwidth allocation to guarantee deterministic transmission windows for time‑triggered frames.
• Coexistence rules for time‑triggered, rate‑constrained, and best‑effort traffic on the same physical Ethernet network.
• Requirements and guidance for implementation in end systems and switches to achieve scalable fault tolerance.
• Interoperability considerations with avionics communications architectures (references to ARINC/AFDX and related avionics practices are included in normative/informative references).

Typical use and users

Engineers and architects designing deterministic networked systems in aerospace (avionics), military vehicle electronics (vetronics), industrial control and energy systems. Typical users include avionics OEMs and suppliers, embedded systems developers, network switch and NIC vendors, system integrators, safety and certification engineers, and researchers working on time‑sensitive networking and deterministic Ethernet.

Related standards

Key related standards and families include IEEE 802.3 (Ethernet), IEEE 802.1 time‑synchronization and TSN (for example IEEE 802.1AS and IEEE 802.1Q TSN profiles), ARINC 664 (AFDX), ARINC 653 (partitioning for avionics), and the original SAE AS6802 (prior edition). Implementations frequently reference these specifications for lower‑layer Ethernet behaviour, higher‑level partitioning and avionics integration.

Keywords

Time‑Triggered Ethernet, TTEthernet, deterministic Ethernet, clock synchronization, clique detection, time partitioning, avionics networking, mixed‑criticality, SAE AS6802A, TSN interoperability.

FAQ

Q: What is this standard?

A: SAE AS6802A-2023 is an Aerospace Standard titled "Time‑Triggered Ethernet" that defines the synchronization strategy and runtime behaviour required to support deterministic, time‑triggered communication on Ethernet networks used in avionics and other safety‑critical systems.

Q: What does it cover?

A: It covers algorithms and procedures for distributed clock synchronization, clique detection (fault isolation), startup/restart behaviour, and mechanisms for mixing synchronous time‑triggered traffic with asynchronous (best‑effort) Ethernet traffic while bounding latency and jitter. It also provides implementation guidance for end systems and switches to achieve fault tolerance and scalability.

Q: Who typically uses it?

A: Avionics and embedded systems designers, network hardware and software vendors, system integrators, and certification/safety engineers who need deterministic, time‑synchronized networking for mixed‑criticality applications (for example commercial and military avionics, vetronics and industrial control systems).

Q: Is it current or superseded?

A: AS6802A (published February 14, 2023) is the current revision (revision A) of the original AS6802 specification (original work dating from 2011). The 2023 document is the active edition at the time of publication and supersedes the earlier AS6802 material.

Q: Is it part of a series?

A: AS6802A is part of SAE's family of aerospace standards addressing avionics systems and networking practices; it is commonly used alongside Ethernet and avionics standards (IEEE 802.3, IEEE 802.1 AS/TSN, ARINC 664 and ARINC 653) to build complete avionics networking solutions.

Q: What are the key keywords?

A: Time‑Triggered Ethernet, TTEthernet, deterministic networking, clock synchronization, clique detection, time partitioning, mixed‑criticality, SAE AS6802A.