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TTEthernet (SAE AS6802) is a computer network technology marketed by TTTech Computertechnik AG "for safety-related applications primarily in transportation industries and industrial automation."[1]


TTEthernet expands classical Ethernet with services to meet time-critical, deterministic or safety-relevant conditions. It claims to be compatible with IEEE 802.3 standards and integrate with other Ethernet networks. Three message types are provided:[2]

  • Time-triggered messages are sent over the network at predefined times and take precedence over all other message types. The occurrence, temporal delay and precision of time-triggered messages are predefined and guaranteed. The messages have as little delay on the network as possible and their temporal precision is as accurate as necessary. However, "synchronized local clocks are the fundamental prerequisite for time-triggered communication".[3]
  • Rate-constrained messages are used for applications with less stringent determinism and real-time requirements. These messages guarantee that bandwidth is predefined for each application and delays and temporal deviations have defined limits.
  • Best-effort messages follow the usual Ethernet policy. There is no guarantee whether and when these messages can be transmitted, what delays occur and if messages arrive at the recipient. Best-effort messages use the remaining bandwidth of the network and have lower priority than the other two types.
Three message types

This compares to the eight quality of service classes defined by the IEEE P802.1p task group in 1998 and IEEE 802.1Q added to the standard protocol. In 2008 the company announced Honeywell would apply the technology to applications in the aerospace and automation industry.[4] In 2010 a switch-based implementation was shown to perform better than shared bus systems such as FlexRay for use in automobiles.[5]

TTEthernet versus TT-Ethernet[edit]

The academic TT-Ethernet project was a joint research project between the Vienna University of Technology and TTTech. First results were published in 2005.[6] The project proposed a preemptive switch and built a prototype for 100 Megabit/second links in 2007. This switch identified the reception of a time-triggered message based on an identifier within the message and preempted other messages under transmission to free the outgoing ports for the time-triggered message.[7]

Research continued within a joint industrial development between TTTech and Honeywell. TTEthernet was the industrial further development of the research. Objectives were extended towards scalable fault-tolerance and a finer classification of event-triggered messages into rate-constrained and best-effort traffic classes.[2]

See also[edit]


  1. ^, retrieved 13 July 2014.
  2. ^ a b "TTEthernet – A Powerful Network Solution for All Purposes" (PDF). Marketing whitepaper. TTTech Computertechnik AG. 2009. Retrieved March 28, 2014. [dead link]
  3. ^ Wilfried Steiner and Bruno Dutertre, SMT-Based Formal Verification of a TTEthernet Synchronization Function, S. Kowalewski and M. Roveri (Eds.), FMICS 2010, LNCS 6371, pp. 148–163, 2010.
  4. ^ "New Products: Ethernet Platform". News release in Avionics magazine. April 1, 2008. Retrieved June 9, 2011. 
  5. ^ T. Steinbach, F. Korf, T. C. Schmidt (May 18, 2010). "Comparing time-triggered Ethernet with FlexRay: An evaluation of competing approaches to real-time for in-vehicle networks". 8th IEEE International Workshop on Factory Communication Systems (WFCS): 199–202. doi:10.1109/WFCS.2010.5548606. ISBN 978-1-4244-5460-0. 
  6. ^ Hermann Kopetz; Astrit Ademaj; Petr Grillinger; Klaus Steinhammer (May 2005). "The Time-Triggered Ethernet (TTE) Design". 8th IEEE International Symposium on Object-oriented Real-time distributed Computing (Seattle, Washington: TU Wien): 22–33. doi:10.1109/ISORC.2005.56. Retrieved December 5, 2010. 
  7. ^ Astrit Ademaj; Hermann Kopetz. "Time-Triggered Ethernet and IEEE 1588 Clock Synchronization". International IEEE Symposium on Precision Clock Synchronization for Measurement, Control and Communication (TU Wien): 41–43. doi:10.1109/ISPCS.2007.4383771. Retrieved December 5, 2010. 

External links[edit]