TTEthernet

The Time-Triggered Ethernet (SAE AS6802) (also known as TTEthernet or TTE) standard defines a fault-tolerant synchronization strategy for building and maintaining synchronized time in Ethernet networks, and outlines mechanisms required for synchronous time-triggered packet switching for critical integrated applications and integrated modular avionics (IMA) architectures. SAE International released SAE AS6802 in November 2011.

Time-Triggered Ethernet network devices are Ethernet devices which at least implement:

• SAE AS6802 synchronization services for advanced integrated architectures, fail-operational and safety-critical systems
• time-triggered traffic flow control with traffic scheduling
• per-flow policing of packet timing for time-triggered traffic
• robust internal architecture with traffic partitioning

TTEthernet network devices are standard Ethernet devices with additional capability to configure and establish robust synchronization, synchronous packet switching, traffic scheduling and bandwidth partitioning, as described in SAE AS6802. If no time-triggered traffic capability is configured or used, it operates as full duplex switched Ethernet devices compliant with IEEE802.3 and IEEE802.1 standards.

In addition, such network devices implement other deterministic traffic classes to enable mixed-criticality Ethernet networking. Therefore, TTEthernet networks are designed to host different Ethernet traffic classes without interference.

TTEthernet device implementation expands standard Ethernet with services to meet time-critical, deterministic or safety-relevant requirements in double- and triple-redundant configurations for advanced integrated systems. TTEthernet switching devices are used for integrated systems and safety-related applications primarily in the aerospace, industrial controls and automotive^[1] applications.

TTEthernet has been selected by NASA and ESA as the technology for communications between the Orion MPCV and the European Service Module, and is described by the ESA as being "prime choice for future launchers allowing them to deploy distributed modular avionics concepts".^[2] It has also been selected as the backbone network for NASA's Lunar Gateway^[3] to which ESA is a key stakeholder.

As an increasingly used network architecture in the space industry, European Cooperation for Space Standardization published ECSS-E-ST-50-16C on September 30, 2021.^[4]