For many Ethernet-based real-time systems, such as those from automotive, avionics, and industry automation domains, fault tolerance is emerged as an essential requirement for enabling fail-safe or fail-operational behavior. Consequently, the IEEE 802.1CB-2017 standard was published. It is currently the only available time-sensitive networking group standard offering protection against transmission errors. It tackles these faults by preventively replicating the frames and transmitting redundant copies via different paths to the destination. However, in contrast to its obvious advantages, the standard contains some pitfalls: most notably, it lacks protection mechanisms against inadequate configurations, which can not only invalidate the intended increase in reliability but even actively jeopardize the safety of the network. Due to the lack of alternative mechanisms, it is crucial to fully understand the fundamental properties of the standard and its implications on the safety aspects of the network traffic. In this letter, we identify critical aspects and limitations of the standard. We demonstrate the risks of inadequate configurations, discuss their ramifications. Finally, we provide an intuition and initial steps toward deriving the formal worst-case timing analysis of the standard, which is a key requirement for its safe and efficient implementation in the aforementioned real-time domains.

中文翻译：

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IEEE 802.1CB-2017 的挑战和局限

对于许多基于以太网的实时系统，例如来自汽车、航空电子和工业自动化领域的系统，容错已成为实现故障安全或故障操作行为的基本要求。因此，IEEE 802.1CB-2017 标准发布了。它是目前唯一可用的时间敏感网络组标准，可以防止传输错误。它通过预防性复制帧并通过不同路径将冗余副本传输到目的地来解决这些故障。然而，与其明显的优势相比，该标准也存在一些缺陷：最值得注意的是，它缺乏针对不适当配置的保护机制，这不仅会使预期的可靠性增加无效，甚至会主动危害网络的安全。由于缺乏替代机制，充分了解标准的基本属性及其对网络流量安全方面的影响至关重要。在这封信中，我们确定了标准的关键方面和局限性。我们展示了配置不当的风险，讨论了它们的后果。最后，我们提供了推导出标准的正式最坏情况时序分析的直觉和初始步骤，这是其在上述实时域中安全有效实施的关键要求。我们展示了配置不当的风险，讨论了它们的后果。最后，我们提供了推导出标准的正式最坏情况时序分析的直觉和初始步骤，这是其在上述实时域中安全有效实施的关键要求。我们展示了配置不当的风险，讨论了它们的后果。最后，我们提供了推导出标准的正式最坏情况时序分析的直觉和初始步骤，这是其在上述实时域中安全有效实施的关键要求。