Implementation and Validation of the Fundamental Mechanisms of the Flexible Time-Triggered Communication Paradigm for Ethernet-based Highly-Reliable Systems

Abstract

[eng] Ethernet is nowadays the most widespread communication standard for local networks in the domestic and office environment. Its main advantages are: high bandwidth, low price of components and compatibility with other communication standards. For that reason it is considered interesting to use Ethernet in industrial systems. Industrial systems have additional requirements not present in domestic or office environments. Specifically, they have real-time and dependability (reliability, availability and/or security) requirements. In addition, it is not uncommon that this kind of systems are deployed in dynamic environments, that is, environments where the operational conditions can change unexpectedly. Unfortunately, Ethernet by itself does not provide the necessary services to fulfil all these requirements. To overcome this limitation, the Dynamic Fault Tolerance for Flexible Time Triggered (FTT) (Dynamic Fault Tolerance for Flexible Time Triggered (DFT4FTT)) project aims at providing a complete infrastructure to support applications with real-time, reliability and adaptivity requirements. Specifically, the Dynamic Fault Tolerance for Flexible Time Triggered (DFT4FTT) architecture is based on the Flexible Time-triggered communication paradigm. Flexible Time Triggered (FTT) makes it possible to exchange periodic and aperiodic traffic with different criticality levels in a real-time manner. Moreover, it allows to modify the real-time attributes of the traffic dynamically. The Dynamic Fault Tolerance for Flexible Time Triggered (DFT4FTT) architecture modifies Flexible Time Triggered (FTT) to achieve high reliability by means of fault-tolerance mechanisms. This is done by replicating the the network and the nodes. Themain problem when implementing the Dynamic Fault Tolerance for Flexible Time Triggered (DFT4FTT) architecture is that Flexible Time Triggered (FTT) was not designed having fault tolerance in mind. Moreover, fault tolerance mechanisms are typically not orthogonal to the operation of the system. Consequently, it is very costly to extend the Flexible Time Triggered (FTT) software to include these mechanisms. In this regard, it was decided to implement Flexible Time Triggered (FTT) from a new design which removes unnecessary and non-reliable functionalities, and makes roomfor the new fault tolerance mechanisms. This project represents the first step towards a new implementation of Flexible Time Triggered (FTT) for highly-reliable systems. Specifically, this project consisted in the implementation and validation of a basic Flexible Time Triggered (FTT) network which can then be easily extended to implement the necessary fault tolerancemechanisms.