Realization of virtual networks in the DECOS integrated architecture

Due to the better utilization of computational and communication resources and the improved coordination of application subsystems, designers of large distributed embedded systems (e.g., in the automotive domain) are eager to replace existing federated architectures with integrated ones. This paper focuses on the communication infrastructure of the DECOS integrated system architecture, which realizes for each application subsystem a so-called virtual network as an overlay network on top of a time-triggered communication protocol. Since all virtual networks share a single physical network, virtual networks promise massive cost savings through the reduction of physical networks and reliability improvements with respect to wiring and connectors. Furthermore, virtual networks support application subsystems that range from ultra-dependable control applications (e.g., an X-by-wire system) to non safety-critical applications such as comfort systems. For this reason, two classes (event-triggered and time-triggered) of virtual networks are realized. Encapsulation mechanisms ensure that the temporal properties of each virtual network are known a priori and independent from the communication activities in other virtual networks. In order to ensure that the virtual network abstractions hold also in the case of software faults, each application subsystem possesses a dedicated virtual network with statically assigned resources at the underlying time-triggered communication service