Realization of virtual networks in the DECOS integrated architecture

Due to the better utilization of computational and communication resources and the improved coordina-tion of application subsystems, designers of large dis-tributed embedded systems (e.g., in the automotive do-main) are eager to replace existing federated architec-tures 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 net-work on top of a time-triggered communication proto-col. Since all virtual networks share a single physical network, virtual networks promise massive cost savings through the reduction of physical networks and reliabil-ity improvements with respect to wiring and connectors. Furthermore, virtual networks support application sub-systems that range from ultra-dependable control ap-plications (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 mecha-nisms ensure that the temporal properties of each vir-tual network are known a priori and independent from the communication activities in other virtual networks. In order to ensure that the virtual network abstrac-tions hold also in the case of software faults, each ap-plication subsystem possesses a dedicated virtual net-work with statically assigned resources at the underly-ing time-triggered communication service.