A software-based redundancy concept for building automation networks

Reliability in automation networks is an important topic. Thus, redundant communication is fundamental in this context. In contrast to other automation domains, building automation networks facilitate Ethernet and IP communication and require reliable and predictable communication that are ideally based on standard network technologies. Since automation components are often based on commonly used operating systems, software-based solutions come into play. However, pure software-based solutions are inefficient and often infeasible due to limited processing resources. Thus, a hybrid redundancy concept is proposed that facilitates standard hardware components in combination with lightweight software modules. This paper presents a new redundancy mechanism for Ethernet networks based on a ring topology. This approach makes use of VLAN-capable Ethernet switches in combination with software modules for controlling the network traffic. Thereby, VLANs are used to provide physical redundancy by preventing from Ethernet loops. The proposed concept can therefore be used on different platforms and provides a transparent and reliable communication channel for automation applications. The concept is theoretically analyzed. Finally, a proof-of-concept shows the feasibility.