Half&Half: Intra-Flow Load Balancing and High Availability for Edge Cloud-enabled Manufacturing.

The virtualization of real-time critical workloads on edge clouds is rapidly gaining attention, placing a greater emphasis on communication between the physical and virtualized worlds. However, traditional IP-based networks lack the mechanisms to provide sufficient failover time for a variety of time-critical applications found in manufacturing, such as virtualized Programmable Logic Controllers (vPLCs). So far, only packet duplication mechanisms have been considered to meet the stringent High Availability (HA) requirements of real-time applications. In this work we propose the novel approach half&half which is characterized by sending packets alternately over two disjoint paths without duplicating them. The validation conducted confirms the applicability of half&half for the two most widely used Industrial Ethernet protocols, PROFINET and EtherNet/IP. The approach offers a comparable level of resilience to packet duplication, while requiring the same throughput as single-path communication and eliminating complexity on the receiver side, facilitating edge-cloud enabled manufacturing.