Hierarchical traffic shaping and frame packing to reduce bandwidth utilization in the AFDX

The increasing complexity and heterogeneity of avionic networks make resource savings a challenging task to guarantee easy incremental design during the lifetime of an aircraft. In this paper, we focus on the optimization of interconnection devices for multi-cluster avionic networks, called Remote Data Concentrators (RDC), and especially for the CAN-AFDX network. The design of this optimized RDC device consists of implementing frame packing strategies to manage upstream (sensors) flows to improve bandwidth utilization in the AFDX; and a Hierarchical Traffic Shaping (HTS) algorithm to control downstream (actuators) flows to guarantee bandwidth isolation on CAN. Schedulability analysis integrating the effects of these new mechanisms is detailed and validated. Furthermore, a heuristic approach to tune the HTS parameters within the RDC device is proposed to reduce as much as possible bandwidth utilization in the AFDX, while ensuring flow schedulability. Our performance analysis conducted on a realistic avionic case study demonstrates the efficiency of the optimized RDC device to reduce bandwidth utilization in the AFDX, compared to the basic device currently implemented in avionics.