Worst-Case Timing Analysis of AFDX Networks With Multiple TSN/BLS Shapers

Abstract

This paper addresses the problem of worst-case timing analysis of extended Avionics Full Duplex Switched Ethernet (AFDX) networks, incorporating Time-Sensitive Networking (TSN) shapers called Burst Limiting Shapers (BLS), to enable the interconnection of different avionics domains with mixed-criticality levels, e.g., current AFDX traffic, Flight Control and In-Flight Entertainment. Conducting such an analysis is a challenging issue when considering multiple BLS-shaped traffic classes, due to the sophisticated inter-dependencies between the different shapers sharing the same output capacity. We tackle this problem through extending the applicability domain of our previous work for computing maximum delay bounds using Network Calculus and considering only one BLS class, called Continuous Credit-based Approach (CCbA), to handle multiple TSN/BLS classes. We provide further insights into the sensitivity and tightness issues of worst-case delay bounds yielded with the Generalized CCbA (GCCbA). Our assessments show that the tightness ratio is up to 85%, with reference to Achievable Worst-Case delays. We also show the improvements against recent state-of-the-art approaches in terms of tightness and complexity, where the computation time is up to 10 5 faster. Finally, we evaluate the efficiency of GCCbA for realistic avionics case studies, e.g., adding A350 flight control traffic to the AFDX. Results show the good applicability of GCCbA and confirm the efficiency of the extended AFDX, which decreases the delay bounds of the existing AFDX traffic by up to 49.9%, in comparison with the current AFDX standard.

Network Calculus-Based Latency for Time-Triggered Traffic under Flexible Window-Overlapping Scheduling (FWOS) in a Time-Sensitive Network (TSN)

“…The IEEE TSN standards define two different shaping approaches, namely time-aware shaping (TAS) in IEEE 802.1Qbv [5] for scheduled streams and credit-based shaping (CBS) for unscheduled flows in IEEE 802.1Qav [4]. Although other shapers can implement the traffic schedule in TT-Ethernet, such as the burst-limiting shaper (BLS) [14,15] and the peristaltic shaper (PS) [16], the TSN task group has standardized the TAS to shape TT streams. The TAS mechanism is more applicable than the others to ensure a bounded latency for control traffic [17].…”

Priority Re-assignment for Improving Schedulability and Mixed-Criticality of ARINC 664

“…Network calculus that lies in a theoretical background of Min-plus algebra allows us to calculate the upper bound delay [9]. Therefore, it is widely used to analyze the worst-case delay bounds for deterministic networks including ARINC 664 or IEEE TSN [10] [11]. In the following two subsections, we present the worst-case delay analysis for the FPA, DPA, BLS-FPA, and BLS-DPA methods.…”

“…β bls LP (t) = R • t − Υ bls HP − max i∈(HP,LP,BE) s i + , (10) where denotes the min-plus deconvolution operator and Υ bls HP represents the maximum service curve offered by the BLS. It becomes Υ bls HP = R • t when there is no backlogged LP traffic, otherwise:…”

“…1. The same experiment parameters in [10] are used in this study. The maximum frame size (MFS) and the bandwidth allocation gap (BAG) are set to 64 bytes and 2 ms for SCT and RC flows, respectively, while MFS for BE is 1024 bytes and BAG is 8 ms.…”

“…Without loss of generality, the delay requirements for both HP and LP traffic classes are set to 2 ms. The L M , L R , and BW parameters required for the BLS-FPA and BLS-DPA experiments are set to 22118, 0 and 0.46, respectively, as in [10]. The BW parameter of 0.46 means that the bandwidth of the HP class is set to the 46% of the total outgoing capacity.…”