Performance Evaluation on Packet Transmission for AFDX Networks Using Optimized Forward End-to-End Delay Analysis
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ORIGINAL PAPER
Performance Evaluation on Packet Transmission for AFDX Networks Using Optimized Forward End-to-End Delay Analysis Qingfei Xu1,2 · Xinyu Yang1 Received: 20 August 2019 / Revised: 24 February 2020 / Accepted: 25 February 2020 © The Korean Society for Aeronautical & Space Sciences 2020
Abstract AFDX (Avionics Full Duplex switched Ethernet) standardized as ARINC 664 is chosen as the backbone network for distributed real-time avionics systems as it offers high throughput and does not require global clock synchronization. A deterministic upper bound of the end-to-end transmission delays for packets of each flow should be guaranteed to ensure the network performance. In this paper, we focus on the forward end-to-end delay analysis (FA). This approach iteratively estimates the maximum backlog (amount of the pending packets) in the switch output port along the transmission path so that the worst-case end-to-end transmission delay can be computed and the network performance can be evaluated. Recent research demonstrates this approach is pessimistic (overestimated). This paper presents an optimization which considers the serialization effect of packets transmitted through the same physical link. We provide a comparative analysis on both sample network configurations and real industrial systems. The experiments show that by considering the serialization effect the forward end-to-end delay analysis can remove the pessimism in the analysis of end-to-end transmission delay. The evaluation of network performance can be improved. Then a discussion on the potential optimism (underestimation) is presented. Keywords Performance evaluation · Worst-case delay · Backlog · Real-time transmission · AFDX · Serialization
List of Symbols F max Ci Ti Pi L Smaxih Sminih G hx
B
Maximum packet length in an AFDX network Maximum transmission time of a packet generated by flow vi Minimum time interval of two consecutive packets generated by flow vi Transmission path of flow vi Switching fabric delay, upper-bounded to 16 µs Maximum end-to-end transmission delay of packet mi from its source node to node h Minimum end-to-end transmission delay of packet mi from its source node to node h Maximum servicing rate of a node in AFDX network, usually 100 Mb/s A node which has an input physical link with number x
Qingfei Xu [email protected]
1
School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an, China
2
Civil Aviation Division, Shanghai Aviation Electric Co. LTD, Shanghai, China
Ri
Worst-case end-to-end transmission delay of a packet generated by flow vi Rih Maximum transversal delay from the generation time of packet mi at its source node to its departure time at node h S Node set of an AFDX network G Flow set transmitted over an AFDX network Flow set transmitted though node h Gh Worst-case arrival jitter of flow vj at node h J jh Bh The upper bound of the test time interval t h The input physical link to node h with number x IPx The delay caused by the packets from physical link Wxh (t) IPhx durin
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