End To End Delay Analysis In AFDX Network

Due to the growing complexity of avionics systems and the increasing amount of communication requirements, Avionics Full Duplex Switch Ethernet (AFDX) has been adopted as the aircraft backbone data network for the next generation aircraft databus. The AFDX protocol standard, defined as the specification ARINC 664 Part 7 upon the full duplex Switch Ethernet technology, takes the advantages of commercial off-the-shelf (COTS) switch Ethernet network in low cost and sufficient bandwidth (100Mbps). AFDX is considered as the next generation of avionic databus because of its numerous advantages in comparison with its antecessors such as ARINC429 with limited bandwidth of 100kbps or 12.5kbps and MIL-STD-1553 bus.The accurate transmission performance analysis and end-to-end (e2e) delay evaluation are primary concerns for avionic data bus. However, the key challenge is that the data transmission in AFDX network has large latency and jitter due to the transmission resource competition in switch schemes. In this paper, we focus on how to calculate the end to end data transmission delay effectively in AFDX network using network calculus theory and how that bounded delay satisfies the deterministic real-time guarantees and requirements.The main work and research results are summarized as follows:(1) Model the AFDX network entity using basic network elements (scheduler, queues, regulator, etc.). End system is composed of virtual link queues, regulator and scheduler. AFDX switch consists of packetizers, forward processor and scheduler.(2) Modify the traditional representation of data flows and propose a more accurate and precise mode for the AFDX virtual link. A tighter e2e latency bound is obtained by comparison of the original upper bound and our new upper bound.(3) Employ a compositional scheduling algorithm-Static Priority combined Weighted Round Robin (SP-WRR) to the queuing module of AFDX switch. Analyze the corresponding e2e delay for the avionics data flows and multimedia flows which have different priorities.(4) TrueTime toolbox is used to construct our network simulation platform which consists of several switches and end systems in order to verify our proposed end to end delay theory in AFDX network.