EXAMENSARBETE INOM TEKNIK, GRUNDNIVÅ, 15 HP STOCKHOLM, SVERIGE 2020 An Evaluation of Ethernet as Data Transport System in Avionics RICKARD DOVERFELT KTH SKOLAN FÖR ELEKTROTEKNIK OCH DATAVETENSKAP An Evaluation of Ethernet as Data Transport System in Avionics RICKARD DOVERFELT Degree Programme in Information and Communication Technology Date: 7th October 2020 Supervisor: Markus Hidell Examiner: Peter Sjödin School of Electrical Engineering and Computer Science Host company: ÅF Digital Solutions AB Swedish title: En utvärdering av Ethernet som datatransportssystem inom avionik An Evaluation of Ethernet as Data Transport System in Avionics / En utvärdering av Ethernet som datatransportssystem inom avionik © 2020 Rickard Doverfelt Abstract | i Abstract ÅF Digital Solutions AB are looking to replace their current legacy system for audio transmissions within aircrafts with a new system based on Ethernet. They also want the system to be as closely matching the current Audio Integration System as possible as well as preferably using commercial off the shelf components. The issue evaluated in this thesis is whether it is feasible to port the legacy protocol over to an Ethernet based solution with as few modifications as possible, what performance requirements are present on the Ethernet solution as well as what remaining capacity is available in the network. Furthermore is ÅF Digital Solutions AB interested in what avionics related Ethernet based protocols and standards are already present on the market. The work is conducted in two tracks - one track of experimental measurements and statistical analysis of the latency present in the proposed solutions and one track with a survey regarding the integration of the present Audio Integration System protocol into the propesed Ethernet based solutions. The study finds two standards present on the market: Avionics Full-Duplex Ethernet (AFDX) and Time-Triggered Ethernet (TTEthernet). Two prototype implementations are built, one implementing AFDX and one custom built upon Ethernet and UDP. The latency of these are measured and found to be largely similar at ideal conditions. Ethernet is found to be more flexible, whilst AFDX allow for interoperation with other manufacturers and TTEthernet facilitates strict timing requirements at the cost of specialised hardware. The bandwidth utilisation of AFDX at ideal conditions is found to be 0.980% per stream and for the Ethernet solution 0.979% per stream. It is proposed that ÅF Digital Solutions AB pursue a custom Ethernet based solution unless they require interoperability on the same network with other manufacturers as a custom solution with full control over the network allows the largest flexibility in regards to timings and load. If interoperability is required is AFDX proposed instead as it is a standardised protocol and without the, for ÅF Digital Solutions AB, unnecessary overhead of TTEthernet. Keywords AFDX, Avionics, Bandwidth utilisation, Ethernet, Latency, Legacy systems ii | Abstract Sammanfattning | iii Sammanfattning Åf Digital Solutions AB vill undersöka möjligheterna att byta sitt nuvarande legacysystem för kommunikation inom flygplan till ett Ethernet-baserat system. Detta på ett sätt som håller implementationen så nära deras nuvarande Audio Integration System som möjligt. Problemet som undersöks är huruvida det är rimligt att flytta legacyprotokollet till Ethernet med så lite modifikationer som möjligt. Utöver detta vill ÅF Digital Solutions AB veta prestandakraven som blir på en Ethernet-lösning samt hur mycket resterande kapacitet som eventuellt finns kvar för framtida användning. Vidare vill de veta vilka standarder som redan finns på marknaden. Arbetet genomförs genom två spår - ett med experimentella mätningar och statistisk analys och en med ett case-study av integrationen av Audio Integration System och Ethernet. Undersökningen finner två standarder på marknaden relaterat till avionik; Avionics Full-Duplex Ethernet (AFDX) samt Time-Triggered Ethernet (TTEthernet). Två prototyper byggs, en baserad på AFDX och en baserad på UDP och Ethernet. Latencyn för dessa två mäts och finns vara snarlika vid deras respektive ideala scenarion. Ethernet finns vara mer flexibelt, AFDX mer interoperabel och TTEthernet mer lämplig vid strikta tidskrav. Bandbreddsutnyttjandet för AFDX finns vara 0.980% vid ideala förhållanden och 0.979% för Ethernet vid ideala förhållanden. Det rekommenderas att ÅF Digital Solutions använder sig av en egenutformad Ethernetbaserad lösning om de inte har krav på interoperabilitet ty det ger mer flexibilietet gällande tidskrav, protokoll och dataflödet. Nyckelord AFDX, Avionik, Bandbreddsutyttjande, Ethernet, Latency, Legacysystem iv | Sammanfattning Acknowledgments | v Acknowledgments I would like to thank Alexander Pukhanov at AFRY for his supervision of this thesis work and his willingness to help and find information on how the present optical system works. I would also like to thank Kenneth Fornstål for providing ideas on how to measure the latency of the present optical system and help performing said measurements. AFRY should also have a thank you for letting me do this thesis and providing the documents, standards, materials and equipment that I needed. Stockholm, October 2020 Rickard Doverfelt vi | Acknowledgments CONTENTS | vii Contents 1 Introduction1 1.1 Background...........................1 1.2 Problem.............................2 1.2.1 Original problem and definition............2 1.2.2 Scientific and engineering issues............2 1.3 Purpose.............................3 1.4 Goals..............................3 1.5 Work Structure.........................4 1.6 Delimitations..........................4 1.7 Structure of the Thesis.....................5 2 Background7 2.1 Avionics and Aircraft Audio System and Equipment......7 2.1.1 Avionics and Aerospace Industry...........7 2.1.2 European Technical Standard Order..........8 2.1.3 Aircraft Audio System and Equipment.........8 2.2 IEEE 802.3 Ethernet......................9 2.2.1 Network Layer..................... 11 2.2.2 Transport Layer..................... 12 2.3 Current System at ÅFDS.................... 12 2.4 Related Work.......................... 13 2.4.1 Airbus’ Ethernet Implementation AFDX........ 14 2.4.2 Time-Triggered Ethernet................ 15 2.5 Summary............................ 15 3 Method 17 3.1 Survey Process......................... 17 3.2 Prototype Development..................... 18 viii | Contents 3.3 Experimental Design and Planned Measurements..................... 19 3.3.1 Test Environment.................... 19 3.3.2 Hardware/Software................... 21 4 Prototype Design 23 4.1 Study of present solutions.................... 23 4.1.1 ARINC 664p7..................... 23 4.1.2 AS6802......................... 23 4.2 System Design......................... 24 4.2.1 AFDX Packet Structure................. 25 4.2.2 Ethernet Packet Structure................ 26 4.3 Implementation......................... 27 4.3.1 Addressing Scheme................... 27 4.3.2 Hardware........................ 28 4.3.3 Software........................ 29 5 Results and Analysis 33 5.1 The Ethernet System...................... 33 5.2 The AFDX Solution....................... 36 5.3 AIS............................... 40 5.4 Literature............................ 40 5.4.1 Functional Aspects................... 41 5.5 Bandwidth utilisation...................... 42 6 Discussion 45 6.1 AFDX and Ethernet....................... 46 6.2 Stability of the AIS....................... 47 6.3 TTEthernet........................... 47 6.4 Comparison of Systems..................... 48 6.5 Bandwidth Utilisation...................... 49 7 Conclusions and Future work 51 7.1 Conclusions........................... 51 7.2 Limitations........................... 52 7.3 Future work........................... 53 7.4 Reflections........................... 53 References 55 LIST OF FIGURES | ix List of Figures 2.1 Structure of MAC packet.................... 10 2.2 Structure of IPv4 header [9].................. 11 2.3 Structure of UDP header [12].................. 12 2.4 Structure of a packet in AIS................... 13 3.1 Survey Process......................... 18 3.2 Test setup, calibration...................... 19 3.3 Test setup, latency........................ 19 3.4 Visualisation of timestamp placement during send....... 20 3.5 Visualisation of timestamp placement during receive..... 20 3.6 Structure of a log entry for both solutions........... 21 3.7 Test setup, latency (AIS).................... 22 4.1 Layout without central hub................... 24 4.2 Layout with central hub..................... 25 4.3 Structure of an AFDX packet, based on [13].......... 26 4.4 Structure of AFDX Payload for AFDS’s data streams..... 27 4.5 Structure of Multicast IP for AFDX............... 28 4.6 Structure of Unicast IP for AFDX................ 28 4.7 Structure of Multicast MAC for AFDX............. 28 4.8 Structure of Source MAC for AFDX.............. 28 4.9 ÅFDS payload as struct..................... 29 5.1 Ethernet Calibration....................... 33 5.2 Ethernet Latency........................ 34 5.3 Ethernet Latency (Compensated)................ 34 5.4 Ethernet Latency Distribution................. 35 5.5 AFDX Calibration........................ 36 5.6 AFDX Latency (Crowded)................... 37 5.7 AFDX Latency (Compensated, Crowded)........... 37 x | LIST OF FIGURES 5.8 AFDX Latency Distribution (Crowded)............ 38 5.9 AFDX Latency (Ideal)..................... 39 5.10 AFDX Latency (Compensated,