Applacation Study On Virtual Link Layer In Protocol Stack Of AFDX End System

With the complexity of avionics systems increasing, it also brings forth higherrequirements for the width of avionics data bus. The successful trial of usingAvionics Full Duplex Switched Ethernet （AFDX） has escalated the avionicssystem entering into a new highly integrated era. End system performed as aimportant part in AFDX network, however AFDX protocol stack plays a importantrole in AFDX end system design. UDP、IP layer of AFDX protocol stack functionsthe same as common Ethernet. To eliminate the uncertainty of Ethernet andguarantee the safety and reliable of air communication, new functions are addedinto virtual link layer, so it’s the key point of end system design. At present, ourcountry is in the critical period of vigorously developing large and medium-sizedaircrafts, thus it will play a positive role and have a significance meaning for us todevelop large aircrafts with independent intellectual property rights once we beginto research and finally use the AFDX end system virtual link layer.First, traditional avionics data bus, such as ARINC429and1553B and newavionics data bus AFDX’s development status and advantages and disadvantagesare analyzed. Therefore the AFDX network’s great superiority and the necessity tostudy and develop AFDX network are demonstrated.Second, AFDX end system virtual layer protocol is comprehensive analyzed onthe basic of a brief introduction of the importance of AFDX end system virtual linkin the AFDX network. Then the overall structure of AFDX end system virtual link isput forward. And MAC module and receiver module and transmitter module areincluded in the AFDX virtual layer.Third, avionic Ethernet MAC module based on FPGA is detailed designed,then transmitter and reciver function of MAC module is tested successfully. AFDXend system virtual link layer’s special receiver module and transmitter modulebased on FPGA is designed and simulated with MAC module. In particularsimulation analysis aims at redundancy frame processing case in the AFDX protocol,and the results show that the redundancy management fully meets the requirements.Last, AFDX end system communication test is performed on the basic of allthe successful simulation. First two self-designed AFDX communications boardcommunicate successfully on the basic of aviation electronic systems to verify thebasis of the normal communication function of the AFDX end system. To verify theapplicability of the AFDX board, a communication between GE’s AFDX boardand our AFDX board is performed. And the two sides’ communication normal, this proved our AFDX board has a good performance. After this, a standard AFDXcommunication network is created and many AFDX boards are connected withAFDX switch. Many AFDX boards communicate with each other successfully withthe help of full duplex AFDX switch.