Research On Real-time Ethernet Safety Communication Protocol Based On TRDP

With the vigorous development of China’s rail transportation industry,the amount of data transmitted through train communication networks is increasing.Compared to traditional train communication buses,Ethernet’s outstanding advantage of high transmission rate has become the choice for more and more train communication networks.For the application of Ethernet on trains,IEC 61375 specifies detailed technical details and higher requirements for the safety of Ethernet communication.The current safety integrity level(SIL)of existing real-time Ethernet communication on trains is generally SIL2 level,which cannot meet the higher safety requirements of the next generation train communication networks.This article studies the functional safety of the Train Real-time Data Protocol(TRDP)for real-time train data,improves the functional safety of Safe Data Transmission version 2(SDTv2)protocol by analyzing the shortcomings of the safety data transmission protocol defined in IEC 61375-2-3,and theoretically calculates that the improved SDTv4 protocol can achieve SIL4 level of functional safety.The main work of this paper is as follows:(1)Improvement measures were proposed specifically by analyzing the deficiencies of the SDTv2 protocol.Basic message threats faced by the train communication network are studied,including message damage,message repetition,message disorder,message loss,and message delay.The architecture and functional safety measures of the SDTv2 protocol are studied in detail.At the same time,based on actual research,the deficiencies of the SDTv2 protocol are pointed out,and improvement measures targeting the SDTv2 protocol are proposed.(2)Implemented injection of nine different basic message threats.For the nine basic message threats defined in IEC61375-2-3,different message threat injections were implemented through software programs.At the same time,Wireshark was used to capture packets to verify the correctness of the designed nine different basic message threat measures.(3)Safety measures for SDTv4 protocol against nine types of basic message threats were designed and implemented.In response to the shortcomings of the SDTv2 protocol when applied to the TRDP protocol defined by IEC61375-2-3,the design of the SDTv4 protocol includes different safety measures,such as Safe Sequ Count,Safety Code,destination time detection,and channel detection.Through program coding,different message threats among the nine basic ones are detected,and upon detecting message threats,corresponding error messages are safely discarded.(4)The accuracy of the SDTv4 safety communication protocol is experimentally verified.In the laboratory,two hosts are used to simulate the safety equipment of train communication,and the verification of the SDTv4 safety communication protocol is achieved through a switch connection.After injecting threatening messages,the safe data receiver detects and alerts the threatening messages,and discards incorrect messages through various sty measures designed in the SDTv4 protocol.Finally,through theoretical calculations,it is proved that the improved SDTv4 protocol has a lower residual error rate than SDTv2 and a higher safety integrity level than SIL2.This article can provide reference significance for the research of functional safety of the next generation of train communication networks.