Three-layer Switching Technology Research For Train Real-time Ethernet

In recent years,with the continuous development of high speed and intelligent on trains,dramatic increase train communication network transmission of information,the transmission speed of train communication network and real-time requirements more stringent,traditional stranded wire train bus WTB and MVB allows MVB is difficult to meet the requirements,and the train based on real-time Ethernet Backbone Network and Ethernet Consist Network application more widely,and train network ETB with ECN information interaction between two network is the basis of train communication network,therefore,to carry out the ETB between ECN and three-layer switching technology research has important significance.In this paper,the design scheme of two-layer hard switching and network layer soft switching is adopted,and the principle prototype of three-layer ETB and ECN switching equipment is developed.The hardware and software design and functional test are completed,and the experimental application of train ground debugging is carried out.Two-layer hard switching based on Marvell 88E6095 implementation,support VLAN virtual LAN partition and port mirroring;Based on STM32F407 controller,network layer soft exchange carries out the design,transplanted the ?Cos-II real-time operating system,deeply modified the LWIP protocol stack,established the dynamic routing table,and realized the routing and forwarding of IP packets by using the software.As the master control chip,STM32F407 connects to Marvell 88E6095 through MII interface to realize its chip management.Meanwhile,based on the real-time operating system,STM32F407 can complete multiple real-time tasks such as routing and forwarding,network card data monitoring,system running state monitoring,and switch command configuration.This paper studies the Train Topology Discovery Protocol and gives the preliminary software design scheme.Finally,the second layer exchange,third layer exchange,switch cascade,passive bypass and other functions of ETB three-layer switch were tested.Meanwhile,the RCF2544 test,high and low temperature test and EMC test of the switch were completed,and the topic was summarized and prospected.