Research On Link Failure Protection And Recovery Mechanism Of High-speed Railway Optical Transport Network

The high-speed railway optical transport network undertakes the work of train operation control,dispatching command,state monitoring and fault emergency treatment,which ensures the safety and reliability of train operation.With the increasing variety and quantity of high-speed railway optical transport network carrying services,the requirements of network reliability and real-time are increasing.The protection scheme of optical transport network has become the focus of the research on the protection and recovery technology of railway communication network.This paper mainly studies the link failure protection technology of high-speed railway optical transport network.The research focuses on the division of area and the spare capacity allocation network protection scheme,which meet the reliability and real-time requirements of the network in different services scenarios and topologies,and improve the network survivability.(1)In view of the fact that the current P-Cycle protection algorithm does not consider the unprotected working capacity distribution on the link,which results in the different quality and performance of the constructed P-Cycle,this paper proposes an Extended Edge Restriction based P-Cycle Construction Algorithm(ERPA).The algorithm fully considers the distribution of unprotected working capacity on the link when expanding the basic cycle,and filters the expanding cycle by introducing the expansion parameter P,which is the ratio of variance to mean.The algorithm effectively limits the number of protection cycles needed and improves the performance of the P-Cycle.The simulation results of the algorithm in cost239 network topology show that the ERPA algorithm is superior to the existing POCA(P-Cycle optimization configuration heuristic algorithm)algorithm in running time,actual protection efficiency,total redundancy and average protection efficiency under the same protection capacity.(2)Aiming at the problem of time delay caused by cross area protection of high-speed railway optical transport network,and the problem of time delay and loss caused by too long P-Cycle in network protection.This paper proposes a Division of Area Extended Edge Restriction based P-Cycle Construction Algorithm(DA-ERPA).Firstly,the ILP model is established to divide the whole optical transport network topology into several areas.Then,P-Cycle protection strategy is applied to inter arealink and intra area link respectively.The DA-ERPA algorithm and ERPA algorithm are simulated in cost239.The running time,average length of P-Cycle and actual protection efficiency of the algorithm are selected to verify.It is proved that the performance of DA-ERPA algorithm is better when protecting the same service request.(3)To solve the problem of limited link capacity in optical transport network,this paper proposes a Space Capacity Allocation based P-Cycle Construction Algorithm(SC-APCA),and its advantages are verified by comparing with the traditional Capacitated Iterative Design Algorithm(CIDA).SC-APCA algorithm is based on a certain total capacity of each link.In the selection of P-Cycle extension edge,the distribution of idle capacity on the link is fully considered,and the important reference standard K is introduced,which represents the mean value of idle capacity over the extension circle.By choosing the link with larger mean free capacity to construct P-Cycle,the network reliability is improved under the condition of limited free capacity.The simulation results of the algorithm in cost239 network topology show that SC-APCA algorithm can improve network reliability and reduce network management pressure.