Study On Multi-Link Failure Protection Strategy Of Optical Transport Network For High-spreed Railway

The high-speed railway optical transport network is the core of the high-speed railway ground infrastructure,carrying the key information related to train operation,ensuring the safety and reliability of train operation.With the increasing variety of high-speed railway optical transport network bearer services,the requirements for network reliability and real-time performance of different service types are constantly improving.Ensuring the safe operation of the high-speed railway optical transport network is the research focus of the railway communication network protection and recovery technology.This paper mainly studies the multi-link failure protection strategy of high-speed railway optical transport network.The research focuses on optical transport network protection and recovery technologies based on service flow class grading,which satisfies the reliability and real-time requirements of different types of services and improves the survivability of the network under the multi-link failure scenario.1.This paper proposes a P-cycle optimization construction heuristic algorithm C-Grow(Combination-Grow).The algorithm fully considers the actual cost and maximum protection ability of constructing P-cycle when calculating P-cycle protection performance.By introducing P-cycle evaluation index protection cost efficiency K,the former U intermediate circle is filtered.The circle cross combination method is used and the method strictly limits the number of P-cycles constructed and improves the actual performance of the P-cycle.The simulation results in three network topologies of COST239,SmallNet and NSFNet show that under the same link weight,the C-Grow algorithm outperforms the existing P-cycle construction algorithm Grow in terms of P-cycle number,average protection cost efficiency and average prior efficiency.2.This paper proposes a Service Classification-Failure Protection Recovery Algorithm(SC-FPRA)based on the classification of service flow.According to the service flow carried by the high-speed railway optical transport network,the service flow is classified according to the requirements of network reliability and real-time performance.In the P-cycle construction and configuration process,the algorithm preferentially configures the P-cycle for the link carrying the high-level service flow and introduces the high-level protection efficiency(HGPE)of the P-cycle evaluation index.The algorithm comprehensively considers the protection capability of the P-cycle for carrying high-level service capacity links and the protection capacity of the actual working capacity.When a single link failure occurs in the network,the failure link protection is implemented by using the pre-configured P-cycle in the network.When a dual-link failure occurs on the network,the pre-configured P-cycle in the network maximizes the protection of links carrying high-level service flow in the network.When the pre-configured P-cycle fails to meet the requirements,the method of utilizing link dynamic route recovery in the network finds a recovery path for the failure link.The simulation results show that compared with the CIDA(Capacitated Iterative Design Algorithm)algorithm,the algorithm SC-FPRA achieves better protection for links carrying high-level traffic flows at the cost of consuming a small amount of idle resources and increasing a small amount of algorithm time.Under the dual link failure scenario,SC-FPRA algorithm can achieve nearly 100%protection and recovery effect of the failure link,and has better protection and recovery performance.