Research On Fault Generation And Survivability In The Railway Optical Transport Network

With the application of intelligent optical network in railway and the emergence of large granular service in railway transmission network,OTN gradually develops to be the main technology adopted for the transmission network as a typical representative of the next generation optical transmission network.As the main bearing network of railway data information,railway OTN carries all kinds of information such as train operation,dispatching,mobile communication,video monitoring and so on.OTN network has already stepped towards 40G and 100G from 10G.In such super-speed,ultra-large capacity,multi-service optical transport network,the network breakdown will bring extremely potential safety hazard to the railway network.In order to prevent the huge impact and loss caused by the network failure to the railway service,the network survivability has become the key performance index in the planning and design of the railway transmission network.This paper mainly focus on quantitative analyzing the survivability of OTN based on the OTN protection technology and the whole network service reliability constraint based on Routing and Wavelength Assignment(RWA)algorithm.According to the testing data,the performance of the algorithm is compared and analyzed.The main work and specific research results are shown as follows:1.The theory is verified and analyzed by establishing different OTN protection test environment and taking advantage of actually obtained test data by using the relevant test instrument,the fault processing procedure of OTN various protection technology,including the detection of fault,overhead processing,fault notification and protection switching process.Through the survivability evaluation index,the network performance of different the protection technology is analyzed and compared respectively and technical selection scheme aiming at different realistic network environment is obtained.2.The problem of network survivability design in static traffic of railway OTN is solved.The RWA algorithm of service reliability constraint based on single-link failure is proposed by decomposing the RWA problem into the sub-problem of routing and sub-problem of wavelength assignment.In the routing selecting,the influence of single-link failure on the whole network service is described from the perspective of service reliability requirements.The routing scheme with optimal reliability is allocated to the optical connection request to reduce the failure impact.In the wavelength assignment,the objective function and the constraint condition are set by establishing the dedicated path protection model with ILP.The performance of the algorithm is verified by simulating the network topology with different scale.The simulation results show that the algorithm can greatly improve the reliability of the whole network service compared with the traditional shortest path(SP)algorithm and have high wavelength resources utilization rate with reducing the network risk.3.The RWA algorithm of service reliability constraint based on multi-link failure is proposed.The algorithm is also decomposed into a routing sub-problem and a wavelength assignment sub-problem.In the routing,it is possible to improve the reliability of the optical connection request by adding multiple protection sections to protect multiple working segments on the basic of traditional method which is using only one protection section to protect a certain working segment in the working path.The same wavelength assignment strategy as the single link is used for optical connection requests.The simulation results are analyzed.