Research On The Methods Of Path Protection In Elastic Optical Networks

In recent years,with the rapidly development of cloud computing,high-definition television and Internet of things,the existing optical communication network transmission capacity is facing unprecedented challenges.Compared with the traditional wavelength division multiplexing network,the elastic optical network can improve the utilization of network spectrum resources through the following two technologies: the elastic optical networks has a more flexible bandwidth assignment granularity and can adaptively select different modulation formats according to the transmission distance.It is easy to cause elastic optical networks failure due to natural disasters,environmental impact and equipment aging.In addition,fiber transmission capacity can reach 400 Gbps or even1 Tbps or more,flexible optical network single link failure will cause a lot of data loss and request interruption.At the same time,routing and spectrum assignment is subjected to spectrum contiguity and spectrum continuity in elastic optical networks.Therefore,the problem of survivable routing spectrum assignment is an important research topic in optical network.The survivable routing spectrum assignment algorithm based on path protection is studied in elastic optical networks in this paper.Shared protection strategies are proposed to improve the spectrum utilization for single path protection technology and multipath protection technology,respectively.Firstly,in order to solve the problems of spectrum fragmentation and low spectrum utilization in single-path protection technology of elastic optical networks,a survivability single path shared path protection strategy,based on spectrum fragmentation aware and protection bandwidth reconstruction,is proposed in the third chapter.The strategy distinguishes the request duration to reduce the generation of spectrum fragmentation by using the first-fit or last-fit spectrum assignment algorithm.In the protection path spectrum assignment,the number of available spectrum resources consumed is minimized by reconstructing discontinuous available sharable spectrum blocks on the protection path to improve the protection bandwidth sharing degree.The simulation results show that the improved path protection strategy can improve the spectrum utilization and reduce the bandwidth blocking probability.Secondly,in order to solve the problem of low bandwidth sharing degree in survivability multipath technology,a survivability multipath strategy,based on spectrumavailability and protection bandwidth sharing degree aware,is proposed in the fourth chapter.In the single path protection,the strategy adjusts the link cost function of the protection path according to the link spectrum sharing degree,and improves the protection bandwidth sharing degree by selecting the minimum protection path.If the single path protection fails,the multipath protection strategy is designed.The strategy adopts the adaptive multipath spectrum allocation strategy,and introduces the shared protection mechanism to reduce the usage of free spectrum resources.Finally,if the request is blocked,the strategy reconfigures the request that working path is assigned in the sub-optimal path,and further improves the protection bandwidth sharing degree.The simulation results show that the proposed strategy can reduce the number of spectrum consumption assigned in the multipath spectrum assignment phase and reduce the network bandwidth blocking probability.