Research On Routing Spectrum Allocation Algorithm In Elastic Optical Network With Hybrid Path Protection

With the increasing network traffic,the types of business requirements tend to diversify,which promotes the development of optical networks.Since the wavelength division multiplexing optical network uses a fixed grid to allocate spectrum resources,it can not allocate spectrum resources more finely and flexibly for service,which will cause serious resource waste.Therefore,people have proposed a more efficient,more fine-grained,elastic optical networks that can allocate resources flexibly.The optical fiber link in the elastic optical networks carries a large amount of important communication traffic information,and the huge loss caused by the failure of the optical fiber link cannot be ignored.Therefore,the research on the survivability of the elastic optical networks is very important.In this thesis,the path protection of elastic optical network is studied.By combining the advantages of single path protection and multi-path protection,the bandwidth blocking probability can be reduced under the premise of ensuring service reliability.The thesis studies the survivability strategy of hybrid single-path dedicated protection and multi-path dedicated protection in elastic optical networks.In the elastic optical network scenario where services arrive dynamically,the path conditions between the source node and the destination node of a specific service request may be different.Therefore,under different path states,single-path dedicated protection and bandwidth splitting multi-path dedicated protection may have different advantages and disadvantages.In order to reduce the bandwidth blocking probability,in this thesis,a path coefficient is defined.The proposed path selection strategy is based on K shortest paths algorithm to obtain multiple paths with uncorrelated links by the path first calculation with the minimum path coefficient.The proposed hybrid dedicated path protection algorithm uses the highest spectral efficiency of the path,the number of hops of the path and the maximum available spectrum information on the path to allocate the spectrum.The hybrid dedicated path protection algorithm preferentially selects the solution that consumes the least spectrum resources among the generated survivability solutions.The simulation results show that the proposed hybrid dedicated path protection algorithm has obvious improvements in bandwidth blocking probability and spectrum utilization rate compared with the comparison algorithms.When the load on the COST239 network is 320 Erlang,the bandwidth blocking probability of the proposed algorithm is at least reduced by 29.8%compared with the comparison algorithm;when the load on the USNET network is 150 Erlang,the bandwidth blocking rate is at least reduced by 12.5%.When the COST239 network is 320 Erlang,the spectrum utilization rate of the proposed algorithm is at least increased by 5.6% compared to the comparison algorithm;when the load on the USNET network is 150 Erlang,the spectrum utilization rate is at least increased by 1.8%.In this thesis,the partial bandwidth protection which divides the bandwidth into multiple paths is considered to reduce the demand of redundant protection resources.At the same time,considering the existence of redundant resources in multi-path protection,the realization of sharing redundant resources can further reduce the bandwidth blocking probability.In this thesis,the spectrum resources of optical fiber link are divided into working spectrum region and protection spectrum region.The working spectrum region only allocates working bandwidth and the protection spectrum region only allocates protection bandwidth.Then,a formula for dynamically updating link weights according to working spectrum occupancy is proposed.Three spectrum allocation strategies are designed to dynamically generate reasonable allocation schemes based on path information: single working path allocation strategy,double path allocation strategy and three path allocation strategy.The spectrum partition single/multi-path sharing protection algorithm contains these three strategies,and the least cost value strategy is selected through the cost calculation formula proposed in the thesis.Finally,through many experiments,the best proportion of protection spectrum and working spectrum of USNET and COST239 network topologies under different protection requirements is obtained.Through experimental simulation comparison,the spectrum partition single/multi-path sharing protection algorithm proposed in this paper has better performance in terms of bandwidth blocking probability compared with the comparison algorithms.When the USNET network load is 330 Erlang and the protection degree is limited to q=0.5,the proposed algorithm reduces the bandwidth blocking probability by at least 5.3%compared with the comparison algorithm.When the load in the COST239 network is 600 Erlang under the condition that the degree of protection q=0.5 is limited,the bandwidth blocking probability of the proposed algorithm is at least about 30.1% lower than that of the comparison algorithm.