Research On Resource Optimization For Flexible Spectrum Optical Network And SDN Enabled Optical Network Control Method

Driven by the rapid development of high-speed broadband services,the evolution of all-optical network technology presents two major trends:the reform of the transport layer and the reconstruction of the control layer.Therefore,how to optimize the spectrum resources allocation of transport layer and how to improve the network architecture and implementation method of control layer,to make the optical network more flexible and efficient,have become the key research topics in the field of optical networking technology in recent years.Based on the resource optimization for flexible spectrum optical network and software defined networking(SDN)enabled optical network control method,this doctoral dissertation intensive studies in several aspects such as spectrum allocation algorithms,design of control and adjustment scheme for flexible control layer,and realization of OpenFlow-based centralized intelligent control.Some innovative achievements have been obtained.The main work and innovative contributions are listed as follows:(1)A routing and spectrum assignment(RSA)algorithm based on spectrum consecutiveness is proposed.In order to solve the problem of dynamic routing and spectrum assignment in flexible spectrum optical networks,a novel fragmentation-and misalignment-aware RSA algorithm based on spectrum consecutiveness is proposed.In the process of routing computation,this algorithm minimizes the segmentations as far as possible that the new connection for bearer service on the continuous spectrum of the optical fiber link,avoiding the more serious spectrum fragmentation.In the process of spectrum allocation,this algorithm minimizes the impact of the new connection for bearer service on the spectrum resources of the adjacent links,avoids to break the alignment of available spectrum blocks between the bearing link and its adjacent links,so as not to affect the adjacent link pair bearing the future connection requests.The simulation results show that,under the circumstances of three line rates and five line rates,compared with the average blocking probability of the four traditional RS A algorithms,the blocking probability of the fragmentation-and misalignment-aware RSA algorithm based on spectrum consecutiveness can reduce more than 26%and 12%respectively,and improve the network performance.The cost of the algorithm performance improvement is to understand the topology and resource usage of the whole network.With the existing technology,centralized routing can be achieved by both path computation element(PCE)and software-defined optical network(SDON).If one of the above techniques is chosen as the control plane of the flexible spectrum optical networks,the premise can be guaranteed and the algorithm is feasible.(2)An OpenFlow-based adaptive adjustment scheme of optical path resources is proposed.The method of adjusting the link resource in one step cannot meet the requirements of dynamic,flexible and adaptive traffic of the optical network.According to the requirement of adaptive elastic adjustment of optical path resources and spectral resources in optical network,an OpenFlow-based adaptive adjustment scheme of optical path resources is proposed.In the scheme,three meaningful applications of upper layer are pointed out,including Diff-Serv in optical domain,transmission performance adjustment on optical path,and solutions to the problem of wavelength conflict/spectrum overlap,where the first two belong to the scope of optical path adjustment,while the third one is a spectrum adjustment for the services.In terms of transmission performance adjustment on optical path,a mathematical model of optical path transmission performance adjustment is established firstly.Based on it,a new device link quality equalizer(LQE)is built.Essentially,the proposed control scheme applies OpenFlow to the optical networks,and implements the adaptive software control on optical connections in dynamic scenarios.The novelty is that it presents a method of dynamic performance configuration for the network in the operation,which makes the constraints of network routing and resource allocation less,thus reducing the blocking rate.The adaptive elastic adjustment of optical path resources and spectral resources in the optical network is realized.(3)The experimental method of dynamic performance control on intelligent channel based on OpenFlow is studied.With the advent of programmable devices and flexible software control methods,the dynamic performance configuration has the physical basis and protocol foundation for implementation.In order to solve the intelligent control problem of flexible optical networks,the research on an experimental method of dynamic performance control on intelligent channel based on OpenFlow is carried out.Three hardware experiments including Diff-Serv in optical domain,quality of transmission(QoT)-aware adaptive adjustment of optical path transmission performance,and OpenFlow-based adaptive spectrum adjustment,are carried out on the experimental platform,to study the experimental method of dynamic performance control on intelligent channel.In the experimental test-bed,the intelligent performance control function is added to the control plane,and the programmable node and device that can implement the intelligent performance control are introduced to the transport plane.By introducing a number of links or nodes that can adjust the performance parameters,the failed service that due to performance constraints in the original network can be routed successfully.As a result,the feasibility and effectiveness of the proposed dynamic performance configuration scheme for the networks in the operation are verified.