Coflow Placement In Optical/electronic Hybrid Data Center Networks

In recent years,with the ever-accelerated development of big data and information,network applications increase constantly,so traditional compute mode gradually could not satisfy current large capacity of user demand,and more and more operations require computer cluster with quantity of computers for processing.However,maintaining so many operations and storage devices require a good deal of human power and financial resources,therefore most users choose to put these computation requirements to cloud or data center for processing,which causes the sharp increase of flow within data center.In order to provide better service and for the better transmission of network flow,the optimization of flow transmission in data center is a problem to be solved.Traditional data center network is based on tree network structure of electric packet switching.As the scale of data center network keeps expanding,traditional data center network confronts more and more serious efficiency problem and cost problem.The optical/electronic hybrid network put forward in recent years introduces optical switching technique.The advantages of optical-fiber network like high bandwidth and high transmission efficiency are fully taken of,which not only increase network capacity and network bandwidth,but also decrease the number of electric packet switches required in traditional data center network,thus lower network cost and energy consumption.Under optical/electronic hybrid network architecture,electric packet switching network and optical/electronic hybrid network can work parallel,which on the one hand can effectively reduce the handling capacity of packet switching network and improve network transmission performance;on the other hand,effective avoid the problem of single point of failure.In data center network,one task is often composed of several related sub-tasks.Therefore,there are always two or two more flows jointly completing a task.When we carry out optimization,we often take those related flows as a Coflow.Because each flow in a Coflow often compete for resource,optimizing the resource allocation in each flow of Coflow can effectively improve the whole network's resource utilization rate,reduce network blocking rate,and improve the processing speed of the demand in data center.Based on the placement problem of Coflow in optical/electronic hybrid network network of data center,the thesis constructs integral linear programming model for this problem,and introduces Column generation algorithm on the basis of this model,constructs the solving model composed of primal problem and sub-problem and improves the whole problem's operational efficiency by proposing a workable heuristic algorithm to replace sub-problem model.Meanwhile,the thesis also studies the placement problem of Coflow considering the time after the deadline of the transmission of Coflow,and put forward the optimization program of introducing postponing the placement problem of Coflow in queue.