Research On SDN Flow Scheduling Scheme For Data Center Network

With the rapid development of network services such as search engines,social networks,e-commerce,etc.,there has been an explosive growth in network traffic,which has brought serious challenges to data center network.The existing TCP/IP network has many inherent shortcomings that can't meet the needs of the rapid development of data center network.Software Definition Network(SDN)is a new network paradigm that separates control and forwarding to enable logic centralized control.At present,it's a research hotspot that SDN architecture is applied to data center network.Data center network based on SDN has significant characteristics of short flow and long flow,that is,less than 20% of long flow contributes more than 80% of the traffic.Besides,the short flow is sensitive to delay,while the long flow is sensitive to throughput.According to the characteristics of long flow and short flow in data center network based on SDN architecture,the technology of flow scheduling is studied.The main works are as follows:1.A flow scheduling scheme based on preemptive priority and time-division is designed.The preemptive queuing model is analyzed theoretically,and the waiting delay of various priority flows is calculated.The time-division strategy is adopted to solve the problem of long flow blocking.The time-division scheduling trigger conditions,exit conditions and time slice allocation are designed.The flow detection module in switch adopts the detection method of combination the port number with the traffic statistics to separate the diffident flows,and then the flows are processed in flow scheduling module.Simulation verification in the Mininet environment,compared with FIFO,Pri and PrmPri,PrmPri-DT effectively reduces the average delay of short flow,and also solves the problem of long flow blocking.2.A multi-path flow scheduling scheme based on adaptive traffic allocation is designed.The packet-in message of open flow protocol is extended to enable controller to identify long flow and short flow.The multipath mode is analyzed,and the Dijkstra algorithm is iteratively used to find multipath.According to the network topology and link bandwidth,the controller calculates the weight of paths,selects the available paths and calculates the flow distribution ratio.If it is the long flow,all the available paths are sent to the corresponding switches;on the other hand,the path with maximum weight is sent to the corresponding switches.On the switch side,the dynamic rotation algorithm is used for long flow to implement traffic dynamic distribution.Simulation verification in the Mininet environment,compared with Single-Path and ECMP,the adaption weight multipath effectively improves the long-flow throughput and link rates.