软件定义网络系统中面向流的调度算法

The Flow-oriented Scheduling Algorithms In SDN System

软件定义网络(Software Defined Networking,SDN)由于其控制和转发分离的特性,在学术研究和工程上广泛应用于数据中心等领域.SDN体系结构中没有规定特定转发机制,而是通过更改控制模块或者开发具体的控制器App来实现.NOX是斯坦福大学在2008年提出的第1种OpenFlow控制器,它基于OpenFlow协议提出了类似传统路由器OSPF协议的最短路径转发算法,即NOX路由模块(NOX routing module).该算法通过SDN系统控制链路收集全局交换机静态参数,并没有利用SDN系统的优势来获得交换机运行时的状态信息来提高转发性能.该文根据SDN集中控制以及控制器计算能力可扩展等特性,设计SDN结点、路径和流的评价体系,将各体系分支的评价指标作为交换机运行时的状态信息参数,在此基础上提出均衡算法.该Online算法具有自适应性和启发性,有效地提高了SDN在转发过程中(特别是针对大数据量)的运行效率.

Software Defined Networking（SDN）has been widely applied to many areas by research and operational communities,such as Data Center Network,with the nature of decoupling control and data planes.There are no predefined routing algorithms strictly limited to SDN＇s design strategies, which are recommended to be realized by reconstructing or programming at the controller layer.NOX,which is the first controller designed by researchers in Stanford University,has presented a simple shortest path routing algorithm based on OpenFlow,i.e.NOX routing module.This module has realized the shortest path routing based on traditional routing mechanism,while it hasn＇t fully taken the advantages of SDN,such as sensing and detecting status of the network.The NOX routing module just try to gather some static information from all of the switchers through secure channel.To make full use of central control of SDN and its scalability of controller,this paper have developed an evaluation system to estimate the priority value of the nodes,links and flows in SDN,which is considered as the runtime state information that used as the parameters in balance algorithm,which is online and adaptive heuristic,with a module to collect real-time status information and another module to assess this status.The experiments have proofed that these ameliorations have improved the efficiency of flow forwarding,especially in the scenario with high burden of routing large scale of data.