一种基于SDN的网络负载均衡方案的设计与实现

发布时间：2018-04-13 10:29

本文选题：软件定义网络 + 链路负载均衡　；参考：《复旦大学》2014年硕士论文

【摘要】：负载均衡是保证网络服务质量的重要方法之一,它主要是通过合理调度网络和计算资源来扩展网络对数据的处理能力,从而避免网络拥塞,提高网络的性能和鲁棒性。当软件定义网络架构出现以后,如何利用OpenFlow协议,结合SDN集中式控制和软件可编程的特性,设计和实现网络负载均衡策略,仍有待于研究与完善。与传统网络架构相比,利用SDN来部署网络负载均衡方案有如下优势：(1) SDN可以在控制器层用软件实现网络负载均衡,不需要专用的硬件设备。(2) SDN相比传统网络更容易获得全局网络拓扑,更容易制定全局最优策略。(3) SDN可通过控制器来集中控制交换设备将转发策略统一配置到交换机,而不用逐一配置交换机。基于上述背景,本文主要的工作是设计并实现了一种基于SDN的网络负载均衡方案,目的是利用软件定义网络的集中式控制和软件可编程等相对传统网络架构的优势,设计一套灵活有效的负载均衡机制。网络负载均衡涉及到链路负载均衡和应用层负载均衡,因此本文分别从以下三个方面进行论述：第一,设计并实现一种链路负载均衡方案。利用软件定义网络的集中式控制的特性,我们可以通过定期发送相关协议包来获取全局网络拓扑,在此基础上本文实现了一种最优k条路径算法,选择出最优的k条冗余链路,最后我们制定评价模型对于每条候选链路进行评估,得到最有利于当前全局网络负载均衡的链路,最终将对应的转发策略部署到OpenFlow交换机的流表上。第二,设计并实现一种应用层负载均衡方案。因为一段时间内不同用户对于同一种网络服务请求的习惯和各自当时的网络状态都有差别,所以本文从用户层角度进行了一系列的数据采集,包括用户服务请求的频繁度、网络延迟和丢包率等参数。这些用户参数会发送到中间服务器,利用用户评分模型来对用户设定当前的优先级别,控制器会根据用户的优先级提供不同的转发策略。最终达到的效果是,按需求给不同用户分配服务资源,达到应用层负载均衡的效果。第三,为了检测上述网络负载均衡方案,同时也为了给网络管理人员提供更加方便有效的网络监控工具,本文还包括三个可视化工作：全局网络拓扑的可视化、链路状态的可视化和用户层数据采集可视化。
[Abstract]:Load balancing is one of the most important methods to guarantee the quality of service in network. It mainly extends the data processing ability of the network by reasonably scheduling the network and computing resources to avoid network congestion and improve the performance and robustness of the network.After the emergence of the software defined network architecture, how to design and implement the network load balancing strategy using OpenFlow protocol, combined with the characteristics of SDN centralized control and software programmable, still needs to be studied and improved.Compared with traditional network architecture, using SDN to deploy network load balancing scheme has the following advantages: 1) SDN can realize network load balancing in controller layer with software.Compared with traditional network, it is easier to obtain global network topology and make global optimal policy. SDN can centrally control the switching device to configure the forwarding policy to switch.Instead of configuring the switch one by one.Based on the above background, the main work of this paper is to design and implement a network load balancing scheme based on SDN.A flexible and effective load balancing mechanism is designed.Network load balancing involves link load balancing and application layer load balancing. Therefore, this paper discusses the following three aspects: first, a link load balancing scheme is designed and implemented.By using the property of centralized control defined by software, we can obtain the global network topology by sending related protocol packets periodically. On this basis, we implement an optimal k path algorithm and select the optimal k redundant links.Finally, we develop an evaluation model to evaluate each candidate link, and obtain the link that is most favorable to the current global network load balance. Finally, we deploy the corresponding forwarding policy to the flow table of the OpenFlow switch.Secondly, a load balancing scheme for application layer is designed and implemented.Because different users have different habits about the same kind of network service request and their respective network status for a period of time, this paper carries out a series of data collection from the user level, including the frequency of user service request.Network delay and packet loss rate and other parameters.These user parameters will be sent to the intermediate server and the user rating model will be used to set the current priority level for the user. The controller will provide different forwarding strategies according to the priority of the user.The final effect is to allocate service resources to different users according to their needs, and achieve the effect of load balancing in application layer.Third, in order to detect the above network load balancing scheme, and to provide network managers with more convenient and effective network monitoring tools, this paper also includes three visualizations: visualization of global network topology.Link state visualization and user layer data acquisition visualization.
【学位授予单位】：复旦大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.05

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