软件定义网络的研究及应用

发布时间：2018-11-09 13:48

【摘要】：虚拟化应用伴随着云计算的发展而呈现爆炸性增长。传统网络中，为了保证网络正常运行，在不同网络层级上有大量互不相干的网络协议。这种趋于静态化的传统网络并不能适应服务器上的虚拟机快速迁移而对网络带来的压力和挑战。传统网络中的分层机制使得每一层都需要考虑链路回环，网络收敛，不同网络设备对网络视图的一致性等问题，对网络知识的学习发生在网络中的每台网络设备上，只要有一台网络设备因为配置或者故障等原因无法学习网络知识时，会对整个网络造成影响。软件定义网络分离了网络的转发层面与控制层面。在ONF(Open Network Foundation)组织定义的Openflow协议中，规定了网络控制器与Openflow交换机之间的通信机制。控制器通过下发流表对Openflow交换机进行控制，当Openflow交换机接收到网络报文后，根据流表进行报文的转发，流表涵盖了IOS网络模型中第2层至第4层的控制信息。利用Openflow协议提供的多种报文，控制器能够生成全网视图，进而对网络进行集中控制。本文依据Openflow协议，制作了SDN网络控制器TinyController，该TinyController通过流表控制Openflow交换机，使Openflow交换机表现出二层交换机的形态。通过构造LLDP报文，，使该TinyController能够进行拓扑探测。将网络拓扑以有向图的形式存储在TinyController中，使用贪心算法，生成网络拓扑中的最优路径。根据TinyController进行拓扑探测的特点，当链路度量值相等时，改进贪心算法，降低了算法的时间复杂度。本文最后搭建实验平台对该TinyController进行测试，度量了TinyController对Openflow交换机通信产生的延迟。分析了TinyController产生的流表。在TinyController中生成了网络拓扑并最终生成最优路径。
[Abstract]:With the development of cloud computing, virtualization applications are increasing explosively. In the traditional network, in order to ensure the normal operation of the network, there are a large number of unrelated network protocols at different network levels. This kind of static traditional network can not adapt to the pressure and challenge brought by the fast migration of virtual machine on the server. Because of the hierarchical mechanism in the traditional network, every layer needs to consider the problems of link loop, network convergence, consistency of network view between different network devices, and the learning of network knowledge takes place on every network device in the network. As long as a network device is unable to learn network knowledge due to configuration or failure, it will affect the whole network. The software defines the network to separate the forwarding level from the control level. In the Openflow protocol defined by ONF (Open Network Foundation), the communication mechanism between network controller and Openflow switch is defined. The controller controls the Openflow switch through the downflow table. When the Openflow switch receives the network message, it forwards the message according to the flow table. The flow table covers the control information from the second to the fourth layers in the IOS network model. Using various packets provided by Openflow protocol, the controller can generate the view of the whole network and control the network centrally. Based on the Openflow protocol, a SDN network controller, TinyController, is made. The TinyController controls the Openflow switch through a stream table, which makes the Openflow switch behave as a layer 2 switch. By constructing LLDP packets, the TinyController can be used for topology detection. The network topology is stored in TinyController as a directed graph and the optimal path in the network topology is generated by greedy algorithm. According to the characteristics of TinyController topology detection, when the link weights are equal, the greedy algorithm is improved and the time complexity of the algorithm is reduced. Finally, the experiment platform is built to test the TinyController, and the delay caused by TinyController to Openflow switch is measured. The stream table generated by TinyController is analyzed. The network topology is generated in TinyController and the optimal path is finally generated.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.09

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