摘要软件定义网络（SDN）的核心思想是数据转发与控制逻辑的分离,即将网络控制机制集中在网络中心控制器中。在传统网络中，选择好路由协议后，数据传输过程就有了确定的路径，不能随着网络状况的改变而对其进行调整。SDN网络核心理论是将路由器（交换机）中的数据转发和控制层面分离，控制层部署在SDN控制器。
通过SDN技术，在控制器端设计新的路由协议，即SDN路由，该路由协议可以根据不同的网络状态进行路由快速切换或者重新路由选择。实验所用的控制器为Floodlight控制器，本次实验所用的路由算法为Bellman-ford算法，实现按照该算法来选择和更换路由，达到数据转发与控制层面分离，实现更改路径的功能。
本次实验首先通过Vmware+Mininet搭建SDN环境，然后对Floodlight路由算法改进，用Bellman-Ford算法进行节点路径的计算，从而通过Floodlight控制器完成路径的更换，通过ping过程来检查并输出具体的端口和路径，最后完成对实验结果的分析。28149
毕业论文关键词  SDN Routing，OpenFlow协议，Dijkstra路由算法，Floodlight控制器
毕业设计说明书外文摘要
Title    Multi Strategy routing algorithm based on SDN              
Abstract
The software defined network is based on a basic idea about the separation between control logic and data forwarding，and it makes the network control mechanism focus on the network controller.In the traditional network,once the data transmission process chooses the routing protocol，it could not change and adjust as the network conditions changing. The core theory of SDN network is the separation between the data forwarding and control layer which are in routers (switches)，and the control layer is deployed in SDN controller.
By the technology of SDN, design of new routing protocol in the controller, namely SDN routing, the routing protocol can quickly change routing or re routing according to different network status. The controller used in the experiment is the Floodlight controller.In the experiment I modified routing algorithm to the Bellman-ford algorithm.The routing can be chosen according to the   the algorithm,which we can achieve the data forwarding and control the level of separation.
In this experiment，I made the SDN network environment with VMWare and mininet .Then，I use the Bellman-Ford algorithm to calculate the routing .So the routing can be chosen and changed .According to the process of ping，we can check and print the concrete port and routing .Finally，the analysis of the experiment results should be completed .
Keywords  SDN Routing，OpenFlow protocol，Dijkstra routing algorithm，Floodlight controller
 目   次
1引言 3
1.1SDN网络背景3
1.2SDN网络概述3
1.3 OpenFlow协议简介4
1.4SDN网络路由技术研究背景6
1.5论文主要结构和内容 6
2 SDN网络环境搭建 8
2.1SDN网络环境概述8
2.2SDN软件工具和技术简介8
2.3环境搭建过程 10
2.4本章小结 14
3 Floodlight解读16
3.1Floodlight模块架构概述 16
3.2Floodlight模块分析 16
3.3Floodlight各模块处理Packetin消息顺序18
3.4Floodlight路由机制 19
3.5本章小结 22
4 路由算法详解 23
4.1Dijkstra路由算法概述 23
4.2Bellman-Ford路由算法概述 23
4.3Bellman-Ford路由算法和Dijkstra路由算法对比分析25
4.4本章小结 26
5 实验过程详解 27
5.1Python语言自定义拓扑环境 27
5.2Bellman-Ford路由算法源码 28
5.3程序运行结果与分析 31
5.4 本章小结36
6 结束语37
6.1论文总结 37
6.2 展望37
结论38
致谢 39
参考文献 40 Vmware+Mininet基于SDN的多策略路由算法:http://www.751com.cn/jisuanji/lunwen_22898.html