【作者】 张泽；

【导师】 秦华；

【作者基本信息】 北京工业大学 ， 计算机科学与技术， 2017， 硕士

【摘要】 随着移动互联网技术和应用的飞速发展,人们对移动业务应用提出了更高的需求,这对移动性管理技术保证移动终端在移动过程中通信业务的连续性并满足移动过程中的用户服务质量提出了更加严峻的挑战。基于OpenFlow协议的SDN网络架构将逻辑控制功能从传统网络设备中抽离出来形成控制平面,来提升其对数据平面的快速部署能力和灵活管控能力从而适应不同的网络应用需求,这对于网络层移动性管理机制的研究具有极大的促进作用。在当前现有的基于SDN网络的移动性管理方案中,网络层移动性管理机制大多需要在感知到节点移动后删除切换前路径上交换机的流表,然后重新计算并下发新的流表,即使考虑了重用切换前后路径中重合交换机上的流表信息,但没有考虑移动过程中的多个通信对端情况,产生了许多没必要的信令开销;并且在节点移动完成后控制器才重新计算路径并在整条新路径上下发流表,对切换时延产生一定的影响。而从大量的移动用户数据分析中得知,用户的移动行为服从幂律分布,80%以上的移动行为都集中在一块局部的区域内,而且移动位置预测相关研究表明预测用户移动行为的准确率可达70%以上,因此将移动位置预测相关研究应用到移动性管理来提前进行路径切换将提高切换性能。本文主要针对在SDN网络中支持IPv6网络层移动性管理机制进行研究,以降低移动过程中的切换时延和信令开销为关键目标,进而提升用户服务质量。首先,提出在SDN网络中如何维护无线WiFi网络环境下移动终端的当前位置信息,从而解耦IP的双重语义,在此基础上结合移动节点自身特点进而提出网络侧移动感知机制;然后,结合位置预测理论提出了一种支持预切换的IPv6移动性管理机制,该机制根据位置预测结果在移动发生前计算并下发切换路径流表到相应的交换机;最后,根据实际移动接入结果对切换路径进行路径优化。为了验证本文提出的移动性管理方案的可行性与有效性,首先基于ONOS控制器设计并实现该方案;然后利用Mininet-WiFi实验平台创建基于Mininet的支持OpenFlow协议的无线网络仿真实验环境,并设计测试实验方案。实验结果表明,与基于先删除移动前路径上交换机的流表再重新计算并下发新流表的方案相比,本文提出的移动性管理机制有效地降低了移动过程中的切换时延和信令开销,一定程度上保证了用户服务质量。更多还原

【Abstract】 With the rapid development of mobile Internet technology and application,people have put forward higher demand for mobile service application.This poses a more severe challenge to mobility management technology which ensure the continuity of communication service and the quality of user service in the mobile process.The SDN network architecture based on the OpenFlow protocol extracts the logic control function from the traditional network architecture to form a control plane to enhance its flexible control capabilities and fast deployment capabilities for the data plane to accommodate different network application requirements,which can actively contribute to the research on mobility management of network layer.In the current existing SDN-based mobility management solutions,the network layer mobility management mechanism needs to delete the flow tables of the switch on the path before handover,and then recalculate and download a new flow table.Even if the flow table information on the overlap switchs before and after handover path is considered,but without considering the communication terminals in the mobile process,a lot of unnecessary signaling cost is generated.What’s more,after the mobile node moves to another access point,the controller recalculates the path and sends the flow table to the whole new path,which will have some influence on the handover delay.A large number of data analysis that the user’s mobile behavior subject to power-law distribution,more than 80% of the mobile behavior is concentrated in a local area,and the research on position prediction shows that the accuracy of predicting user mobile behavior can reach more than 70%.Therefore,applying the research of mobile position prediction to mobile handover will improve the handover performance.This paper focuses on the IPv6 network layer mobility management mechanism in SDN network to reduce the handover delay and signaling cost in the mobile process and improve the quality of user service.Firstly,how to maintain the current location information of the mobile terminal in the wireless WiFi network environment based on SDN network is proposed,so as to decouple the dual semantics of the IP.Based on this,combining with the characteristics of the mobile node itself we put forward the mobile awareness mechanism of network side.Then,combined with the theory of location prediction,an IPv6 mobility management mechanism is proposed to support prehandover.This mechanism calculates and sends the handover path flow table to the corresponding switchs according to the position prediction result before the movement occurs.Finally,the path is optimized according to the actual mobile access result.In order to verify the feasibility and effectiveness of the mobility management scheme proposed in this paper,we first design and implement the scheme based on the ONOS controller,and then we use the Mininet-WiFi experimental platform to create a wireless network experiment environment based on Mininet and support the OpenFlow protocol,and we design the test experiment.The results of the experiments show that the mobility management mechanism proposed in this paper effectively reduces the handover delay and the signaling cost in the mobile process compared with the scheme of re-calculating new path and downloading the new flow table to the switches in the whole new path.To a certain extent,the new proposed mechanism ensures the quality of customer service.更多还原