基于备份资源的SDN数据平面故障恢复方法

发布时间：2018-03-31 16:05

本文选题：软件定义网络　切入点：故障恢复　出处：《北京邮电大学》2017年硕士论文

【摘要】：在过去的十年间,随着信息和通信技术(Information and Communication Technology ICT)领域的巨大进步,传统互联网面临着严峻的挑战。例如,无线技术的快速发展促使移动管理领域不断展开新的研究;大型数据中心出现严重的能源消耗问题;对时间敏感的云端业务需要高质量的底层网络服务的支持等。近几年,为解决这些问题,学术界和工业界都将软件定义网络(Software Defined Networking,SDN)作为重点研究对象。SDN的核心是将控制平面与转发平面分离,同时引入网络可编程的思想。作为网络操作系统的SDN控制器与底层设备的远程分离使得人们可以随时随地对网络进行编程。SDN的良好特性使得新业务能够快速部署,新的学术研究方法可以轻松实现。目前,OpenFlow协议是将控制器和网络设备之间的通信标准化的最有潜力的技术,同时OpenFlow协议的广泛应用也使得SDN引起越来越多的学者的关注。SDN在不断发展的同时也有很多的问题亟需解决,而确保网络可靠性和稳定性的故障恢复问题就是其中之一。如果SDN中的链路或节点发生故障,则检测到故障的交换机需通知控制器更新流表或将数据迁移到预配置的路径以恢复故障。目前,有关SDN数据平面故障恢复方法的主要目标是实现故障恢复的同时,保证时延在可容忍范围内或确保数据包不丢失,但现有的故障恢复方法并未考虑这两方面:第一,故障恢复过程中的备份路径对存储资源的消耗;第二,在故障恢复过程中备份路径可能给网络带来的负载,及对网络整体性能的影响。基于以上讨论,本论文的主要贡献如下:(1)为了最小化备份资源的消耗并满足所需的故障恢复时延,提出了基于链路等级的故障恢复方法。该方法首先提出两个确定链路重要性等级的参数;然后提出三种用于不同等级的链路的备份策略;最后基于三种策略提出一种减少流表项的备份链路选取算法,该算法也能满足大部分业务的故障恢复时延要求。实验结果显示,所提出的方法可以使用尽可能少的流表项达到故障恢复的目的,同时满足重要业务所需的时延。此外,该方法在不同规模和连接率的网络中也具有良好的性能。(2)为了在满足故障恢复时延的同时,均衡备份路径给网络带来的负载,提出了基于负载均衡的SDN数据平面故障恢复方法,该方法首先将网络中传输的数据流根据其对时延的要求进行分类;然后,确定具有负载调节功能的备份路径选取策略,并提出了基于负载均衡的故障恢复算法。仿真实验表明,当预配置的备份路径上负载加重时,本文的方法可以有效地均衡该负载,并将重新计算的备份路径在相关交换机中进行配置,以确保恢复故障时能有效利用网络中的链路资源。
[Abstract]:In the past decade, with the great progress in the field of information and communication technology (ICT), traditional Internet is facing severe challenges. For example, the rapid development of wireless technology has led to new research in the field of mobile management. There are serious energy consumption problems in large data centers, and the need for high quality underlying network services to support time-sensitive cloud business, etc., in recent years, to solve these problems, The core of the SDN is to separate the control plane from the forwarding plane, the core of which is to separate the control plane from the forwarding plane. At the same time, the idea of network programming is introduced. The remote separation of the SDN controller and the underlying device, which is the network operating system, enables people to program the network anytime and anywhere. New academic research methods can be easily implemented. The OpenFlow protocol is currently the most promising technology for standardizing communication between controllers and network devices. At the same time, with the wide application of OpenFlow protocol, more and more scholars pay attention to SDN. At the same time, there are many problems that need to be solved. One of them is to ensure the reliability and stability of the network. If a link or node in SDN fails, The switch that detects the fault needs to notify the controller to update the flow table or migrate the data to the pre-configured path to recover the fault. At present, the main goal of the SDN data plane fault recovery method is to achieve fault recovery at the same time, To ensure that the delay is within the tolerable range or to ensure that data packets are not lost, but the existing fault recovery methods do not consider these two aspects: first, the consumption of storage resources by the backup path in the fault recovery process; second, The load that the backup path may bring to the network and its impact on the overall performance of the network during fault recovery. The main contributions of this thesis are as follows: (1) in order to minimize the consumption of backup resources and satisfy the required delay of fault recovery, a link level based fault recovery method is proposed. Then three backup strategies for different levels of links are proposed. Finally, a backup link selection algorithm based on the three strategies is proposed, which can also meet the fault recovery delay requirements of most services. The experimental results show that, The proposed method can use as few flow table items as possible to achieve the purpose of fault recovery, and at the same time satisfy the delay required for important traffic. This method also has good performance in the network with different scale and connection rate. In order to balance the load brought by backup path at the same time to meet the delay of fault recovery, a method of SDN data plane fault recovery based on load balancing is proposed. The method first classifies the data streams transmitted in the network according to its requirements for delay, and then determines the backup path selection strategy with load adjustment function, and proposes a fault recovery algorithm based on load balancing. The simulation results show that, When the load on the pre-configured backup path is increased, the method in this paper can effectively balance the load, and configure the recalculated backup path in the relevant switch to ensure that the link resources in the network can be utilized effectively when the fault is recovered.
【学位授予单位】：北京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP393.0

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