面向SDN的软件定义硬件计数器研究

发布时间：2018-11-11 16:06

【摘要】：软件定义网络(SDN)将数据平面与控制平面解耦,使网络变得更加灵活可控。在SDN架构中,为了支持SDN控制器获取全局网络统计信息从而高效管理整个网络,同时支持网络测量、入侵检测、流量工程等上层应用,SDN交换机需要维护大量多样的统计计数器。然而,目前这些SDN计数器通常是基于ASIC实现且只支持“请求响应”的被动统计模式,其实现面临一些严峻挑战:1)存储资源开销高;2)灵活性差;3)统计精度低。针对SDN计数器的这三大挑战,本文通过将计数器的定义与实现解耦提出了面向SDN的软件定义硬件计数器SDHC(Software Defined Hardware Counters)。本文的主要工作和创新点包括:1.提出了软件定义硬件计数器的概念和模型。SDHC模型通过将计数器处理分为三段,将计数器定义的管理实现在软件上来控制计数器的行为,实现了计数器定义与实现解耦,有效解决了传统实现方式的问题。利用按需分配思想,有效提高计数器利用率,从而减少存储开销;通过提供灵活便捷的SDHC南北向接口,允许控制器灵活控制计数器,从而提高了灵活性;通过引入主动上报计数器值的主动统计模式,避免了访问延时引起的统计误差,提高了统计精度。2.对SDHC关键技术进行深入研究。对软硬件间的消息定义及压缩方法进行深入研究,提高了软硬件之间的传输效率,减少了传输带宽需求。研究SDHC统计模式的分类和实现机制,提出了基于更新触发的实时模式和基于定时器触发的定时模式,有效地满足了多样化应用的高精度统计需求。同时,研究实时模式下计数器值返回消息的压缩方法,避免流的突发引起的高网络带宽问题。3.对SDHC实现模型进行详细设计。对SDHC实现模型中各模块的具体功能和实现进行详细设计,有效提高了各模块的工作效率,从而提高了SDHC整体性能。通过分析SDHC的相关行为,对SDHC南北向接口进行详细设计,使得控制器及上层应用能够灵活控制计数器。4.实现了SDHC原型系统,并对原型系统进行测试评价。结果表明,SDHC可以提供很高的更新性能和统计精度,同时SDHC造成的更新延时相比于控制器与交换机之间的传输延时可以忽略不计。综上所述,为了解决目前SDN计数器存在的问题,本文提出了面向SDN的软件定义硬件计数器SDHC。由于该模型具有低存储资源开销、高灵活性和高统计精度,对于SDN交换机的设计实现具有理论意义和实用价值。
[Abstract]:The software defined network (SDN) decouples the data plane from the control plane and makes the network more flexible and controllable. In SDN architecture, in order to support the SDN controller to obtain the global network statistics information and manage the whole network efficiently, it also supports the upper layer applications such as network measurement, intrusion detection, traffic engineering and so on. SDN switches need to maintain a large variety of statistical counters. However, at present, these SDN counters are usually based on the ASIC implementation and only support the passive statistical mode of "request response". The implementation of these counters faces some severe challenges: 1) high cost of storage resources, 2) poor flexibility, and 3) low precision of statistics. In view of these three challenges of SDN counter, this paper proposes a software defined hardware counter SDHC (Software Defined Hardware Counters). For SDN by decoupling the definition and implementation of the counter. The main work and innovation of this paper are as follows: 1. The concept and model of hardware counter defined by software are put forward in this paper. By dividing counter processing into three sections, SDHC model realizes the management of counter definition to control the behavior of counter on software, and realizes the decoupling of counter definition and implementation. It effectively solves the problem of traditional realization. By using the idea of according to demand distribution, the counter utilization ratio can be improved effectively, and the storage overhead can be reduced, and the controller is allowed to control the counter flexibly by providing flexible and convenient SDHC interface from north to south, thus improving the flexibility. By introducing the active statistical model of actively reporting the counter value, the statistical error caused by the access delay is avoided and the statistical accuracy is improved by 2. 2. The key technology of SDHC is studied deeply. The definition and compression method of message between software and hardware are studied in depth, which improves the transmission efficiency between software and hardware, and reduces the requirement of transmission bandwidth. In this paper, the classification and implementation mechanism of SDHC statistical pattern are studied, and the real-time mode based on update trigger and the timing mode based on timer trigger are proposed, which can effectively meet the needs of high precision statistics in various applications. At the same time, the compression method of counter value return message in real time mode is studied to avoid the problem of high network bandwidth caused by the burst of flow. The implementation model of SDHC is designed in detail. The specific function and implementation of each module in the SDHC implementation model are designed in detail, which effectively improves the working efficiency of each module and thus improves the overall performance of SDHC. By analyzing the related behavior of SDHC, the interface of SDHC is designed in detail, so that the controller and the upper application can control the counter flexibly. The prototype system of SDHC is implemented, and the prototype system is tested and evaluated. The results show that SDHC can provide high update performance and statistical accuracy, and the update delay caused by SDHC is negligible compared with the transmission delay between controller and switch. In conclusion, in order to solve the problems existing in SDN counters, this paper proposes a software defined hardware counter SDHC. for SDN. Because the model has low storage resource overhead, high flexibility and high statistical precision, it is of theoretical significance and practical value for the design and implementation of SDN switch.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.02

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