With the emergence of SDN(Software Defined Network), a centralized network, the network research around SDN innovation has continued to rise. One branch which focuses on QoS(Quailty of Service) control is especially favored by the researchers. Reasons can be summed as below: firstly, the demands of QoS network applications show diversified and finer granularity; secondly, centralized idea of SDN benefits to break the restriction of flat architecture of traditional network, provides more natural and elegant network QoS resolution. As an important QoS metric, network delay is more difficulty to control due to its variability and high dynamic. This paper makes a comprehensive and deep survey on related works about QoS delay control in SDN network, summarizing current achievements and also pointing out problems still exist, in order to provide a useful reference to future studies.%随着SDN 这种中心化网络理念的提出,近年来,网络领域围绕SDN 的创新网络研究热度就一直居高不下.其中,以网络QoS 控制为代表的研究分支尤其受到研究者的青睐.究其原因主要有两个: 首先,各种网络应用对网络QoS 的需求表现出多样化、精细化,并日趋强烈的特点;其次,由于在传统网络中相关研究受到网络扁平化问题的制约而遭遇瓶颈,而SDN 这种创新的网络架构理念恰恰有助于突破传统网络的制约,为QoS 的研究和应用提供助力.作为网络QoS 的重要指标之一,网络时延因其动态性强而具有更高的控制难度,本文重点围绕时延控制方面的相关研究,通过梳理现有研究在时延控制方面所做的工作,总结现阶段研究方向上取得的成果和存在的问题,为后续相关研究提供有益的借鉴和参考.
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