Regulation, Scheduling, and Flow Control for Quality of Service Support

建议的项目将调查一些问题，在不同的服务质量（QoS）的有效支持。由于网络资源的稀缺和新应用的出现，当前的互联网从尽力服务发展到支持不同QoS的服务被认为是至关重要的。IETF首先在集成服务的上下文中，最近在区分服务的上下文中，对这个问题进行了探讨。集成服务工作的关键问题之一是网络核心中的每个微流调度缺乏可扩展性，而区分服务的基本原则是将每个微流操作移动到网络边缘，只处理网络内部的宏流。然而，仍然需要一些关键的业务元素，例如调节器（在边缘处对微流以及在不同子网络的边界处对宏流进行整形、管理和标记）和调度器（跨越不同的宏流和服务类别）来提供不同的QoS。更高的多路复用增益也寻求通过看流量统计，而不是在最坏的情况下。此外，还提出了使用微流级的端到端流控制和监管/标记以及宏流级的丢弃（RIO）/调度的组合的方案，以提供有保证的QoS沿着与使用附加可用带宽的能力的组合。本提案的目的是设计这些关键的流量控制元素-调节器、路由器和流量控制机制-以便不仅提供所需的不同QoS，而且以最大化网络效用的方式这样做。 为了实现这一目标，该项目将依赖于研究人员及其合作者最近开发的建模和分析框架。该框架提供了一个统一的数学模型（基于流量包络/服务曲线/服务过程的概念），监管机构和分销商，以及一个简单的方法来分析分叉加入网络的这些元素（或没有窗口/速率流控制）。特别是，研究人员以前的工作已经表明，整个网络的影响可能会减少到一个等效的单一元素与（端到端）的服务曲线的各个元素的服务曲线，使用一个简单的组成规则。此外，这样的网络的最坏情况和概率的端到端的性能，然后很容易获得在此端到端的服务曲线。由于该框架是可分析的，人们可以“反转”的分析结果，以获得有效的交通控制元素的设计规则。更有趣的是，该框架允许表示一个复杂的服务曲线为一个单一的交通控制元素，作为一个网络的简单服务曲线。 然后可以利用这种表示来合成复杂但高效的调节剂和抑制剂。因此，这个建模框架提供了一个系统的方法来分析，设计和综合业务控制元素的区分服务网络。 特别是，拟议的项目将导致以下：它将导致更有效的监管机构和监管机构的综合。它将在区分服务网络的范围内开发其他有保证的服务（除租用线路仿真外）。它将产生更好的准入控制方案的概率服务。对于保证服务和概率服务，它还将通过定价将网络资源有效地分配到不同流的服务曲线中。在具有某些最低要求的自适应服务的情况下，它将导致更好地理解简档内和简档外流量之间的相互作用，以及如何利用这种相互作用来增强现有的自适应机制，如TCP。

The proposed project will investigate a number of problems in the efficient support of different qualities of service (QoS). Due to the scarcity of network resources and the emergence of new applications, it is considered crucial that the current internet evolve from a best effort service to one that supports different QoS. This problem was explored in the IETF first in the context of integrated services and more recently in the context of differentiated services. One of the key problems with the work in integrated services was the lack of scalability of per-microflow scheduling in the core of the network, and the basic tenet of differentiated services has been to move per-microflow operations to the edge of the network and deal with only macroflows in the interior of the network. Nevertheless, some of the key traffic elements such as regulators (to shape, police, and mark microflows at the edge as well as macroflows at the boundary of different subnetworks) and schedulers (across different macroflows and service classes) are still needed to provide the different QoS. Higher multiplexing gains are also sought by looking at flows statistically rather than in the worst case. Moreover, schemes that use a combination of end-to-end flow control and policing/marking at the microflow level and dropping (RIO)/scheduling at the macroflow level have also been proposed to provide a combination of assured QoS along with the ability to use additional available bandwidth. The objective of this proposal is to engineer these key traffic control elements - regulators, schedulers, and flow control mechanisms - so as to not only deliver the different QoS desired, but to do so in a manner that maximizes the network utility. In order to accomplish this objective, the project will rely on a modeling and analysis framework that has recently been developed by the researcher and his collaborators. This framework provides a unified mathematical model (based on the notion of traffic envelopes/ service curves / service processes) for regulators and schedulers as well as an easy way to analyze fork-join networks of such elements with (or without window/rate flow control). In particular, the researcher's prior work has shown how the impact of the entire network may be reduced to that of an equivalent single element with an (end-to-end) service curve given in terms of the service curves of the individual elements using an easy composition rule. Furthermore, the worst-case and probabilistic end-to-end performance for such networks is then easily obtained in terms of this end-to-end service curve. Since the framework is analyzable, one can "invert" the results of the analysis to derive rules for the design of efficient traffic control elements. More interestingly, the framework allows for the representation of a sophisticated service curve for a single traffic control element, as a network of simple service curves. This representation can then be exploited to synthesize complex but highly efficient regulators and schedulers. This modeling framework therefore provides a systematic way to analyze, design, and synthesize traffic control elements for differentiated services networks. In particular, the proposed project will lead to the following: It will result in the synthesis of more efficient regulators and schedulers. It will develop other guaranteed services (besides leased line emulation) in the context of differentiated services networks. It shall produce better admission control schemes for probabilistic service. For both guaranteed and probabilistic service, it will also lead to efficient allocation of network resources into service curves for different flows via pricing. In the case of adaptive service with certain minimum requirements, it will lead to a better understanding of the interplay between the in-profile and out-of-profile traffic, and how this interplay may be exploited to enhance existing adaptive mechanisms such as TCP.