Application Driven Evaluation, Design, and Implementation of Network Services and Resource Sharing Models

该提案的重点是在启用了服务质量的网络的环境中出现的问题以及应用程序对它们的使用。特别是，该提案的主要主题是在网络服务质量能力的潜在用户(即应用)与网络内这些服务质量能力的设计和实施之间发展更大的协同效应。为了实现这一目标，将沿着以下三个主要轴线开展工作：1.应用对网络服务和参数的使用和选择。这里的目标是确定对应用程序最重要的性能参数，并将该知识转换为{\emUtility}曲线，然后两个应用程序都可以使用该曲线来选择适当的网络服务，网络可以使用该曲线来智能地决定如何在资源争用的情况下最好地处理应用程序的流量。这不仅包括评估对不同类型的应用业务(例如，事务、音频、视频等)的带宽、损耗、延迟和抖动等传统服务质量参数的敏感度，还包括考虑涉及具有多个业务流的应用的更复杂场景，这些场景可能涉及不同的(动态)资源共享规则，具体取决于网络资源的可用性。支持网络和应用需求的性能监控、资源共享和动态资源分配算法。这里的目标是设计和评估特定的网络级机制，以支持动态资源共享和服务监控的应用需求。例如，某些业务流对“高质量”服务的访问可能取决于其他流的存在或不存在。设计和评估允许规范和实施此类功能的机制可以极大地提高网络提供对应用程序有用的服务的能力。挑战不仅在于设计能够支持应用需求的机制，而且在于将这些需求与现有的网络服务和能力相结合。例如，它可能需要高于和超出当前支持的服务之间的耦合，例如，确保音频流的小延迟，但前提是可以保证数据传输的给定最低速率。设计和实施网络设备中的可编程性，以支持应用程序需求和新的服务模式。该提案的最后一个维度的目标是通过利用许多新网络设备中提供的一些可编程性来调查支持应用程序需求和上述一些相关机制的可能性。这种方法的好处是，如果可行，它可以促进增量部署，并在新应用程序需要时促进新功能的引入。挑战在于确定该技术施加的功能和实现限制之间的适当权衡。对上述专题的调查将通过实验和分析两种方式进行。实验将在一个新成立的致力于多媒体和网络的实验室的背景下进行，该实验室包括作为应用流量来源的终端系统，以及由几家供应商提供的网络设备。此外，将与设备供应商密切合作，设计和实施新机制，以便更好地支持应用服务需求，以便在现有平台上纳入和测试。最后，参与Qbone Internet2试验床将使我们能够进行端到端的试验，而这些试验在仅有本地试验床的情况下是不可行的。具体地说，Qbone环境提供了初始可用的网络QoS服务类型的代表性样本，将在其上进行的实验将提供机会，不仅可以调查应用程序应该如何使用它们，而且还可以确定在它们的初始部署中可能出现的相关问题。

The focus of this proposal is on problems that arise in the context of QoS enabled networks and their use by applications. In particular, the main theme of the proposal, is the development of a greatersynergy between potential users of network QoS capabilities, i.e., applications, and the design and implementations of those QoS capabilities within the network. In order to accomplish such a goal, work will be carried out along the following three major axes:1. Use and selection of network QoS services and parameters by applications. The goal here is to identify performance parameters that are of most significance to applications, and translate that knowledge into {\emutility} curves that can then be used by both applications to select the appropriate network service, and by the network to make intelligent decisions on how to best handle an application's traffic in case of resources contention. This includes not only assessing sensitivity to traditional QoS parameters such as bandwidth, loss, delay, and jitter of different types of applications traffic, e.g., transactions, audio, video, etc., but also considering more complex scenarios involving applications with multiple traffic streams whichmight involve different (dynamic) resource sharing rules depending on the availability of network resources.2. Algorithms for performance monitoring, resource sharing, and dynamic resource allocation in support of both network and applications requirements. The goal here is to design and evaluate specific network levelmechanisms in support of applications requirements for dynamic sharing of resources and service monitoring. For example, access to a ``high quality'' service by certain traffic streams might be predicated on the presence or absence of other streams. Devising and assessing mechanisms allowing the specification and implementation of such functionality can greatly improve the ability of networks to deliver services that are useful to applications. The challenges are not only to design mechanisms capable of supporting applications requirements, but also to integrate them with existing network services and capabilities. For example, it may require coupling between services above and beyond what is currently supported, e.g., ensure small delay to an audio stream, but only as long as a given floor rate can be guaranteed to data transfers.3. Design and implementation of programmability in network devices in support of applications requirements and new service models. The goal of this last dimension of the proposal is to investigate the possibility of supporting applications needs and some of the above associated mechanisms, by leveraging some of the programmability that is being made available in a number of new network devices. The benefits of such an approach, if feasible, are that it can foster incremental deployment as well as facilitate the introduction of new capabilities if and when required by new applications. The challenges are to identify the appropriate trade-off between functionality and the implementation constraints that the technology imposes. The investigation of the above topics will be carried out through both experimental and analytical efforts. Experimentation will take place in the context of a newly established lab devoted to multimedia andnetworking, that includes end-systems as sources of application traffic, and networking equipment made available by several vendors. Furthermore, work on the design and implementation of new mechanismsto better support application service requirements, will be done in close collaboration with equipment vendors so as to facilitate their incorporation and testing on the available platforms. Finally, participation in the QBone Internet2 testbed will allow us to carry out end-to-end experiments that would not be feasible with only a local testbed. In particular, the QBone environment provides a representative sample of the type of network QoS services that will be initially available, and the experiments that will be carried out overit will offer the opportunity to investigate not only how applications should use them, but also to identify related problems that may arise in their initial deployment.