Regions: A new architectural capability in networking

互联网的原始图片经常描绘出由连接的“云”连接的主机或局域网的小集合。事实要复杂得多。Internet的ip级结构由大量组成网络组成，每个组成网络在部分或全部传输技术、路由协议、管理模型、安全策略、QoS功能、定价机制和类似属性方面都有所不同。在此基础上，一种全新的应用层覆盖和内容分发网络结构正在迅速发展，这种结构在上面提到的各种方式上同样多样化。实际上，当前Internet结构中的任何横向切片都揭示了一个松散耦合的联邦，由单独定义、操作和管理的实体组成，这些实体在不同程度上相互连接，并且在内部需求和实现方面通常存在巨大差异。直观地说，很自然地认为这些实体存在于网络的一个区域中，每个区域都有连贯的内部技术和政策，每个区域根据一些定义的规则和政策集管理其与网络其他区域的交互。本提案的论点是，区域的这个基本的、一般的概念是管理互联网及其后继者日益复杂的需求的有力工具，因此应该成为网络体系结构的一个明确的、一流的组成部分。建议区域概念的许多用途共享一组定义良好的核心思想和操作，因此将“区域”概念从该概念的任何特定用途中分离出来并将其作为独立的、可重用的抽象提供是有用的。进一步建议，区域抽象可以作为一个具体的软件实体来实现，这样做将为协议设计者和实现者在堆栈的所有级别提供逻辑结构化的、可扩展的、高性能的访问一个重要的功能类别。区域是一个群和某个空间中的界的泛化。区域的两个定义概念是一组包含的成员，它们共享一些共同的不变量，以及一个边界，它允许我们捕捉进入和离开区域时所采取的动作的概念。此外，它能够自适应其大小或使用模式的变化，从而允许在对可伸缩性、性能和效率的广泛不同需求下应用相同的抽象。思想在网络的许多地方都很有用，可以用来解决诸如规模、分布、效率、异构性、成本回收等问题。本研究提出定义和发展区域抽象，并探索其作为网络通用机制的效用。这项研究将通过三个相互关联的活动的几个阶段进行。首先是区域抽象本身的开发和定义，重点是需求、功能选择、抽象操作和相关问题。其次是设计和构建区域实体的原型实现，重点是适当的算法和自适应策略。第三是通过三个实例问题来检验和验证区域概念。这些示例有两个目的：探索拥有可用区域的效用，并进一步完善和改进区域的定义。它们的选择是为了强调区域抽象的不同方面。其目的是，区域是一种中立的机制，用于解决单个网络层内和跨层的许多问题。这项研究将有助于更好地理解多层管理，以及一层管理对另一层管理的可控影响。这项研究有望为适应规模和使用模式的变化制定一个决策框架。最后，这项研究预计将提供一个更好的理解，在每个例子领域的问题，出现在那里，以及如何解决它们。

Naive pictures of the Internet frequently portray a small collection of hosts or LAN's connected by a "cloud" of connectivity. The truth is more complex. The IP-level structure of the Internet is composed from a large number of constituent networks, each of which differs in some or all of transmission technologies, routing protocols, administrative models, security policies, QoS capabilities, pricing mechanisms, and similar attributes. On top of this, a whole new structure of application-layer overlays and content distribution networks, equally diverse in the sorts of ways mentioned above, is rapidly evolving. Virtually any horizontal slice through the current Internet structure reveals a loosely coupled federation of separately defined, operated, and managed entities, interconnected to varying degrees, and often differing drastically in internal requirements and implementation. Intuitively, it is natural to think of each of these entities as existing in a region of the network, with each region having coherent internal technology and policies, and each region managing its interactions with other regions of the net according to some defined set of rules and policies.The thesis of the present proposal is that this basic, general notion of a region is a powerful tool for managing the increasingly complex demands on the Internet and its successors, and thus should made into an explicit, first-class component of the network architecture. It is suggested that the many uses of the region concept share a well-defined set of core ideas and operations, and that it is therefore useful to separate the concept of "region" from any specific use of the concept and provide it as an independent, reusable abstraction. It is further suggested that the region abstraction can be implemented as a concrete software entity, and that doing so will provide protocol designers and implementers at all levels of the stack with logically structured, scalable, high-performance access to an important classof functionality.The region is a generalization of a group and a bound in some space. The two defining concepts of a region are a set of contained members, which share some common invariants, and a boundary, which allows us to capture the notion of actions taken when entering and leaving the region. Furthermore, it is capable of self-adaptation to changes in its size or usage patterns, allowing the same abstraction to apply under widely differing demands on scalability, performance, and efficiency. Ideas are found useful in many places in networking to address problems such as scaling, distribution, efficiency, heterogeneity, cost recovery, and many others.It is proposed in this research to define and develop the region abstraction and explore its utility as a general mechanism in networking. The research will proceed through several phases of three interrelated activities. The first is the development and definition of the region abstraction itself, with focus on requirements, choice of capabilities, abstract operations, and related issues. The second is designing and building a prototype implementation of the region entity, with focus on appropriate algorithms and adaptation strategies. The third is to examine and validate the region concept through use in three example problems. The examples serve two purposes, to explore the utility of having regions available and to further refine and improve the definition of a region. They are chosen specifically to stress different aspects of the region abstraction.The intention is that the region is a neutral mechanism provided to address many problems, both within a single network layer and across layers. The research will lead to a better understanding of management of multiple layers and the impacts that one can have on another in a controlled way. The research is expected to lead to a framework for decision-making about adaptation to changes in size and usage patterns. Finally, the research is expected to provide a better understanding in each of the example areas of the problems that arise there and how to address them.