CRII: NeTS: Towards a database-defined network

软件定义网络（SDN）为在简化网络实践的过程中运用计算原理提供了前所未有的机会。实际上，许多突出的SDN特性——中央控制和编程接口——是通过编程语言、操作系统和分布式系统领域的原理实现的。虽然这些原则产生了各种编程抽象，极大地改善了网络实践，将复杂的分布式协议简化为更简单的集中式程序，但对于什么是正确的抽象，几乎没有达成共识。此外，今天的网络架构师需要组合异构数据源——网络转发规则、数据流和QoS指标、主机入侵警报等等——以生成网络的内聚视图并调查问题。为了解决具有挑战性的网络抽象和集成问题，该项目将探索数据库的计算原理——这是一个几十年来富有成果的理论和商业成功的原理，但令人惊讶的是，在SDN中还没有得到充分的研究。这个数据库定义的网络项目建立在SDN控制基本上围绕数据表示的观点之上，其中整个SDN网络都在标准SQL数据库的引子下，依靠SQL实现灵活和可扩展的网络抽象，并利用数据库集成技术将多个控制应用程序组合成一个一致的转发行为。为了实现这一雄心勃勃的目标，该项目将首先开发一种新颖的以数据库为中心的控制器平台，以解决经典数据库应用程序中没有的两个独特的网络挑战：(1)系统可扩展性要求，以适应不断扩大的控制应用程序；(2)在复杂的控制应用中应对快速数据平面更新的性能要求。此外，控制器平台将通过数据集成组件进行增强，以管理控制应用程序之间的依赖关系，解决集成控制应用程序的长期问题-将潜在重叠和冲突模块的集合组合成一致的网络转发行为。该项目的结果将产生多个问题的解决方案，包括一种有吸引力的可进化SDN抽象形式和控制应用程序之间的自动协调。所有的抽象和协调功能都将通过广泛熟悉的SQL接口向应用程序程序员、网络工程师和架构师公开。因此，该项目可能在技术上和作为一种鼓励更快地采用SDN的方式上都很有价值。该项目将通过开发研究生水平的“软件定义网络中的计算原理”课程，将本提案的理论研究方法和内容与教育相结合。通过对各种基本方法（如数据库、分布式系统、编程语言）对突出的SDN抽象和集成问题的分析和比较，该项目还将产生一份关于计算原理和SDN的调查报告。

Software-defined networking (SDN) provides an unprecedented opportunity to exercise computing principles in simplifying networking practice. Indeed, many salient SDN features --- central control and programming interfaces --- are enabled by principles from the fields of programming language, operating systems, and distributed systems. While these principles have produced a variety of programming abstractions that drastically improve networking practice, reducing the complex distributed protocols to simpler centralized programs, there is little consensus on what are the right abstractions. Moreover, network architects today need to combine heterogeneous data sources --- network forwarding rules, data flow and QoS metrics, host intrusion alerts, and so on --- to produce a cohesive view of the network and investigate problems. To tackle the challenging network abstraction and integration problem, this project will explore the computing principle --- a principle blessed with decades of fruitful theories and commercial success, yet surprisingly under-investigated in SDN --- of database.This database-defined network project builds on the perspective that SDN control fundamentally revolves around data representation, where the entire SDN network is under the hood of a standard SQL database, relying on SQL for flexible and extensible network abstraction, and leveraging the database integration techniques for combining multiple control applications into a coherent forwarding behavior. In achieving this ambitious goal, this project will first develop a novel database-centered controller platform that address two unique networking challenges not found in classic database applications: (1) the system extensibility requirement to accommodate an enlarging body of control applications; and (2) the performance requirement to cope with very fast data-plane updates under complex control applications. In addition, the controller platform will be enhanced with data integration component to manage dependencies between control applications, addressing the long-standing problem of integrating control applications --- combining a collection of potentially overlapping and conflicting modules into a coherent network forwarding behavior.The results of the project will yield solutions to multiple problems, including an attractive form of evolvable SDN abstractions and automated coordination between controls applications. All the abstractions and coordination facilities will be exposed to application programmers, network engineers and architects via the broadly familiar SQL interfaces. Thus, the project is likely to be valuable both technically and as a way to encourage more rapid uptake of SDN. The project will integrate the theoretically-grounded research methodology and content of this proposal with education by developing a graduate-level 'Computing principles in software-defined networking' course. Informed by the analysis and comparison of the various fundamental approaches (e.g., database, distributed system, programming language) to prominent SDN problems of abstraction and integration, the project will also result in a survey paper on computing principles and SDN.