SHF: Small: A Versatile, Adaptive Network Architecture for Combating Traffic Heterogeneity in Data Centers

在技术进步的推动下，大型在线服务提供商已经建立了由数万甚至数十万台服务器组成的大型数据中心作为基础设施，其中数据中心网络的性能起着关键作用。数据中心网络（DCN）中的流量通常在网络中的不同位置、各种应用之间、不同公司的实现之间以及不时地表现出巨大的异构特性。另一方面，当今的数据中心网络仍然缺乏足够的灵活性来以有效的方式处理如此巨大的异构流量。同时，随着虚拟化技术的深入发展，云应用程序并不直接运行在物理硬件或操作系统上。相反，它们被分配在从底层网络虚拟化的模拟操作系统层上。因此，单个基础设施提供商可以为不同的用户支持许多虚拟机/网络，同时使每个用户保持整个基础设施被该用户唯一占用的愿景。为了应对这些挑战，本研究设计了一个通用的网络架构，面向不断增长的性能需求和异构流量的特点，今天的数据中心。该架构提供了一个自适应的全栈范例，其中包括互连拓扑，寻址和路由方案，以及虚拟化算法。具体而言，本文的研究重点是以下几个紧密耦合的问题：（1）设计一种新的、经济高效的DCN体系结构，能够动态、系统地处理数据中心中的业务异构性：（2）在单播和多播业务模型下，设计相应的路由算法;（3）在体系结构中开发有效的网络虚拟化算法，包括虚拟网络嵌入，在地理上分布的DCN上的虚拟网络功能放置和虚拟化;（4）通过在现实网络原型中对方案进行广泛的模拟和实现来进行综合性能评估。该研究结合了理论分析，算法设计，网络优化，仿真和原型技术，提供了一个全面的工作解决方案，使高性能的下一代DCN。这项研究有望对未来DCN的基本设计原则产生深远的影响。这项研究的成果不仅将大大提高DCN的灵活性和能源效率，同时保持低成本，而且还将促进目前托管在数据中心的众多云计算应用程序。随着云计算渗透到社会的各个方面，这项研究将对社会产生更广泛的影响，并有助于改变世界。

Driven by technology advances, massive data centers consisting of tens or even hundreds of thousands servers have been built as infrastructures by large online service providers, in which the performance of data center networks plays a critical role. Traffic in data center networks (DCNs) generally exhibits tremendous heterogeneous characteristics, at different locations in the network, among various applications, between distinct companyís implementations, and from time to time. On the other hand, today's data center networks still lack sufficient flexibility to handle such huge heterogeneity of traffic in an efficient way. Meanwhile, as virtualization techniques undergo a profound development, cloud applications do not directly run on physical hardware or operating systems. Instead, they are assigned on a simulated operating system layer which is virtualized from a substrate network. Thus, a single infrastructure provider can support numerous virtual machines/networks for different users while keeping each user with a vision that the entire infrastructure is uniquely occupied by the user. To meet the challenges, this research designs a versatile network architecture oriented to the ever-increasing performance demands and heterogeneous traffic characteristics of today's data centers. The architecture provides an adaptive full-stack paradigm which includes interconnect topologies, addressing and routing schemes, and virtualization algorithms. More specifically, the research focuses on several closely coupled issues: (1) design a novel, cost-efficient DCN architecture that can dynamically and systematically handle traffic heterogeneity in data centers; (2) design the corresponding routing algorithms for the architecture under unicast and multicast traffic models; (3) develop efficient network virtualization algorithms in the architecture, including virtual network embedding, virtual network function placement and virtualization over geographically distributed DCNs; (4) conduct a comprehensive performance evaluation through extensive simulations and implementation of the schemes in a realistic network prototype. The research combines theoretical analysis, algorithm design, network optimization, simulation and prototyping techniques to provide a comprehensive working solution that enables high performance next generation DCNs. This research is expected have a profound impact on fundamental design principles of future DCNs. The outcome of this research will not only greatly boost the performance of DCN flexibility and energy efficiency while keeping low cost, but also facilitate numerous cloud computing applications currently hosted in data centers. As cloud computing is penetrating into all aspects of the society, this research will have a broader impact on the society and help change the world.