Fixed and mobile telecom operators, enterprise network operators and cloud providers strive to face the challenging demands coming from the evolution of IP networks (e.g. huge bandwidth requirements, integration of billions of devices and millions of services in the cloud). Proposed in the early 2010's, the Segment Routing (SR) architecture helps facing these challenging demands and it is being adopted and deployed. The SR architecture is based on the concept of source routing and has interesting scalability properties as it dramatically reduces the amount of state information to be configured in the core nodes to support complex services. The SR architecture has been first implemented with the MPLS dataplane and then, quite recently, with the IPv6 dataplane (SRv6). In this paper we present a tutorial and a comprehensive survey on the SR technology, analyzing research activities, standardization efforts and implementation results. We start with an introduction on the motivations for Segment Routing and an overview of its evolution and standardization. Then, we provide a tutorial on the Segment Routing technology, with focus on the novel SRv6 solution. Next, we thoroughly analyze the research activities according to a taxonomy. We have identified 7 main categories during our analysis of the current state of the art: Traffic Engineering, Failure Recovery, Centrally Controlled Architectures, Path Encoding, Network Programming and Miscellaneous. We also discuss the standardization efforts, providing details on the most important documents and listing other ongoing activities along with pointers to them. Last but not least, we present the up-to-date status of SR implementation and provide references to several open source projects.

中文翻译：

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Segment Routing：对研究活动、标准化工作和实施结果的综合调查

固定和移动电信运营商、企业网络运营商和云提供商努力应对来自 IP 网络演进的挑战性需求（例如巨大的带宽需求、数十亿设备和数百万服务在云中的集成）。分段路由 (SR) 架构于 2010 年初提出，有助于应对这些具有挑战性的需求，并且正在被采用和部署。SR 架构基于源路由的概念，并且具有有趣的可扩展性属性，因为它极大地减少了在核心节点中配置以支持复杂服务的状态信息量。SR 架构首先是通过 MPLS 数据平面实现的，然后是最近使用 IPv6 数据平面 (SRv6) 实现的。在本文中，我们提供了关于 SR 技术的教程和全面调查，分析了研究活动、标准化工作和实施结果。我们首先介绍 Segment Routing 的动机及其演变和标准化的概述。然后，我们提供有关分段路由技术的教程，重点介绍新颖的 SRv6 解决方案。接下来，我们根据分类法彻底分析研究活动。我们在分析当前最先进技术时确定了 7 个主要类别：流量工程、故障恢复、集中控制架构、路径编码、网络编程和其他。我们还讨论了标准化工作，提供了最重要文件的详细信息，并列出了其他正在进行的活动以及指向它们的指针。