A Space Internet is possible, as long as the delay and disruption challenges imposed by the space environment are properly tackled. Because these conditions are not well addressed by terrestrial Internet, more capable Delay-Tolerant Networking (DTN) protocols and algorithms are being developed. In particular, the principles and techniques for routing among ground elements and spacecraft in near-Earth orbit and deep-space are enacted in the Contact Graph Routing (CGR) framework. CGR blends a set of non-trivial algorithm adaptations, space operations concepts, time-dynamic scheduling, and specific graph models. The complexity of that framework suggests a need for a focused discussion to facilitate its direct and correct apprehension. To this end, we present an in-depth tutorial that collects and organizes first-hand experience on researching, developing, implementing, and standardizing CGR. Content is laid out in a structure that considers the planning, route search and management, and forwarding phases bridging ground and space domains. We rely on intuitive graphical examples, supporting code material, and references to flight-grade CGR implementations details where pertinent. We hope this tutorial will serve as a valuable resource for engineers and that researchers can also apply the insights presented here to topics in DTN research.

只要延迟和中断，就有可能使用太空互联网适当应对空间环境带来的挑战。由于地面Internet无法很好地解决这些条件，因此正在开发功能更强大的延迟容忍网络（DTN）协议和算法。特别是，在“接触图路由”（CGR）框架中制定了在近地轨道和深空中地面要素和航天器之间路由的原理和技术。CGR融合了一组非平凡的算法改编，空间操作概念，时间动态调度和特定的图形模型。该框架的复杂性表明需要进行有针对性的讨论，以促进其直接和正确的理解。为此，我们提供了一个深入的教程，该教程收集和组织了有关CGR研究，开发，实施和标准化的第一手经验。内容的布局结构考虑了规划，路线搜索和管理以及桥接地面和空间域的转发阶段。我们依赖于直观的图形示例，支持的代码材料，以及在适当时引用飞行级CGR实施细节的参考。我们希望本教程将为工程师提供宝贵的资源，并且研究人员也可以将此处介绍的见解应用于DTN研究中的主题。