Source Routing, currently facilitated by Segment Routing (SR), enables precise control of forwarding paths by specifying detours (or segments) to deviate IP packets along routes with advanced properties beyond typical shortest IGP paths. Computing the desired optimal segment lists, known as encoding, leads to interesting challenges as the number of detours is tightly constrained for hardware performance. Existing solutions either lack generality, correctness, optimality, or practical computing efficiency-in particular for sparse realistic networks. In this paper, we address all such challenges with GOFOR-SR. Our framework extends usual path computation algorithms to inherently look at optimal and feasible segment lists, streamlining the deployment of TE-compliant paths. By integrating encoding within the path computation itself and modifying the distance comparison method, GOFOR allows algorithms with various optimization objectives to efficiently compute optimal segment lists. Despite the loss of substructure optimality induced by SR, GOFOR proves particularly efficient, inducing only a linear overhead at worst. It also offers different strategies and path diversity options for intricate TE-aware loadbalancing. We formally prove the correctness and optimality of GOFOR, implement our framework for various practical usecases, and demonstrate its performance and benefits on both real and challenging topologies.

翻译：源路由（目前通过分段路由（SR）实现）通过指定绕行路径（或称分段），使IP数据包能够沿具备超越典型最短IGP路径的高级特性的路由进行转发，从而实现对转发路径的精确控制。计算所需的最优分段列表（即编码）是一项充满挑战的任务，因为绕行路径数量受到硬件性能的严格约束。现有解决方案在通用性、正确性、最优性或实际计算效率方面存在不足——尤其是在稀疏的真实网络环境中。本文提出的GOFOR-SR框架解决了上述所有挑战。该框架扩展了常规路径计算算法，使其能够内在地搜索最优且可行的分段列表，从而简化流量工程合规路径的部署。通过将编码过程融入路径计算本身，并改进距离比较方法，GOFOR支持采用不同优化目标的算法高效计算最优分段列表。尽管分段路由破坏了子结构最优性，但GOFOR仍展现出极高效率——最坏情况下仅引入线性开销。该框架还提供针对复杂流量工程感知负载均衡的多重策略与路径多样性选项。我们正式证明了GOFOR的正确性与最优性，针对多种实际用例实现了该框架，并在真实与挑战性拓扑中验证了其性能与优势。