仅部分节点具有组播能力的光网络称为稀疏分光网络，基于网络性能和成本的考虑，网络常为稀疏分光配置。稀疏分光网络中组播路由主要解决如何为多点传送的组播业务请求寻找合适的光树或光森林的问题。在综合分类的基础上，文章重点对目前稀疏分光网络中的组播路由机制和相关算法进行分析和总结，并对未来工作进行了展望。

Optical networks with only a portion of their nodes capable of supporting multicast are called sparse splitting optical networks. In consideration of network performance and cost, optical networks are usually configured in a sparse light-splitting state.The multicast routing in these networks mainly aims at requesting to find appropriate light-trees or light-forests for the multipoint transmission of multicast traffic. This paper focuses on analyzing and summarizing the multicast routing mechanism and the relevant algorithms in current sparse splitting optical networks on the basis of integrated classification and forecasting the future work.