文章首先讨论了在以太网无源光网络(EPON)系统上实现组播的现实意义，然后在对现有的二层组播协议分析与比较的基础上,提出采用IGMP Snooping(英特网组管理协议侦听)在EPON上实现组播，并结合EPON自身的特点，提出了实现方案 ，最后详细描述了光线路终端(OLT)和光网络单元(ONU)是如何支持IP组播业务的。

This paper first discusses the practical significance of implementing multicasting in EPON systems and then presents a scheme for achieving this goal by adopting IGMP Snooping on the basis of analysis and comparison of the existing layer two (L2) multicasting protocols and in connection with the characteristics of EPON itself. Finally, it explains in detail how OLT and ONU support the IP multicasting services.