Multicast, a multipoint communication model in the networking realm, is an efficient way to send multiple copies of data to different users. Many applications, such as video and audio conferencing, can benefit from this tool. Because of the diversity of applications, however, the real-time requirements for multicast include quality of service (QoS). This book chapter is a survey of multicasting, focusing on routing algorithms for real-time multimedia applications.

The chapter clearly reviews the multicast concept and the major routing protocols. QoS-based routing algorithms are surveyed, including shortest path tree, minimum spanning tree, and constrained Steiner tree algorithms. All of these QoS routing algorithms try to find a feasible path between the source and the destinations, which are NP-hard problems; the author does not include a complete survey of QoS multicast routing algorithms. Some potential applications of multicasting are also discussed.