Because of the planarity and diversity of multimedia, and the increasing rate of wireless network popularity, the sharing and exchanging actions among different users are common. 由于多媒体资料的丰富性和多样性，以及无线网路普及率节节升高，多媒体资料在不同使用者之间的分享与交换行为日益普遍。
Multicasting is an efficient way to send a stream of multimedia data to many users on a shared-media hub.However, it affects every user on a flat switched network. 群播是发送多媒体资料流给在共享媒体集线器上的许多使用者的一种有效率的方式，然而，它影响在扁平交换网路上的每个使用者。
