A paradigm shift in the distribution of multimedia

M ultimedia blends two or more media together, such as text, graphics, sound, or movies. The Internet, home to multimedia for quite some time, has been stymied by the transmission requirements of multimedia partnerships. Indeed, audio and video often require several megabytes to work in tandem, thus taking a great deal of time to transmit. For this reason, their availability has been sharply limited for most users. Multimedia works best as an interactive endeavor, but for the most part, Internet multimedia is not interactive; it’s click and wait. The intertwining of multimedia and the Internet makes sense. People prefer multimedia on their desktops. It’s engaging, entertaining, and makes otherwise complex systems a little easier to use and understand. Traditionally, much of the information sent over the Internet has a specific destination, such as an email message sent to a specific colleague. A request for a Web page is transmitted to a single host, and the host sends back the requested information to the single recipient. Although computers can handle a substantial number of these requests every second, the information is basically one-to-one: One computer sending the information and only one receiving it. This arrangement seems fine until we wish to send information simultaneously to more than one person. IP multicast supports this type of transmission efficiently by enabling sources to send a single copy of a message to multiple recipients who explicitly want to receive the information [7]. This is far more efficient than requiring the source to send an individual copy of a message to each requester (point-to-point unicast), in which case the number of receivers is limited by the bandwidth available to the sender. It is also more efficient than broadcasting one copy of the message to all nodes (broadcast) on the network, since many nodes may not want the message, and because broadcasts are limited to a single subnet. IP multicast is an extension to the standard IP network-level protocol. IP multicasting is the transmission of an IP datagram to a host group, a Gerard Parr and Kevin Curran