Web Caching and Replication

2.4. Multicast

IP multicast is a mechanism that allows efficient delivery of a datagram to multiple hosts on the Internet. Multicast is useful in situations when many hosts, called a multicast group, are interested in the same content. For example, the Internet video broadcast of the Victoria's Secret fashion show draws hundreds of thousands of users every year. The datagrams sent to the hosts of all those users are, for the most part, identical. The idea behind IP multicast is to optimize the transmission of IP datagrams in such a way that an identical datagram traverses the link between two routers only once. Therefore, multicast is directly relevant to our subject in that it allows the efficient distribution of content to many browsers, proxies, ...