Internet Protocol Television (IPTV) is a service on the Internet where digital TV signal (data) is delivered to the participants using the Internet Protocol (IP). IPTV promises to provide many TV channels with lower price for operators & consumers and it can be distributed more efficiently to the end user than traditional coaxial cable distribution. As it is assumed that broadband connection of households will grow at a brisk pace, IPTV will play more and more important role in the coming years in our lives. The plenty of TV channels requires large bandwidth for highly clear TV programs in IPTV service which is a contradictory issue to the limitation of user access line bandwidth and aggregation network bandwidth. Multicast is a mature one-to-many packet data delivery technology which can be used for IPTV service necessary to resolve such contradiction. But which one and in which level of network, multicast will be best suited for this emerging technology is still a burning question. In this book we have studied all sorts of multicast protocol for various network level to find out a appropriate multicast solution for IPTV service.