The most common transmission scheme used in networks today is unicast, which represents "one-to-one" transmission with one sender and one receiver. Sometimes there is a need for one host to send packets that are received by multiple hosts. The problem with implementing this kind of transmission using unicast is that the stream of packets must be replicated as many times as there are receivers. IP Multicast addresses the problem by intelligently sending only one stream of packets and then replicating the stream when it reaches the target domain that includes multiple receivers or reaches a necessary bifurcation point leading to different receiver domains. In this IBM® Redpapers™ publication, we introduce principles of IP Multicast and describe the IPv4 addressing used for multicast. We discuss the protocols that are used to implement multicast in an IP network and then provide the general IP Multicast configuration procedures and then presents IP Multicast configuration in a sample network using IBM System Networking Ethernet Switches. We conclude this paper with command references that include all commands and their parameters for configuration of multicast protocols and features. After understanding the basics of how to configure IP Multicast for the networking scenario described in this paper, IT network professionals will be able replicate a similar design and configuration to suit their network infrastructure.
