I've covered some of the basic elements of Multicasting, such as IGMP and the Layer 2 switching components in my previous posts (Part 2). This article will go into the technology behind Multicasts at Layer 3 and some of the issues limiting wider use of Multicast technology.
As you recall in my first post, I observed that Yahoo's transmissions of live NHL games would seem to be good candidates for Multicast, yet were being sent as unicast. Then I covered the simple issue of enabling Multicast within a local area network. Coming full circle, here we are diving into Multicast technology to understand why it isn't more widespread.