Core-Based Trees is a proposal for making IP Multicast

IP Multicast

IP multicast is a method of sending Internet Protocol datagrams to a group of interested receivers in a single transmission. It is often employed for streaming media applications on the Internet and private networks. The method is the IP-specific version of the general concept of multicast...

 scalable by constructing a tree

Tree structure

A tree structure is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree, even though the chart is generally upside down compared to an actual tree, with the "root" at the top and the...

 of routers. It was first proposed in a paper by Ballardie, Francis, and Crowcroft. What differentiates it from other schemes for multicasting is that the routing tree comprises multiple "cores" (also known as "centres"). The locations of the core routers are statically configured. Other routers are added by growing "branches" of a tree, comprising a chain of routers, from the core routers out towards the routers directly adjacent to the multicast group members.