Telecommunication Systems 17:3, 299–321, 2001  2001 Kluwer Academic Publishers. Manufactured in The Netherlands. A Multicast Tree Construction Algorithm for Large Multiparty Conferences PAUL JUELL juell@plains.nodak.edu North Dakota State University, Fargo, ND 58102, USA DANIEL BREKKE brekke@mnstate.edu Minnesota State University Moorhead, Moorhead, MN 56563, USA RON VETTER vetterr@uncwil.edu University of North Carolina-Wilmington, Wilmington, NC 28403, USA Abstract. This paper introduces the Multiple Distribution Point (MDP) approach to the construction of multicast trees in computer networks. The MDP approach focuses on the creation of multicast trees for large multiparty conference situations where a high percentage (possibly all) of the participants wish to source multicast data. For certain evaluation criteria, the MDP algorithm is shown to perform better than existing multicast tree construction methods. Keywords: multicast algorithms, videoconferencing, distance education, performance evaluation 1. Introduction The provision of multipoint connections is one of the most important services that will be required in future broadband communication networks which support distributed mul- timedia applications. Multimedia videoconferencing applications, for example, require that both audio and video be transmitted to multiple conference participants simulta- neously. Such group-based communication requires an efficient multicast capability be provided by the underlying network. In order to establish multicast connections between group members, it is necessary to construct a collection of communication channels spanning the network nodes on which the members of the group reside. These communication channels are referred to as multicast trees. Although many generic algorithms have been developed for this purpose, their focus has not been on the creation of multicast trees for large multiparty conference situations where a high percentage (possibly all) of the participants wish to source data. Multicasting has been available on subnetworks for some time. However, not until recently has multicasting been available on the Internet because multicast data had not been allowed to cross network boundaries. If multicast data were allowed to hop from network to network without careful control, the Internet would quickly become satu- rated. IP (Internet Protocol) multicast addressing was developed by Steve Deering in