Mediacommunication Based on Application-Layer Multi-cast

Abstract

Collaborating and media-handling applications demand efficient and scalable methods for media streaming and group communication; however, such mechanisms have still not been deployed widely in the Internet. Network-level multicasting (in the Internet it is called IP-multicast) gives a bandwidth-saving solution for the one-to-many and many-to-many group communication, since it provides an efficient network mechanism through which senders can transmit their information to a large number of receivers without having to send multiple copies of the same data over a physical link (Hosszú, 2001). The IP-multicast has been realized for research purposes on multicast-capable networks (so-called multicast islands) within the Internet, but wide-scale deployment has not been reached due to some unresolved issues. That is why recent efforts are in the development of multicasting protocols at the application layer instead of the network layer. Most of these Application-Layer Multicast (ALM) protocols address the case of a single-source streaming media to a large number of receivers in applications such as video on demand or live broadcast. In the following sections, the main properties of the ALM protocols are overviewed, then some typical ALM solutions and a new approach are presented.