Multicasting layered multimedia streams in an ATM environment

HMC (Heterogeneous MultiCast) is a communication paradigm which uses the technique of partitioning data streams into a hierarchy of layers (one base layer and several enhancement layers) and allows each receiver in a multicast connection to subscribe to a different number of layers, based on the available resources and preferences. This paper describes an implementation of HMC over ATM networks. UNI signaling is used as the basic mechanism to create and delete VCs which carry each layer of a hierarchically encoded stream. However, UNI signaling does not provide any means to group the VCs carrying related data from different layers of a particular stream. Grouping of layers is important from an application´s perspective because it expects to receive layers in order (base layer and then the first enhancement layer and so on). One approach to solve this problem is to add intelligence to all the network switches so that they can understand the hierarchy of layers and thus make informed decisions about routing and resource allocation. However, this approach requires changing the switching software throughout the network and hence is not portable. The scheme described in this paper utilizes the existing ATM UNI signaling (which does not have any provision for carrying layered streams) and adds some end-to-end functionality to transport layered streams though a network