A Pragmatic Semantic Reliable Multicast Architecture for Distant Learning

Although IP multicast has been rapidly evolving in the last few years, the current Internet is not fully multicast-enabled because of the lack of robust inter-domain routing and controlling protocols. In this paper, we present an alternative architecture for data distribution on Internet called PSRM that realizes semantic reliable, loose synchronized, multicast data delivery. PSRM is not based on global IP multicast, instead it uses a hybrid way to combine unicast delivery with multicast delivery. In PSRM, IP multicast is used only in local area, or multicast domain, to enhance the performance, and these multicast domains are organized into a spanning tree by TCP connections. As PSRM is based upon ALF protocol architecture, we use application-defined semantics to adapt content in a heterogeneous environment. PSRM have been implemented and demonstrated by a prototype distance learning application.