Hierarchical architecture for real time causal delivery

The evolution of communication technology makes possible distributed real-time multimedia applications. Unlike traditional data traffic, real-time multimedia traffic requires that temporal relationships among media units must be maintained, and needs that all sites impose a consistent causal order to receive the same media at a given time. Yet delay jitter, the absence of a global clock, and a crash failure may disrupt these temporal relationships. This paper proposes new hierarchical architecture of k-local groups, where k represents the number of local groups composing the group communication system. This architecture ensures real-time causal ordering and guarantees an automatic reconfiguration, in presence of a crash failure, by ensuring at least a partial real-time communication between active local groups, while keeping the amount of control information within a reasonable size.