Real-time transport for assured forwarding: an architecture for both unicast and multicast applications

This paper presents a summary of our work on developing an architecture for transporting real-time traffic (MPEG4 video in this paper) in IP networks that provide service differentiation. We target our architecture at assured forwarding (AF) style services. This architecture assumes loss differentiation in the network and the network's ability to provide ECN messages to the sender. We did not consider policing/shaping at the edge routers. Rather we considered a more general case where marking and flow control are provided at the senders. For this network model, we developed a rate adaptation algorithm that can operate in both unicast and multicast applications with a minor modification. The simulation results presented in this paper represent the multicast case. The results show how the rate adaptation algorithm accommodates different receivers with different networking capabilities and provides them with different qualities by taking advantage of the queue management capabilities of the AF service. We also show the results of testing this architecture with different AF queuing mechanisms, namely RIO and WRED.