A simple and scalable fair bandwidth sharing mechanism for multicast flows

Despite a decade of research and development, multicast has not yet been deployed on a global scale. Among the difficulties with the current infrastructure are inter-multicast fairness support, multicast congestion control, and multicast routing. We focus on the inter-multicast fairness issue which addresses the way how the network resources are shared between competing multicast flows. We propose a simple and scalable single FIFO queue-based active queue management mechanism called MFQ (multicast fair queuing) to achieve the desired inter-multicast fairness. MFQ interacts with an external multicast bandwidth allocation module which implements a pre-defined inter-multicast fairness function. To guarantee a fine-grained packet queuing/dropping, MFQ uses a novel bandwidth sharing notion, called multicast allocation layer (MAL). Based on this notion, MFQ classifies multicast packets into layers and adjusts their weights in order to provide a bandwidth sharing being as close as possible to that given by the fluid model algorithm. Simulation results demonstrate that MFQ achieves the expected allocation for both responsive and non-responsive multicast flows. We validate our findings by analyzing the impact of network and groups dynamics on the expected bandwidth allocation and comparing it to that obtained by MFQ. Furthermore, we show that MFQ converges very fast to a stable state and easily adapts itself to the dynamic change of the flows weights.