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We present Dagster, an end-host multicast scheme for delivering multimedia streams. Unlike previous schemes, Dagster does not constrain the amount of bandwidth a node must donate. Instead, it relies on a novel incentive scheme to encourage nodes to contribute more bandwidth to improve the total capacity of the system. The key idea behind the incentive is that Dagster allows a node with more donated bandwidth to preempt another node in the system. Dagster also allows a host to receive from multiple parents at the same time, thus is more resilient to node failures. Our simulation results show that Dagster's design leads to low rejection rate, high resilience to failure and smaller diameter. Furthermore, nodes that donate more bandwidth have lower rejection rate and are positioned fewer overlay hops away from the source, providing incentives for nodes to increase their contribution.