Application level multicast with multiple distribution trees is effective for real-time streaming in terms of low delay and jitter. However, failure of upstream nodes drastically influences on the performance of many downstream nodes in multiple tree-based multicast. This degradation of video data continues until reconstruction of distribution trees finishes. Therefore, it is important to recover from the isolation as fast as possible. In this paper, we propose proactive and reactive approaches in order to resolve this problem. The proactive approach realizes fast recovery from isolation and efficient randomized forwarding by distribution trees cooperation. Each node forwards received data to its child nodes not only in the tree but also in other trees according to a pre-determined probability. In contrast, in the reactive approach, an isolated node requests forwarding from other nodes after detecting the parent node's trouble. This approach achieves quick response by requesting to near nodes. Moreover, we propose the hybrid method combining these two approaches. This hybrid method has advantages of both the proactive and reactive approaches. Finally, we evaluate the performances of the proposed methods through computer simulations, and confirm the effectiveness of the proposed methods.
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