疊蓋式多重播送服務 (Overlay Multicast)是一個用來解決傳統的網路層多重播送服務(IP Multicast)會遇到的佈署與延伸性問題的新興方法。如何提升疊蓋式多重播送服務的效能是值得探討的一項重要議題。在此篇論文中，我們提出了一個基於疊蓋式網路且具有拓樸導向、負載平衡與路徑分岐性高等特性的等級制度多獨立樹多重傳播機制。若與傳統方法比較，用此機制所建立出來的多重播送樹有節點不交集與路徑不交集的特性，意即每顆樹中包含的非樹葉節點不相同，每顆樹中所包含的路徑亦不相同。所以，每一個節點只負責傳送資料一次且每份資料所經過的路徑皆不相同。如此一來，當有任何節點或路徑發生問題時，最多只會影響到包含此節點或路徑的多重傳播樹，進而提升整個系統的服務品質。此外，在此機制中多重傳播樹的建立是基於完整k元樹，如此一來，可以控制使每個節點負責傳送的資料份數，進而保証負載平衡的特性。由模擬的結果可以看出，我們所提出來的方法是一個具有可信賴、高效率且負載平衡等特性的機制。

An overlay multicast is proposed to solve the scalability and deployment problems in IP Multicast. We propose a scheme, Topology-oriented Load-balance Hierarchical Independent Tree (TLHIT), with topology-oriented, load-balance and path diversity properties to improve the performance of overlay multicast. Compared to traditional methods, the proposed TLHIT constructs not only node-disjoint but also path-disjoint multicast trees where each node serves as an interior node in only one tree and different trees do not contain the same path. Moreover, TLHIT ensures load-balance property by building the multicast trees based on n-ary full tree. It ensures that each node serves almost the same amount of child nodes. Simulation results show that the reliability, efficiency, and load-balance properties of the proposed TLHIT are assured.

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