由於點對點網路的低成本及易於建置，在這之上提供多媒體串流服務，已經成為近幾年網路研究中受到注目的焦點。多數現存的系統採用應用層群播樹當作底層網路轉傳時的架構，然而，多媒體串流傳輸時所需的高頻寬要求，節點的能力的異質性及不穩定狀態，使得以樹狀為基礎架構的系統產生潛在的效能瓶頸。另外，要求樹狀拓樸系統去支援“類錄放影機”的功能 （如：重複播放或是快轉至影片某一特定播放點），將會使得系統在設計上更加地複雜。
在這篇論文中，我們提出了一個新的系統架構。這個系統架設在階層式網狀的點對點網路上，稱之為HMVOD（Hierarchical Meshed Video-On-Demand System）。使用網狀的拓樸架構有效率地減輕使用頻寬碎裂（bandwidth-leak）的問題，以提升頻寬的使用率，而節點的快取容量的限制，將系統切割成階層式架構。同時，我們使用目錄伺服器來維護階層，並有效率地處理節點在系統上的加入及離開。此外我們還設計了快速重新取得串流區塊來源的機制，以降低離開系統的節點對效能的影響。
我們的模擬結果顯示，我們的系統比起應用層群播樹架構來說，不論是在一般正常播放的模式之下，或者是在類錄放影機播放的模式之下，都可以有效地降低伺服器的負荷量。另外，結果也說明，在頻寬充裕的環境中，我們系統的表現優於應用層群播樹的程度上會更加明顯。

Peer-to-Peer based streaming service has been widely addressed in recent years because of its low cost and easy deployment. Most existing streaming systems employ application layer multicast trees as the underlying infrastructure. However, the high bandwidth requirement in streaming applications leads to potential bottlenecks in the tree-based topology. Moreover, VCR-like operations further complicates the implementation of the tree-based systems. In this paper, we proposed a novel P2P architecture based on a hierarchical meshed topology, called HMVOD. Meshed topology effectively lightens the bandwidth-leak problem and increases the system capacity. Meanwhile, HMVOD maintains a directory server for the hierarchical system which deals with peer dynamics and efficiently provides Video-On-Demand (VOD) streaming services. Besides, we propose fast bandwidth recovery methods for peer departure to prevent from ripply influencing on all the descendants of the leaved peers. Simulation results show that our system reduces server loads and efficiently utilizes peer bandwidth in comparison to application layer tree systems in both normal and VCR-like playback modes.

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