近幾年來由於網際網路與多媒體應用程式的蓬勃發展，使用者對於網路頻寬的需求與日俱增，群播式多媒體網路服務的興起更為新一代的網路環境帶來了全新的面貌。在光纖網路上，藉由高密度光波分工技術，單一光纖鏈結的頻寬得到了大幅度地提升，然而傳統的光通道卻有頻寬利用率低落的缺點。此外光通道對於快速動態提供連線以及支援群播技術的能力亦不純熟，漸漸地無法滿足新一代的網路服務趨勢。相較於光通道，光曳帶網路架構可以快速地建立多組連線且不需負擔光訊號交換所帶來的額外成本，自提出後便被視為是一個能有效運用高密度光波分工網路頻寬的傳輸架構。藉由支援子波長粒度，光曳帶能有效地提升單一波長的頻寬利用度。最重要的是，光曳帶與生俱來便有支援群播的優點。進一步考慮資料能在任意節點上由一個光曳帶聚合至另一個光曳帶，光曳帶儼然成為支援新一代群播式多粒度頻寬需求之光網路的主要考量。

在本篇論文中，我們提出了一個在光曳帶網路上結合群播技術與流量聚合的動態群播繞徑演算法，稱為以光曳帶為基礎之群播繞徑演算法。針對靜態網路，我們提出了一組整數線性規畫公式以求得群播繞徑問題之最佳解。在動態網路方面，藉由在輔助圖模型上準確地標示出網路資源的分佈與狀態，我們可以更有效率地為群播要求進行路徑選取。在模擬實驗中，我們使用不同的網路拓樸與資源的參數設定以分析本篇論文所提出的方法，實驗得到的結果驗證了我們所設計的演算法所得到的結果能近似於最佳解，並且能夠充分的發揮光曳帶網路本身的特點。相較於過去文獻中提出的動態繞徑演算法，我們的方法可以大幅改善阻斷機率的表現。我們也驗證了光曳帶網路確實能夠支援現今多粒度動態頻寬需求與群播的網路環境。

In recent years, because of the popularity of Internet and the rapid growth of multimedia applications, the requirements of bandwidth from users increase violently in optical networks. The variant multicast multimedia service also brings to the big challenges for next generation optical networks. As the rapid advance of DWDM, the bandwidth of a single fiber link is significantly improved. However, the traditional circuit switching architecture, lightpath, has the disadvantage with lower bandwidth utilization of a single wavelength. Besides, lightpath is not mature of fast provisioning for connections as well as the multicast property. Lightpath is seemed to become insufficient for the web service of next generation networks. Light-trail has been proposed as an efficient solution to support optical networks today. Compare with lightpath, a light-trail can establish multiple connections fast without optical switching. The support of sub-wavelength granularity in light-trial network increases the utilization of wavelength bandwidth effectively. The most important thing is that light-trail allows multiple node access the transmission channel. In a light-trail, the single send by one node will be received by the downstream nodes. In other words, light-trail has the advantage of natural multicasting. Further, if we take the property that the traffic can be groomed from one light-trail to other light-trails at any nodes into consideration; the light-trail obviously becomes a strong candidate to support the multicast and the multi-granularity bandwidth demands in the future networks.

In this thesis, we propose a dynamic multicast routing algorithm with traffic grooming consideration in light-trail networks, named Dynamic Light-Trail-based Multicast Routing algorithm (DLTMR). For the static networks, we propose a set of ILP formulations to calculate the optimal solution for minimizing the number of established light-trails. In the dynamic networks, we can efficiently find a best route for each multicast request by using DLTMR. In the simulation, we use different network topologies and the variant limitation of network resource to verify that DLTMR can efficiently improve blocking performance in the light-trail networks. On the other hand, we also verify that the light-trails are suitable to support the multi-granularity bandwidth demand and multicasting.

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