多媒體多點傳播在ATM網路上之模擬與效能分析

Abstract

隨著寬頻整體服務數位網路技術和數位影像壓縮技術之進步，及時性多媒 體服務也愈來愈普遍。多媒體資料的特性之一為資料量非常大，尤其是視 訊與音訊，所以必須將資料量壓縮。除了資料量龐大之外，多媒體資料也 具有延遲時間的限制，包括end-to-end delay 及 jitter delay。為了支 援視訊與音訊的龐大資料量及嚴格的延遲時間限制，一個適用多媒體資料 的多點傳播方法是必須的。因此，在這篇論文中，我們提出了一個適用於 多媒體資料的多點傳播方法。在這篇論文中，模擬系統採取社區共同天線 （CATV）式的服務架構，網路系統則為 ATM LAN。首先將比較分散式伺服 器與集中式伺服器的效能。然後分析在分散式伺服器的架構下，所提出的 方法與其它方法的優劣比較及效能分析。最後，我們比較所提出的多點傳 播方法在使用不同架構之多點傳播交換系統下，所能表現的效能並說明不 同交換系統之多點傳播的優缺點。最後，我們將討論電腦模擬的結果，分 析其效能並做優劣點之評估。 The rapid advancement of networking technology of Broadband ISDN and digital video coding techniques makes the real- time multimedia services more and more popular. Multimedia data has the feature that the data volume is extremely large especially for video and audio, so the compression of data is necessary. In addition to high data volume, multimedia data also has the delay constraints including end-to-end delay and jitter delay. In order to support the high data rates and stringent delay constraints for video and audio applications, a good multi- casting algorithm dedicated for multimedia is necessary. As a result, a multicasting algorithm is proposed for multimedia applications in this paper. In this thesis, the simulation system attempts to model the CATV services, and the network configuration is an ATM LAN. First we will show the performance comparison of distributed servers and centralized servers. And then the performance evalu- ation of our proposed algorithm and the end- to-end delay optimi- zation algorithm under the system using distributed servers is given, finally the simulation results of our proposed algorithm using two different multicast switch architectures, i.e. shared bus and copy network, are compared. At last, we discuss the simulation results, and we analyze the performance as well as evaluate the pros and cons of the system.