非同步傳輸模式交換系統中多點傳播之研究與效能分析

Abstract

在寬頻整合服務數位網路(B-ISDN)中，ATM已被視為混和資料傳輸的未來 趨勢。對於多媒體資料而言，ATM交換系統必須提供多點和點對點的傳播 。 複製網路(copy network)是一種傳統的 多點傳播交換架構。在輕微至中等的訊務負荷下，它能夠讓多點傳播的封 包(cell)維持在低的延遲時間。然而在較重的負荷下，這些封包的延遲時 間會變的很大。因此，我們提出一種較有效率的多點傳播交換架構來克服 上述的問題。這個所提出的架構包含一個複製網路和一個多點傳播的佇列 。這個佇列是用來處理需要較多複製的多點傳播的封包。 為了比較各種 多點傳播交換架構的效能，我們建構了一個獨一的訊務之模型(model)。 我們研究各種的多點傳播架構並且比較它們的效能。然後，以這些架構為 基礎來定義我們所提的架構。藉著使用相同的訊務模型，我們模擬出各種 不同的多點傳播交換架構和我們所提出的架構。之後，以這些模擬結果的 分析為基礎，我們提出一個設計的改進方法。 Asynchronous Transfer Mode (ATM) has been considered as the future trend for the information transfer of mixed traffic carried in the Broadband Integrated Service Digital Network (BISDN). Regarding the multimedia traffic, its point-to- multipoint transfer must be supported by ATM switches as with point-to-point transfer. Copy network is a traditional multicast switch architecture that maintains low multicast cell delay under low to medium load, while under high load the multicast cell delay in the copy network will grow drastically. Here we propose an efficient multicast switch architecture to overcome the above deficiency. The proposed architecture consists of a copy network and an additional multicast queue which processes those multicast cells with large number of copies. In order to compare theperformance of various multicast switch architectures, we construct a unique traffic model. Various multicast switches are investigated and their corresponding performance are compared. Based on these architectures, our proposed architecture is constructed. By using the same traffic model, we perform the simulation to evaluate the performance of different multicast architectures, including ours, and design criteria are suggested based on the analysis of the results.