Abstract
隨著通訊技術的日新月異與傳輸媒體的演進改良，國際電報電話諮詢 委員會(CCITT)在1984年提出了整體服務數位網路(Integrated Services Digital Network, ISDN)的標準，希望能將現行在不同網路上所提供的通 訊服務整合起來，由單一數位網路來提供服務。然而，隨著通訊服務的多 元化的發展及高傳輸量的需求，ISDN所提供的頻寬已不敷使用，於是又提 出了寬頻整體服務數位網路(Broadband ISDN, BISDN)的建議書來滿足對 頻寬及傳輸效率的要求。國際電報電話諮詢委員會更在1988年明確的定義 出非同步傳輸模式(Asynchronous Transfer Mode, ATM)為製作BISDN的基 本傳輸模式。依據傳輸節點的連結方式，通訊服務可大致分為二大類：點 對點的通訊服務(稱為單一傳輸(unicast))和一點對多點的通訊服務(稱為 多重廣播(multicast))。有許多的通訊服務在本質上便具有一點對多點或 多點對多點的傳輸特性，此類服務又稱為多重廣播(multicast)通訊服務 。例如：電傳會議(teleconferencing)、家庭娛樂視訊(home entertainment video)等。因此，我們須有一個能支援此類服務的多重廣 播交換系統。多重廣播交換的操作由二個基本操作組成：複製( duplication)與傳送(routing)。依此二個基本操作的執行方式，在設計 多重廣播交換系統時，需考慮下列問題：複製演算法、多重廣播群組識別 碼轉換、複製的溢滿控制、複製網路的衝撞解決方法。根據這些設計上所 需考慮的問題，我們提出了四種多重廣播交換架構，其中每一架構的操作 與效率分析均有詳細的敘述。 The significant improvement of communication technique tends to integrate a diversity of services into one universal transmission environment. The developments of the Broadband Integrated Digital Services Network (B-ISDN) are to provide such kind of transport of services with different bandwidth and performance requirements. According to the membership involved in the connection, the transmission services can be simply divided into two categories: point-to-point (referred as unicast) and point-to-multipoint (referred as multicast) services. The researches on unicast switching system have intensively studied in the last decades. To efficiently support the multicast services, the multicast switching system will play an important role in the future communication fields. Multicast services represent the provision of connections that transmit packets from one node to multiple nodes. The tasks performed by the multicast switching system include duplication and routing. According to the ways to perform these two tasks, the multicast switching systems can be classified into two categories: isolated multicast switching system and unified multicast switching system. The main feature of the isolated multicast switching system is distinctively divided the whole multicast operation into copying and routing operations, and both of them are performed by different interconnection networks respectively. Such kinds of multicast switches are of advantages to easily augment the multicasting capability to the unicast switches by appending a copy network in the front of it. On the other hand the unified multicast switches simultaneously perform the copying and routing operations in the same network. The treatments of the incoming cells are in a fair situation. The performance requirements of the multicast services are guaranteed. The isolated multicast switching system can be further divided into two structures: cascaded multicast switching system and multicast module attached switching system. No matter what kind of multicast switching architectures is considered, the design issues involved can be addressed as four aspects: copy algorithms, multicast group number translations, overflow control of duplication, and collision resolution for the copy network. The multicast switching architectures proposed in this dissertation include both kinds of fabrics. The class of isolated multicast switching systems, including the distributed copy network and the dilated multicast Banyan network, are constructed by the idea of partial duplication that divides the entire duplication operation into two sub-copy processes: static copying process and dynamic copying process. This division of duplication process results in reduction of the loss rate and simplification of the maintenance for the multicast connections. On the class of the unified multicast switching system, the broadcast feature of the shared connected bus in the Knockout switch is used to design a multicast switching with the capability of duplication and routing in the same network. The fair treatments of the multicast and unicast cells reduce the delay needed to transmit the multicast ones. At last, we present the other unified multicast switching architecture based on multistage topology in this dissertation and describe the advantages that this kind takes.