臺灣博碩士論文加值系統

目前的網際網路上使用的TCP通訊協定，提供Connection-Oriented、點
對點、可靠的的資料傳輸。廣為使用在全球資訊網、檔案傳輸、遠端登錄一
類的應用程式中。但是TCP無法滿足目前出現的一些新的應用程式如分散式
運算、線上新聞廣播等多向傳輸的服務需求。我們需要一通用的多向傳輸的
傳輸層通訊協定。
因此我們提出了一套可靠（reliable）的多向傳輸式（multicast）傳輸層
（transport layer）通訊協定，名叫MTCP。MTCP提供connection-oriented， 一
個傳送端對多個接收端，依序(sequenced)無漏失(lossless)的資料傳輸服務。對
接收端接收資料的速率最佳化，同時兼顧傳送端的效率。我們使用了數種機
制來達到此一設計目標：negative acknowledgment、destination grouping、
multi-window flow control以及傳送端與接收端定期交換控制封包等。
在MTCP中，傳送端依照各個接收端的接收能力，分為數個群組，對每
個群組各維護一個傳送窗，分別作流量控制。以達到個別接收效能的最佳化。
接收端傳回給傳送端NACK而不是ACK，指示想要重傳的封包，以減少傳
送端接收處理的的封包數目，避免acknowledgment implosion。並引入Era的
封包重傳概念，以減少同一資料重複傳送的次數。接收端與傳送端定期傳送
SR與RR控制封包，以更能有效的追蹤接收端的接收狀況。
我們用軟體模擬MTCP的運作。研究接收端分組、Era的長度、SR、RR、
NACK重傳的間隔對於MTCP的效能的影響。

This paper presents the design of a reliable, connection-oriented multicast
transport layer protocol called Multicast Transmission Control Protocol (MTCP).
MTCP provides sequenced lossless delivery of data from one sender to multiple
receivers. It operates in the Internet, a heterogeneous network composed of
different receivers with diverse data transfer capacity, and assumes the use of
Internet IP multicast service. It maximize the receiving data rate of
individual receivers, and minimize the overhead of the sender. Several features
are used to achieve these design goals: destination grouping, multi-window flow
control, packet pre-buffering, negative acknowledgment and Era-based packet
retransmission, periodic transmission of sender report and receiver report
packets between sender and receivers to keep track of how well receivers are
receiving data.
We also present some simulation result of MTCP with receivers located at
various sites of Internet, and discuss the impact of destination grouping, Era
length, SR, RR, NACK retransmission frequency on the MTCP performance.