| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 85 ===
The most existing network applications are developed in TCP/IP network. If the TCP/IP stack can directly sit top of the ATM network and access ATM transparently, we can significantly reduce the time of development and efforts to import the network applications into the ATM environment. Therefore, the benefits of the broadband service will be utilized immediately.
Nevertheless, It is indicated that the effective throughput of TCP over plain ATM without any ATM-level traffic control will tremendously degrade when an ATM network is in congestion. Thus, many researches study the TCP/IP over ABR and improve the performance of TCP/IP over ATM.
In this thesis, we do not only study the performance of TCP/IP over ABR in the ATM network but also propose the two mechanisms to enhance the performance of TCP/IP over ABR. One is "shortening retransmission time mechanism" and another is "window size estimation mechanism". The former can overcome the drawback of TCP retransmission mechanism to shorten the waiting time of time-out. The latter calculate the virtual channel capacity from the information in ABR to estimate a proper transmission window size for each TCP source. This can avoid congestion and improve the end-to-end throughput.
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