A Fundamental Study on Quantitative Methods for Constructing Light-Weight Protocols in High-Speed Networks

点击翻译按钮获取中文摘要

The research results obtained here can be classified into four categories. The first is concerned with performance evaluation of high-speed MAC protocols, which is necessary for studies on end-to-end light-weight protocols. We analyze DQDB and slotted rings by means of the equilibrium point analysis (EPA). The throughput and average packet delay are evaluated for finite-buffered users.The second result is analytical performance modeling of two-layr protocols which consists of a high-speed MAC and a light-weight LLC protocols. The LLC protocol, which is referred to as Fast Select Connection-Oriented (FS-CO), is also regarded as an end-to-end protocol for a single layr into which LLC, network and transport layrs are integrated ; it establishes and releases connections implicitly. As the MAC protocol, we choose TDMA-Reservation for satellite networks and slotted ring for LAN's. It is shown by EPA that the FS-CO outperforms conventional protocols over a wide range of traffic condition.Thirdly, we study rate-based flow control chemes, which is efficient in high-speed networks. The schemes dynamically change the transmission rate (inter-packet gaps) depending on the packet queue length in the buffer of the distination node. We set one or more threshold values for the queue length. If the length exceeds or falls below one of the threshold values, then the destination node sends a control packet back to the source node to adjust the transmission rate. the performance of the schemes is evaluated through simulation for time-varying traflic.Lastly, we measure message delay time in an FDDI LAN under the TCP and UDP protocols. This measurement is taken for the prupose of evaluating overheads of the existing transport protocols. The data thus obtained are useful in designing light-weight end-to-end protocols.