UBC Theses and Dissertations
Performance evaluation and comparison of a token ring network with full latency stations and dual latency stations Lo, Edward Chi Lup
A method of performance improvement of token ring networks is presented, based on the use of stations with two latency states. Station latency is defined as the time delay introduced in passing data through a station. Most token ring protocol standards (e.g. IEEE 802.5 or ANSI X3T9.5) require incoming data to be decoded and encoded in the station before transmission onto the ring. These encoding and decoding operations add significantly to the station latency. The bypassing of the encoding and decoding steps is proposed, which improves the mean message waiting time. A detailed evaluation and comparison of the networks is based on both analytical and simulation results. The performance of identical stations and symmetric traffic is obtained analytically. A discrete event simulation model for a token ring network is written in GPSS for general traffic. Results show a significant reduction in mean waiting time for the dual latency ring, with performance approaching or exceeding that of gated and exhaustive service, for certain ranges of network utilization.
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