A Performance Analysis of Buffered DQDB Network with Request Arrival Process Depending on Its Request Counter Value and Its Location on the Buses

Shu LI
Yasumitsu MIYAZAKI

IEICE TRANSACTIONS on Communications   Vol.E81-B       pp.493-502
Publication Date: 1998/03/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Category: Communication Networks and Services
MAN,  DQDB,  high speed bus networks,  multiaccess,  Markov chain,  throughput,  packet delay,  

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The location of stations on the buses can not be ignored in the analysis of the DQDB protocol, especially when traffic load is heavy. In this paper, we propose a new method to model the DQDB (Distributed Queue Dual Bus) protocol by assuming that the request arrival process depends on both the value of the request counter and the location of a station on the buses. By taking these dependences, we can catch the real behavior of the DQDB stations, which is locationally dependent and unfair under heavy load traffic. Based on this model, we analyze the DQDB system with finite buffer by considering the request counter states and buffer states separately and obtain the throughput, mean packet delay and packet reject probability of individual stations. The throughput in individual stations matches that of simulation very well within the range of traffic up to the channel capacity. Also the delay and packet reject rate performance is good up to moderate traffic load. These numerical results reveal the properties of the location dependence and the unfairness of DQDB system under heavy load condition. The analytic results under heavy load traffic for a general DQDB system has not been reported till now. Therefore we conclude that our model and analysis are valid and effective.