An Approximate Analysis of a Prioritized Token Passing Method in Ring-Shaped Local Area Networks

Takeshi NISHIDA  Masayuki MURATA  Hideo MIYAHARA  Kensuke TAKASHIMA  

IEICE TRANSACTIONS (1976-1990)   Vol.E69   No.1   pp.29-39
Publication Date: 1986/01/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Communication Networks

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We present a new access protocol with priority functions in a ring-shaped local area network utilizing the token passing method. This protocol provides an asynchronous TDMA scheme to the terminals with the low class traffic, and the terminals with the high class traffic can transmit their messages between the consecutive transmissions of low class traffic. The protocol is shown to be effective for the environment where multifarious traffic is accommodated in the network. It gives the higher priority in transmission to the traffic which requires the real time transmission, while the lower priority is given to the one which may not require so strict real time transmission. We provide an approximate analytical method for obtaining the average message delay in our protocol. The performance of our protocol is compared with that of existing access protocol for two example network models, one is the network with balanced load and the other is not. As a result, it is observed in both the example networks that the characteristics of transmission delay for the messages with higher priority is much improved compared with other existing method without introducing much service degradation for lower priority traffic.