基于时控令牌协议的分布式系统临界区访问算法及其排队模型

THE ACCESS METHOD AND QUEUEING MODEL BASED ON TIMED-TOKEN PROTOCOL FOR CRITICAL REGION IN DISTRIBUTED SYSTEM

本文结合在分布式光纤数据接口 ＦＤＤＩ中应用的时控令牌协议，对现有分布式系统临界区互斥访问的令牌环算法进行了改造，使得令牌循环一周的时间得以有效控制，从而为丢失令牌的判断提供了理论依据。本文进一步对系统模型进行了分析，建立了相应的排队模型，并对一种简化模型Ｌ／Ｄ／１／１／ＦＣＦＳ（相关）进行了解析和模拟实验。模拟实验结果显示时控令牌协议下的系统稳定状态是两个稳定状态交替出现形成的。

On the base of the timed-token Protocol, Which is applied in the Fiber Distribrted Data Interface(FDDI), this paper improves the token ring algorithm, a known mutual exclusion methods for a Process to access to critical region in distributed system, to provide principle base for the distinguishing of loss of token from a long time rotation by confining the rotation in a short time. Furthermore, Two queueing models are set up behind the system model's analysis. The simpler one is analyzed in this paper and emulation experiments is given out, in which a significant result shows that the system under a timed-token protocol is converged to two alternative states.