This paper considers the basic access mechanism in asynchronous transfer mode (ATM)-oriented rings which, like Orwell, ATM ring, and ALine, apply destination release of used slots. The released slots may be reused by the destination station, or in some protocols, they must be given to the next station. Such a mechanism can be modeled by a multiple-server multiqueue system, where switchover times between consecutive polling instants of the queues are nonzero. The server polls the queues according to a certain polling discipline, which is dependent on the service time. This paper presents approximate mean minipacket waiting times in such systems. The approximation is based on a polling queueing model with Markovian server routing. Poisson arrivals and a symmetric workload model for minipackets having a full and partial traffic matrix are assumed. The performance characteristics are compared between the alternative options.

The structuring, services, and major protocol functions that are required in the upper layers of the OSI reference model in order to support end-to-end multimedia communication, assuming a simple transport service, are examined. It is assumed that variable-bit-rate (VBR) coding techniques will be used in future multimedia systems. Mutual stream synchronization, integral management, and multiparty connections, which appear to be crucial issues in multimedia communication, are addressed. Important implementation and performance issues are discussed.>

Performance of the Cambridge Fast Ring (CFR), a high-speed slotted ring with normal slots, is studied. It is shown that the CFR can be represented by a multiqueue multiple cyclic server model with a 1-limited service discipline and with a restriction that only one server at a time can be serving a queue. Exact necessary and sufficient stability conditions are stated. An approximate analytic M/G/1 vacation model in which analysis concentrates on one station while the others are represented by a vacation period is developed to estimate the expected message waiting times. It is shown that the model is accurate and usable over a wide range of parameters. A performance evaluation of the CFR based on this model is presented. The performance is compared to that of a variant which does not restrict the number of slots a station may simultaneously use.>

The slotted ring protocol which is evaluated in this paper is suitable for use at very large transmission rates. In terms of modelling it is a multiple cyclic server system. A few approximative analytical models of this protocol are presented and evaluated vs the simulation in this paper. The cyclic server model shows to be the most accurate and usable over a wide range of parameters. A performance analysis based on this model is presented.

The performance of a number of slotted-ring protocols supporting integration of synchronous and asynchronous traffic in high-speed local area networks (HSLANs) is evaluated. They are the Cambridge fast ring, a variant of the Cambridge fast ring, and Orwell. The performance of their basic access mechanisms is compared and contrasted with that of the multiple-token ring. The effect of a uniframe scheme for supporting synchronous traffic is examined. A delay analysis of the integrated-services slotted-ring protocols is presented.>