2,784 research outputs found

    Throughput analysis of the IEEE 802.4 token bus standard under heavy load

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    It has become clear in the last few years that there is a trend towards integrated digital services. Parallel to the development of public Integrated Services Digital Network (ISDN) is service integration in the local area (e.g., a campus, a building, an aircraft). The types of services to be integrated depend very much on the specific local environment. However, applications tend to generate data traffic belonging to one of two classes. According to IEEE 802.4 terminology, the first major class of traffic is termed synchronous, such as packetized voice and data generated from other applications with real-time constraints, and the second class is called asynchronous which includes most computer data traffic such as file transfer or facsimile. The IEEE 802.4 token bus protocol which was designed to support both synchronous and asynchronous traffic is examined. The protocol is basically a timer-controlled token bus access scheme. By a suitable choice of the design parameters, it can be shown that access delay is bounded for synchronous traffic. As well, the bandwidth allocated to asynchronous traffic can be controlled. A throughput analysis of the protocol under heavy load with constant channel occupation of synchronous traffic and constant token-passing times is presented

    A study of topologies and protocols for fiber optic local area network

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    The emergence of new applications requiring high data traffic necessitates the development of high speed local area networks. Optical fiber is selected as the transmission medium due to its inherent advantages over other possible media and the dual optical bus architecture is shown to be the most suitable topology. Asynchronous access protocols, including token, random, hybrid random/token, and virtual token schemes, are developed and analyzed. Exact expressions for insertion delay and utilization at light and heavy load are derived, and intermediate load behavior is investigated by simulation. A new tokenless adaptive scheme whose control depends only on the detection of activity on the channel is shown to outperform round-robin schemes under uneven loads and multipacket traffic and to perform optimally at light load. An approximate solution to the queueing delay for an oscillating polling scheme under chaining is obtained and results are compared with simulation. Solutions to the problem of building systems with a large number of stations are presented, including maximization of the number of optical couplers, and the use of passive star/bus topologies, bridges and gateways

    Performance analysis of the Fiber distributed data interface (FDDI) network using petri nets and SPNP software package

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    The main purpose of this thesis is to model a Fiber Distributed Data Interface (FDDI) Network using Petri Nets, and to analyze its performance with the help of the SPNP software package. The verification of a communication protocol, by modeling it as a discrete-event system using Petri Nets is a new approach. The correlation between the throughput rate, voice and data throughput, and the parameters of the system, such as the network load and the network speed are investigated. An overview of the Fiber Distributed Data Interface is provided, along with its network protocol and the limitations of its operating parameters. A proposed Petri Net approach is then introduced. Finally, the effect of the network latency and load on the network\u27s overall performance is derived. A method for minimum delay is also proposed, and demonstrated with examples and computation results

    Mapping Technological Trajectories as Patent Citation Networks. An application to Data Communication Standards

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    Technical systems, Technological trajectories, Patents, Network analysis, Data communications

    Analysis of a queuing model for slotted ring networks

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    We study a multi-server multi-queue system which is intended to model a local area network with slotted ring protocol. Two special cases of the model are analysed and the results are used to motivate an approach to approximate mean queue lengths in the general model

    Performance of buffer insertion LANs

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    This thesis presents an evaluation of the performance of some ring local area network protocols, specifically the buffer insertion ring and the token ring. Both dual and single versions of each are considered, and performance statistics are obtained by measurements on real networks, by mathematical analysis, and by computer simulation. New packet routing protocols for dual contrarotating buffer insertion and token ring networks are described and their performance is examined. It is found that, due to the bandwith reuse properties of the routing methods, maximum throughputs of 800% and 200% are achievable, for the dual buffer insertion ring and the dual token ring respectively
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