Fiber Distributed Data Interface Network Research Articles

Analytical method for analyzing message transmission processes in FDDI networks for digital substations

Objectives. To develop analytical approaches for the evaluation of probability-time characteristics and fiber distributed data interface (FDDI) network performance with the marker access method, thus enabling communication processes for digital electrical substations to be automated.Methods. The authors used theory reliability methods, random process theory, mass maintenance theory, the Laplace–Stieltjes transformation for inferring functional equations and the probability-time characteristics calculation for the information transfer processes with the occurring failures.Results. We conducted a numerical study of packet transfer processes between central processing stations in the FDDI network. We considered the processes of discrete information exchange between electronic devices in the system of electrical digital substations. These included the main technological operations and electrical digital substations operator performed when preparing reports. We described the different modes of operation, both for the individual electrical digital substation and for the system. The authors calculated node loading dependencies, FDDI network performance and temporal characteristics of the packet transfer processes on the incoming message flow intensity and the transmission medium reliability. We conducted a functional analysis of the FDDI networks on two fiber-optic rings which form the main and redundant path of data transfer between the network nodes, significantly increasing network resiliency. The objective of the study was to analyze the information transfer processes in FDDI networks with an accent on ensuring the transmission medium reliability.Conclusions. We were able to establish the existence of the critical operating network region, which leads to a sharp increase in node load and temporal characteristics, while performance reaches its maximum value and then sharply decreases. We propose the exchange of discrete messages to reflect the electronic devices state and information messages of operator between various remotely spaced electrical digital substation with the FDDI fiber-optic network.

Fault-tolerant, real-time communication in FDDI-based networks

The first high-speed network to meet the Safenet standard's bandwidth requirements, the Fiber Distributed Data Interface (FDDI) needs help to meet Safenet's fault tolerance requirement. Researchers have proposed a number of FDDI-based network architecture designs for improving fault tolerance. An architecture called FBRN (FDDI-Based Reconfigurable Network) provides enhanced fault tolerance by using (a) multiple FDDI networks to connect hosts, and (b) efficient fault detection and network configuration algorithms. To provide fault-tolerant real-time communication with the FBRN architecture, users must manage network resources properly. We sought to accomplish this by using a fault-tolerant, real-time management mechanism with online and offline components. We focused on achieving high performance by designing efficient and effective online and offline management algorithms to work around multiple faults.

Analysis of an FDDI network supporting stations with single-packet buffers

We present exact analysis of a nonsymmetric multiple-priority token ring network with single packet buffers under a timedtoken protocol, similar to that employed for medium access control of the Fiber Distributed Data Interface (FDDI) network. The single-packet buffer model is employed for describing the queueing operation characterizing typical user terminals. An iterative procedure is used to compute the limiting state distribution of the embedded Markov chains representing the system state process. We obtain the distributions of the token rotation time, the normalized throughput, and the mean packet waiting time. By using a counting process representing the numbers of transmitted and deferred packets in a token rotation cycle, we present a simplified analysis of a symmetric network containing a large number of stations. We illustrate the application of the analytic approach through numerical examples representing FDDI network systems operating under various traffic loading conditions.

Large picture archiving and communication systems of the world--Part 2.

A survey of 82 institutions worldwide was done in 1995 to identify large picture archiving and communication systems (PACS) in clinical operation. A continuing strong trend toward the creation and operation of large PACS was identified. In the 15 months since the first such survey the number of clinical large PACS went from 13 to 23, almost a doubling in that short interval. New systems were added in Asia, Europe, and North America. A strong move to primary interpretation from soft copy was identified, and filmless radiology has become a reality. Workstations for interpretation reside mainly within radiology, but one-third of reporting PACS have more than 20 workstations outside of radiology. Fiber distributed data interface networks were the most numerous, but a variety of networks was reported to be in use. Replies on various display times showed surprisingly good, albeit diverse, speeds. The planned archive length of many systems was 60 months, with usually more than 1 year of data on-line. The main large archive and off-line storage media for these systems were optical disks and magneto-optical disks. Compression was not used before interpretation in most cases, but many systems used 2.5:1 compression for on-line, interpreted cases and 10:1 compression for longer-term archiving. A move to digital imaging and communication in medicine interface usage was identified.

Performance analysis of small FDDI networks

Fiber Distributed Data Interface (FDDI) networks offer a standardized, high-speed interconnection between components in a distributed computer system. Extensive research has been conducted on the performance of FDDI networks consisting of hundreds of stations distributed over an area of several hundred square meters. This paper extends the prior work to the case of small networks; for example 10 stations distributed around a single room laboratory. The characteristics for these smaller networks differ in some instances from the behavior of larger networks - these differences can be significant in applications where high performance is demanded from a small FDDI based network.

Throughput analysis of a transport protocol in an FDDI network

AbstractThis paper analyzes the throughput of a transport protocol, such as the ISO transport protocol class 4 (TP4) and the transmission control protocol (TCP), in a fiber distributed data interface (FDDI) network. It also studies the influence of the target token rotation time (TTRT), ring latency, window size, and frame length on the throughput performance in cases of both symmetric traffic and asymmetric traffic. Furthermore, the throughput is compared with that of FDDI without transport protocol in order to quantify the overhead of the transport protocol. Numerical results indicate that the influence of window size and frame length on the throughput is larger than that of ITRT.

Deferring real-time traffic for improved non-real-time communication in FDDI networks

The fiber distributed data interface (FDDI) is suitable for real-time communication because of the high speed and the performance guarantees it provides. However, these guarantees are achieved at the expense of non-real-time traffic because the real-time messages are given higher priority over non-real-time messages,resulting in excessive delays for non-real-time messages. In this paper, we propose a scheme for reducing the response time of non-real-time messages while still providing the same guarantees to real-time messages. In particular, the proposed approach gives higher priority to real-time messages only when it is absolutely necessary in order for them to meet their deadlines. Non-real-time messages are thus transmitted ahead of real-time messages whenever possible. We present an algorithm for determining when and by how much the transmission of a real-time message can be deferred without jeopardizing its deadline. The proposed approach is evaluated through simulation. The simulation results show that a substantial reduction in the mean response time of non-real-time messages is achieved when using the proposed approach.

Analysis of an M/G/1/N queue with vacations and its iterative application to FDDI timed-token rings

We present the analysis of an M/G/1/N queueing system with vacations under a dynamic time-limited service policy. This method is used to develop a procedure for performance analysis of a fiber distributed data interface (FDDI) network serving buffer-limited stations under asynchronous service. An efficient iteration procedure is employed to evaluate the limiting state distribution of the embedded Markov chain representing the system state process. Using supplementary variables and sample biasing techniques, we derive the queue size distribution at an arbitrary instant of time as well as the packet blocking probability and the mean packet delay. By exploiting the subtle structure of conditional supplementary variables and the recursive property of the conditional residual delay, the Laplace-Stieltjes transform of the packet delay distribution and a time-domain approximation of the packet delay distribution are obtained. For the analysis of a heterogeneous multi-station FDDI network, an iterative procedure which uses repeatedly the M/G/1/N vacation model described above is presented. This procedure provides for a numerically efficient analysis method by employing constructions of the approximate vacation time distributions. We illustrate the application of our analytical techniques to both symmetric and nonsymmetric FDDI network systems.

Fiber distributed data interface: throughput evaluation with multiple classes of traffic

The fiber distributed data interface (FDDI) standard supports synchronous and asynchronous data transmissions. It allows each station to have multiple classes of asynchronous data, and meets the requirements of different classes by means of a timer-based priority scheme. The performance of a FDDI network carrying multiple classes of traffic is considered. An analytical model is presented to evaluate the throughput of synchronous traffic and asynchronous traffic. The model can be used to evaluate the throughput of individual priority classes and the mean token-cycle time of the network, when the network offered load varies from very low values to high values. The governing equations for the throughput characteristics and mean token-cycle time are strictly functions of network parameters. Simulations are used to verify the analytical model. Simulation results are also used to examine the variation of the mean access delay characteristics of various classes and the token-cycle time distribution of the priority scheme. Limitations of the model are outlined. >

Design and implementation of a desktop computer supported cooperative work system

Describes the implementation of a desktop CSCW (computer supported cooperative work) system using commercially available consumer electronic devices and facilities. The system is developed on workstations under UNIX and OPEN LOOK environments connected by FDDI (fiber distributed data interface) networks. It provides multiparty conference with shared white board. Shared text editor, calendar, and voting capability. Each conference with these features can support a groupware environment. The design and consideration of the framework of the system is presented. During the implementation, some performance issues such as error control, medium synchronization and throughput improvement are also discussed. >

VirtualTalker: an online multimedia system on token passing networks

VirtualTalker, a multimedia system based on the PC and/or workstation environment, is described. This system has been developed on the token ring and FDDI (fiber distributed data interface) network running the TCP/IP (transmission-control-protocol/Internet protocol) suite. This system allows people to interactively communicate with each other at different locations through video phone and shared white board services. VirtualTalker basically consists of two applications. The VideoPhone application transmits video and voice simultaneously while the ScratchTalker application provides the telephone service with a shared white board by using a tablet. Since the system transmits real-time traffic such as video and voice over the network, many design and technical issues such as the network protocol, encoding technique, delay jitter, packet size, synchronization of video and voice, and priority assignment are considered. >

Continuous media communication with dynamic QOS control using ARTS with an FDDI network

Continuous media communication requires timely delivery of data such as digital video and audio packets. Quality of Service (QOS) parameters specify the temporal and spatial characteristic of such continuous media data. To insure timely delivery of continuous media data, the system needs to minimize the communication delay by securing required processor and network resources. We have extended the Capacity-Based Session Reservation Protocol(CBSRP), which was proposed to realizing predictable real-time communications, to support dynamic control of QOS. We have implemented a QOS control scheme by which the network dynamically adjusts the allocations of network bandwidth on a Fiber Distributed Data Interface(FDDI) network. In this paper, we describe the definition of our QOS model, the extension of CBSRP to support dynamic control of QOS, and the implementation and evaluation of extended CBSRP in our distributed systems testbed, Advanced Real-Time System(ARTS).

Distributed Bandwidth Management in FDDI Networks with Multiple Isochronous Services

The Fiber Distributed Data Interface (FDDI) is a proposed American National Standard for a 100 Mbps token ring using an optical fiber medium. The timed token protocol used in FDDI allows the integration of digital voice, video, interactive data communications and large file transfers over the same network. The performance of the protocol has been studied in the past for asynchronous class of service with a single isochronous service.In this paper, we focus on the performance of the protocol when multiple class of isochronous services are to be provided along with the asynchronous class of service. It is found that the performance of the protocol is affected by the different delay requirements of different isochronous services. The performance of the protocol is studied through simulation with two classes of isochronous services viz video and voice. We also propose two distributed algorithms to improve the performance of the protocol under multiple isochronous services.

High performance distributed computing in FDDI networks

Distributed computing requirements are discussed, and distributed computing in FDDI (fiber distributed data interface) networks is considered. Three applications with different requirements are examined to show how the basic FDDI topology (a dual ring of trees) and mix of station types can he matched to the throughput and reliability requirements of particular applications. These applications are: an engineering graphics application, characterized by high throughput requirements, small workgroups, low-to-medium network reliability requirements, and high-end workstations and graphics servers: an office application, characterized by reasonable response time requirements, connectivity requirements (to corporate networks, both local and wide area), high network reliability requirements, and many PCs and low-end workstations and servers (e.g., print and file); and a military application, characterized by high throughput requirements, low response time requirements, very high network reliability requirements, and a mix of high-end and low-end workstations and servers. FDDI and distributed computing performance considerations are addressed. Tools to support FDDI applications are discussed. >

Performance analysis of FDDI token ring networks: effect of parameters and guidelines for setting TTRT

The timed token access method on which the FDDI (fiber distributed data interface) network is based is described. The two kinds of performance parameters, fixed and user-settable, that are used to study performance are discussed. Performance metrics are defined, and the performance is analyzed for asynchronous traffic, using simulation and analytical modeling. Guidelines for setting the target token rotation time (TTRT), which is the key network parameter that can be used to optimize the performance of an FDDI ring network, are presented. The effects on performance of the total number of stations, number of active stations, frame size, and total fiber length are examined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An FDDI network for tactical applications

A fiber-optic tactical local area network (FOTLAN), based on the fiber distributed data interface (FDDI), that supports data packet traffic simultaneously with synchronous traffic is described. The current US Army LAN implementation is examined, and its limitations are highlighted. An overview of a migration path from the current LAN to the ATCCS (Army tactical command and control system) objective system using FOTLAN is presented to demonstrate how such a network can evolve. >