Fiber Distributed Data Interface Research Articles

Performance Investigation of Fiber Distributed Data Interface in Networking

Abstract: The extent of the ring, the number of stations on the ring, the number of stations waiting to communicate, and the frame size are all setup and workload characteristics that affect the performance of an FDDI LAN. In addition, the target token rotation time is a significant parameter that network management may regulate to optimise performance (TTRT). The influence of the TTRT on various performance indicators for different ring topologies was investigated using analytical modelling and simulation approaches. The performance of the FDDI network is the topic of this research. The functionality of the FDDI network was then assessed in terms of efficiency, reaction time, and network cost using various values of ring latency, fixed target token rotation time (TTRT), and number of stations. The entire project is done in MATLAB. Keywords: FDDI LAN, TTRT, Interface, Networking, MATLAB

An Optimized Salahaddin University New Campus IP-Network Design using OPNET

Salahaddin University is the oldest and the biggest university in Kurdistan region. It involves 14 colleges and 3 academic centers. The new university campus that will be established on an area of 10km2 provides a challenge of designing, efficient and robust networking infrastructure due to increased demand on data and data processing applications like FTP (File Transfer Protocol) which is a vital protocol in an academic environment. At access layer (college level) Wireless Local Area Network (WLAN) is employed to provide Wi-Fi to the end user for ultimate mobility. At backbone level four scenarios have been proposed and tested for a proposed university campus. These scenarios used to connect each college Wi-Fi router to Cisco core switch (6509). The first scenario uses optical fiber cable 1000Base-LX (Gigabit- Ethernet), while in the second scenario the Virtual Local Area Network (VLAN) based core switch is used to connect (Gigabit- Ethernet) cables. The third scenario uses FDDI (Fiber Distributed Data Interface) technology. In the fourth scenario, a combination of the VLAN based core switch and FDDI is presented. In the four scenarios, the core switch is connected to the main router Cisco (7507) which connects the campus network to the cloud. The network performance and behavior have been studied by calculating network load throughput and delay. The system has been implemented using OPNET (Optimized Network Engineering Tool) simulator modular 14.5. The simulation results show that the fourth scenario gives minimum delay while maximum data transfer (throughput) is achieved by the fourth scenario.

Book Review: Writing for Digital Media

Brian Carroll Writing for Digital Media. New York, NY: Routledge, 20 1 0. 313 pp.Finding a good text for an journalism course can be a challenge. While discussions of Web technology and software are, of course, key parts of producing digital content, they can easily squeeze out room for consideration of the main point: writing. Some texts, therefore, are left discussing itself in two chapters, one called something such as online writing and the other linking.Such is not the case in Carroll's book. This well-researched and thoughtfully organized work honors the craft of through its own production.The book is presented in three sections. Part I begins with an excellent examination of good and the foundations of good journalistic form. It then introduces students to the differences between reading content in print versus digital form and why digital necessitates considerations of scanning, readability, and search for the writer. The second chapter ends with a brief introduction to HTML, XHTML, and CSS.Part II, chapters 3 through 6, segues into a deeper presentation on planning and mapping news sites; yet style remains the key. The third chapter concludes by examining the visual style of three well-known sites, C/Net, Razorfish, and Google, and recommends the overlooked practice of storyboarding to plan clean page design. Consideration of the visual, again, is tied into the concept of reader usability, which is as it should be for a text.Chapter 4 centers around the importance of heads, subheads, and links; following a brief discussion of text types, the chapter ends with the practice of chunking and illustrates how it was used in two case studies.Chapter 5 brings up one criticism: its focus on designing news sites and pages might easily have been incorporated into chapter 3. Instead, the text seems to bog down somewhat with considerations of balance, contrast, and unity. For example, the text's explanation of style guides might confuse students because it comes so close at times to mixing editorial style guidelines (such as the AP's) with coding guides or software terminology. When presenting file names, use only lowercase letters. Examples: florence.wmv . (p. 113).Or consider this: As examples, here are two terms and their style explained from Wired's usage book: FDDI: Pronounced 'fiddy' and standing in for 'fiber distributed data interface,' this fiberbased network architecture offers a faster and more dependable alternative to ether or Token Ring. (It transmits at 1 OO Mbits per second over LANs and MANs.) Of course, with gigabit Ethernet on the horizon, the future of FDDI looks bleak' (p. 113).So would an undergraduate's expression, I can imagine.Chapter 6 rights its way again with important advice on editing. Not only is editing given its due, which is rare in other texts, but Carroll presents step-by-step methods students can use in their editing attempts.Part III, chapters 7 through 1 1 , covers the many different contexts in which has become a valuable skill - through blogging, citizen journalism, and corporate communication - and concludes with a comprehensive and well-written summary of key legal concepts that impact writers. An Afterword reflects upon the core values in journalism and helps students realize they are the same as those in print journalism: accuracy, transparency, fairness, and independence. …

HIGH THROUGHPUT OF ASYNCHRONOUS TRAFFIC AND MAXIMUM CAPACITY OF SYNCHRONOUS SOURCES WITH THE NEW FDDI'S MAC PROTOCOL

It is well known that Fiber Distributed Data Interface (FDDI) offers an excellent cost-benefit and guarantees a reliable and powerful network. It is also fact that the FDDI is suitable for synchronous traffic because of the high speed and the performance guarantees it provides. However, these guarantees are achieved at the expense of asynchronous traffic because the synchronous messages are given highest priority over asynchronous messages, resulting in excessive delays and low throughput for asynchronous message. This paper, presents a modification of the FDDI's MAC(Media Access Control) protocol to control the maximum token rotation time not to exceed the TTRT (Target Token Rotation Time) in the worst case, the realization of this condition leads to set the TTRT to the message generation period (Tg) instead of one half of it (Tg/2). The new protocol of FDDI’s MAC increasing both the throughput of asynchronous traffic and the capacity of synchronous sources. The proposed MAC is evaluated by means of computer simulation. The simulation results confirm that the new proposed MAC provides FDDI more efficient for supporting multimedia applications.

Improving the compression and encryption of images using FPGA-based cryptosystems

Compression and encryption technologies are important to the efficient solving of network bandwidth and security issues. A novel scheme, called the Image Compression Encryption Scheme (ICES), is presented. It combines the Haar Discrete Wavelet Transform (DWT), Significance-Linked Connected Component Analysis (SLCCA), and the Advance Encryption Standard (AES). Because of above reason the ICES efficiently reduce the overall processing time. This study develops a novel hardware system to compress and encrypt an image in real-time using an image compression encryption scheme. The proposed system exploits parallel processing to increase the throughout of the cryptosystem for Internet multimedia applications to implement the ICES. Using hardware acceleration for encryption and decryption, the FPGA implementation of DWT, SLCCA and the AES algorithm can be used. Using a pipeline structure, a very high data throughput of 330 Mbit/s at a clock frequency of 40 MHz was obtained. Therefore, the ICES is secure, fast and suited to high speed network protocols such as ATM (Asynchronous Transfer Mode), FDDI (Fiber Distributed Data Interface) or Internet multimedia applications.

DMD Measurements and Equalization Simulations for 62.5- and 50-<tex>$muhboxm$</tex>Legacy Multimode Fibers at 1300 nm

We present the results from the differential modal delay (DMD) measurements at 1310 nm performed over a large sample of 62.5- and 50-μm fiber distributed data interface grade multimode fibers (MMF). We have found that the typical DMD values are in the range 0.5-1.5 ps/m, but a significant portion of the measured fibers have DMD values exceeding the commonly used value of 2 ps/m. Since the expected yield at moderate (150-300 m) distances of 10 Gb/s links employing legacy fibers is very poor, we have simulated equalization techniques in the receiver for the measured fiber impulse responses. We show here that both the yield and the achievable distance are improved when equalization is used.

The timely token protocol

The token protocols in fiber distributed data interface (FDDI) and modified FDDI (FDDI-M) support synchronous and asynchronous traffic. However, FDDI suffers from a token-lateness problem, and FDDI-M may starve asynchronous traffic. To remove these two weaknesses, we propose the timely token protocol. The main feature of this protocol is the addition of information to the token so that each station may determine the reason of an early token arrival. Using this information, each station limits its asynchronous transmission to ensure that the token is not late at subsequent stations. In addition, we present a synchronous allocation scheme for this protocol. Finally, a comparison is made against FDDI and FDDI-M.

Determining the Asynchronous Threshold Values of the Timed Token Medium Access Protocol

Due to its timed-token medium access control protocol, fibre distributed data interface is suitable for transmitting real-time and non-real-time data. Several protocol parameters should be properly selected to satisfy the time constraints of the synchronous messages and to provide the maximum usage of the asynchronous transmission bandwidth. In this study the effect of asynchronous threshold values on the behaviour of the ring is considered, and two methods are developed to calculate suitable threshold values for different purposes. In the first method the proper asynchronous threshold values are calculated to share out the asynchronous bandwidth between nodes in given proportions. In the second method, asynchronous data transmissions of nodes are limited by using appropriate asynchronous threshold values. In this way the actual target token rotation time can be reduced to facilitate achieving the real-time requirements of synchronous messages.

The distributed control and data system in HT-7 tokamak

A control and data processing system for HT-7, the first super-conducting tokamak in China, is developed in order to both control the experimental system and process the huge amount of experimental data (600 MB/shot). A fully distributed structure is adopted. The distributed control system (DCS) includes several subsystems, such as those for the main control, synchronization, safety, interlock, data acquisition and data analysis, physical data management, remote control facility via networks, etc., The basic element of the DCS is the personal computer (PC) with a Fiber Distributed Data Interface based on a fast network. The system uses multiple data-transfer paths in parallel and categorizes the entire computer functions into the servers. The subsystems for main control, communication, and data management are described in detail.

Testing the Schedulability of Synchronous Traffic for the Timed Token Medium Access Control Protocol

One of the key issues related to guaranteeing synchronous message deadlines in a timed token network (such as fiber distributed data interface) where the timed token medium access control protocol is used is the schedulability test of synchronous traffic (i.e., testing whether or not all synchronous messages can be transmitted before their deadlines, under a given setting of network parameters). Much work has been done on how to assign network parameters appropriately in order to guarantee timely transmission of synchronous traffic. As a result quite a few synchronous bandwidth allocation schemes and some good guidelines on selection of the target token rotation time have been proposed. In contrast, limited research has been conducted on how to effectively test whether or not given network parameters can guarantee timely transmission of all synchronous messages (of a considered synchronous message set) before their deadlines. The previous testing methods for synchronous message schedulability only provide a sufficient (but not necessary) test and therefore fail to always keep effective for any synchronous message set considered. In this paper, we propose two testing methods for determining the schedulability of a synchronous message set with message deadlines no longer than periods. The proposed tests perform better than any previous test in the sense that they are both sufficient and necessary. Some numerical examples are given to compare different testing methods, all of which have demonstrated the superiority of the proposed tests to other existing testing methods.

Effectiveness of the FDDI-M protocol in supporting synchronous traffic

Timed token networks such as fiber distributed data interface (FDDI) networks have been widely deployed to support synchronous traffic. However the medium access control (MAC) protocol of FDDI allows transmission of synchronous messages up to at most one-half of the total bandwidth of the network. Shin and Zheng have proposed a modification to the FDDI MAC protocol, called FDDI-M, which can double a ring's ability in supporting synchronous traffic (K.G. Shin, G. Zheng, IEEE Transactions on Parallel and Distributed Systems 6 (1995) 1125–1131). It is widely known that the ability of timed token protocols such as FDDI to guarantee synchronous message deadlines is very dependent on the synchronous bandwidth allocation (SBA) schemes used, but the original paper does not address this issue. In this paper, we will compare the ability of FDDI-M to support synchronous traffic under different SBA schemes with that of FDDI. We use a new taxonomy of SBA schemes based on the strategy used to partition the synchronous bandwidth, and present an analytical study of the timing properties of the FDDI-M protocol using the worst case achievable utilization (WCAU) as the performance metric. The results show that while FDDI-M improves the WCAU values under one class of SBA schemes, its performance under the other category of SBA schemes is mixed. We also perform extensive simulation to study performance of FDDI-M for MPEG video traffic, and conclude FDDI-M does outperform FDDI significantly at heavy load. The effect of SBA schemes under overload conditions is also shown to be relatively minor, with the local SBA schemes actually performing better than the global schemes.

Game-Theoretic Approach to the Optimization of FDDI Computer Networks1

The problem of maximizing the performance in a fiber distributed data interface (FDDI) computer network is formulated as a cooperative n-player game. Solutions of this game can be obtained by solving special optimization problems. Using the models and formulas developed by Tangemann (Ref. 1) and Klehmet (Ref. 2) for the mean waiting times, the resulting optimization problems are presented and numerical results are given.

PACS: the second time around

Conquest Hospital was a Picture Archiving and Communication Systems development site, designed to inform the specification of low cost systems and to provide information on benefits and drawbacks. The American College of Radiologists/National Electrical Manufacturers Association 2.0 protocol was used for image management. The Regional Health Authority sponsored the system, initially installed in mid 1992. It used a high-speed dedicated optical fibre distributed data interface network and for teleradiology an Integrated Services Digital Network solution. Image and other data were captured and archived satisfactorily. Image reporting folders were manually constructed and sent to reporting viewstations. Radiologists were able to directly request ‘ad hoc’ images from archive. The reporting function of the associated but unlinked radiology information system was satisfactory. Identification was made of data transfer, ergonomic, single point of failure and many other issues. These informed re-specification and the commercial approach for a Digital Images Communication in Medicine/Hyper Text Mark-up Language Picture Archiving and Communication System, the first stages of which have been whole hospital re-networking, Intranet introduction, installation of new Computed Radiography/Fluorography and Computed Tomography/Magnetic Resonance Imaging segments and a new Radiology Information System. The Picture Archiving and Communication System is now seen as part of a full Electronic Patient Record system. Networking and provision of high quality Personal Computer hardware for data review are seen as a corporate responsibility and a hospital overhead, no longer borne by individual projects. Our present work is synergistic with the procurement of a new Clinical Information System and the further development of the hospital Intranet.

Wireless optical transmission of fast ethernet, FDDI, ATM, and ESCON protocol data using the TerraLink laser communication system

The TerraLink laser communication (lasercom) system was developed as a cost-effective, high-bandwidth, wireless alternative to fiber optic transmission. The advantages of lasercom over fiber optic cabling are primarily economic. However, free-space lasercom is subject to atmospheric effects, such as attenuation and scintillation, which can reduce link availability and may introduce burst errors not seen in fiber transmission. The TerraLink transceivers use large receive apertures and multiple transmit beams to reduce the effects of scintillation. By designing the lasercom link with sufficient margin for atmospheric attenuation and scintillation, a bit error rate (BER) of 1029 or better can be achieved. Since we designed the TerraLink transceivers to be eye-safe at the transmit aperture, each system is range-limited. Link power budgets for the TerraLink systems are presented, and link margin data are shown that quantitatively describe how the effective laser link range varies in different weather conditions. Since the TerraLink transceivers act as simple repeaters, they are protocol-independent. Examples of TerraLink installations transmitting wireless fast ethernet (125 Mbits/s), fiber distributed data interface (FDDI) (125 Mbits/s), asynchronous transfer mode (ATM) (155 and 622 Mbits/s), and Enterprise Systems Connection (ESCON) (200 Mbits/s) protocol data are presented.

Interconnecting LANs and a FDDI Backbone Using Transparent Bridges: A Model and Solution Algorithms

In this article, we construct a mathematical model to design the topology of a network interconnecting a number of local area networks (LANs) and a fiber-distributed data interface (FDDI) backbone using IEEE 802.1 transparent bridges. The model allows parallel bridge links between subnets and yields a two-node-connected topology for survivability. The model determines the routing tree on a given topology according to the IEEE Standard protocol, which uses as input only user-supplied parameters such as bridge IDs, port IDs, and path costs. The model ensures that none of the network components (LANs, FDDI, and bridge links) are congested even in the failure of a LAN or a bridge link. We develop a path cost adjustment algorithm and a tabu search algorithm to find a low-cost feasible topology. Through computational experiments, we identify the characteristics of feasible topologies found under varying traffic conditions. Under light traffic conditions (i.e., when LANs' total slack capacity is large relative to the total intersubnet traffic demand), the topology is close to a ring which costs much less than the conventional star topology. Under heavy traffic, the topology tends to be a ring augmented by parallel bridge links between LANs and the FDDI. Finally, we discuss how effective various heuristic ideas—such as uncapacitated, two-connected topology design heuristics, the short-term tabu list and the long-term tabu list—are with respect to improving the solution quality. We also present a Lagrangian relaxation-based lower bounding procedure and report the gap between the best feasible value and the lower bound. The parsimonious property of uncapacitated, two-connected topology design problems is employed in this dual partitioning procedure.

High speed fiber optics backbones

In late 1995, the data communications networks at the Fletcher Challenge Canada's Crofton pulp and paper mill had reached capacity and were suffering from overload. The large growth in process control information and personal computers over the past few years was straining the abilities of existing coaxial and fiber optic systems to reliably transfer data. In addition, increased network complexity made troubleshooting the networks extremely difficult and time-consuming. This article discusses the design methods used to create a new fiber optic backbone to provide the data carrying capacity and reliability needed for the pulp and paper mill's computers and control systems. High-speed network technologies such as ATM (asynchronous transfer mode), FDDI (fiber distributed data interface) and fast Ethernet were compared for their suitability in industrial environments. The design also incorporated Ethernet switches so that the existing Ethernet networks could attach at minimal cost. These switches subdivided the original single large network into approximately 24 sub-networks. This division greatly increased the network's allowable traffic capacity and prevented problems in any one area from propagating throughout the mill, and thereby reduced network and process downtime.

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.

Performance analysis of FDDI LANs using numerical methods

Simulators are valuable tools; they help in understanding how complex systems will operate and perform without actually having to build a physical model to test. However, they often require extensive development and run times. This is especially true for many networks such as FDDI, where a large number of nodes and priority classes are involved. A high-level algorithm is presented to evaluate the performance characteristics of a token LAN. The goal of the research was to find a method for obtaining an estimate of the average access delay, and the average end-to-end delay of advanced token-ring networks. The FDDI (fibre distributed data interface) standards were used as the basis of a FFOL (FDDI follow-on LAN) solution. A method was developed that will generate exact results for such networks at low- to medium-load network environments. As the load level increases, the error rate of the estimate also increases; this however is monitored and can be used as a confidence measure for the results obtained. A symmetric multimedia environment is used in the model, with bimodal traffic consisting of short data packets, and longer video packets. A short introduction to the network setup and the examination of the method developed is presented in single and multinetwork environments. Specific network parameters were chosen for these experiments, but the method is easy to customise to other network parameters.

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.