631 research outputs found

    Optical fibre local area networks

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    IP and ATM - a position paper

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    This paper gives a technical overview of different networking technologies, such as the Internet, ATM. It describes different approaches of how to run IP on top of an ATM network, and assesses their potential to be used as an integrated services network

    Supporting distributed computation over wide area gigabit networks

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    The advent of high bandwidth fibre optic links that may be used over very large distances has lead to much research and development in the field of wide area gigabit networking. One problem that needs to be addressed is how loosely coupled distributed systems may be built over these links, allowing many computers worldwide to take part in complex calculations in order to solve "Grand Challenge" problems. The research conducted as part of this PhD has looked at the practicality of implementing a communication mechanism proposed by Craig Partridge called Late-binding Remote Procedure Calls (LbRPC). LbRPC is intended to export both code and data over the network to remote machines for evaluation, as opposed to traditional RPC mechanisms that only send parameters to pre-existing remote procedures. The ability to send code as well as data means that LbRPC requests can overcome one of the biggest problems in Wide Area Distributed Computer Systems (WADCS): the fixed latency due to the speed of light. As machines get faster, the fixed multi-millisecond round trip delay equates to ever increasing numbers of CPU cycles. For a WADCS to be efficient, programs should minimise the number of network transits they incur. By allowing the application programmer to export arbitrary code to the remote machine, this may be achieved. This research has looked at the feasibility of supporting secure exportation of arbitrary code and data in heterogeneous, loosely coupled, distributed computing environments. It has investigated techniques for making placement decisions for the code in cases where there are a large number of widely dispersed remote servers that could be used. The latter has resulted in the development of a novel prototype LbRPC using multicast IP for implicit placement and a sequenced, multi-packet saturation multicast transport protocol. These prototypes show that it is possible to export code and data to multiple remote hosts, thereby removing the need to perform complex and error prone explicit process placement decisions

    IP and ATM - current evolution for integrated services

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    Current and future applications make use of different technologies as voice, data, and video. Consequently network technologies need to support them. For many years, the ATM based Broadband-ISDN has generally been regarded as the ultimate networking technology, which can integrate voice, data, and video services. With the recent tremendous growth of the Internet and the reluctant deployment of public ATM networks, the future development of ATM seems to be less clear than it used to be. In the past IP provided (and was though to provide) only best effort services, thus, despite its world wide diffution, was not considered as a network solution for multimedia application. Currently many of the IETF working groups work on areas related to integrated services, and IP is also proposing itself as networking technology for supporting voice, data, and video services. This paper give a technical overview on the competing integrated services network solutions, such as IP, ATM and the different available and emerging technologies on how to run IP over ATM, and tries to identify their potential and shortcomings

    Multimedia Networks: Fundamentals and Future Directions

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    Multimedia has become an integral part of computing and communications environment, and networks are carrying ever-increasing volume of multimedia information. The main characteristics of multimedia information are high-volume and bursty traffic, with low tolerance to delay and delay variance. The legacy networks (designed in 70s and 80s) are not able to meet these requirements. Enhancements to the older networking technologies have been developed to convert these into multimedia networks. Enhancements to LANs include Switched Ethernet, Isochronous Ethernet, Fast Ethernet, 100VGAnyLAN, FDDI-II, and Synchronous FDDI. WAN options for multimedia networking include digital leased lines and ISDN. The Internet has revolutionized business and personal communications, but falls short of being a genuine multimedia network. To make the Internet capable of carrying multimedia traffic, new protocols such as MBone, ST-II, RTP, and RSVP have been developed. Internet2 is a new initiative that is aimed at overcoming the problems of throughput, delay and jitter encountered on the original Internet. One technology that was developed with multimedia networking as one of its main applications, is the Asynchronous Transfer Mode (ATM) technology. Upcoming Gigabit Ethernet technology will provide a path for upgrading current Ethernet networks into multimedia networks

    Telecommunication of stabilizing signals in power systems

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    Deregulation of the power industry has occurred at a rapid pace, opening some promising competition between suppliers. The result of this competition should be to the benefit of customers.;Telecommunication plays a crucial role in integrating systems and ensuring smooth operation by way of exchanging data and information between various systems that are responsible for monitoring and control of the grid. For example, a Power System Stabilizer (PSS) controller could be placed at one of the generators and requires remote measurements. All the communication schemes within the network generate delays that are characterized in this project using OPNET Modeler. OPNET Modeler is also used to characterize the number of dropped packets.;As a case study, we consider a two-area four-generator (2A4G) and explore the role of communication delay on system stability. Those delays play an important role in the design of a controller that can help the damping of electro-mechanical oscillations between interconnected synchronous generators and therefore maintain the system stability. The network statistics are then imported into Simulink in order to visualize the speed of the shaft w2 as a function of time. Additional communication options to the inter-area oscillation problem are offered at the end of the thesis (use of Virtual Private Network (VPN), use of fiber optic dedicated network, or the use of IPv6 protocol)

    Technology Directions for the 21st Century

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    New technologies will unleash the huge capacity of fiber-optic cable to meet growing demands for bandwidth. Companies will continue to replace private networks with public network bandwidth-on-demand. Although asynchronous transfer mode (ATM) is the transmission technology favored by many, its penetration will be slower than anticipated. Hybrid networks - e.g., a mix of ATM, frame relay, and fast Ethernet - may predominate, both as interim and long-term solutions, based on factors such as availability, interoperability, and cost. Telecommunications equipment and services prices will decrease further due to increased supply and more competition. Explosive Internet growth will continue, requiring additional backbone transmission capacity and enhanced protocols, but it is not clear who will fund the upgrade. Within ten years, space-based constellations of satellites in Low Earth orbit (LEO) will serve mobile users employing small, low-power terminals. 'Little LEO's' will provide packet transmission services and geo-position determination. 'Big LEO's' will function as global cellular telephone networks, with some planning to offer video and interactive multimedia services. Geosynchronous satellites also are proposed for mobile voice grade links and high-bandwidth services. NASA may benefit from resulting cost reductions in components, space hardware, launch services, and telecommunications services

    The Integration of Technology Theory and Business Analysis: A Pedagogical Framework for the Undergraduate MIS Course in Data Communications and Networking

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    One of the fundamental challenges of information systems education within a school of business is to integrate technology theory and business analysis. Information systems as an academic discipline must contain a theoretical component, for theory development is, after all, the essence of academia. However, model curricula for IS education (e.g., IS’2002.6) have been incorporating a growing number of applied, hands-on topics. This is especially true of the undergraduate course in data communications and networking (DCN). While we do not negate the value of a lab experience in network configuration, we posit that applied DCN topics can be effectively taught via the business case method as well. Toward this end, our article proposes a pedagogical framework. This type of framework can also be used in other Information Systems courses to maintain an appropriate balance between technology theory and business analysis
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