623 research outputs found

    Low Cost Quality of Service Multicast Routing in High Speed Networks

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    Many of the services envisaged for high speed networks, such as B-ISDN/ATM, will support real-time applications with large numbers of users. Examples of these types of application range from those used by closed groups, such as private video meetings or conferences, where all participants must be known to the sender, to applications used by open groups, such as video lectures, where partcipants need not be known by the sender. These types of application will require high volumes of network resources in addition to the real-time delay constraints on data delivery. For these reasons, several multicast routing heuristics have been proposed to support both interactive and distribution multimedia services, in high speed networks. The objective of such heuristics is to minimise the multicast tree cost while maintaining a real-time bound on delay. Previous evaluation work has compared the relative average performance of some of these heuristics and concludes that they are generally efficient, although some perform better for small multicast groups and others perform better for larger groups. Firstly, we present a detailed analysis and evaluation of some of these heuristics which illustrates that in some situations their average performance is reversed; a heuristic that in general produces efficient solutions for small multicasts may sometimes produce a more efficient solution for a particular large multicast, in a specific network. Also, in a limited number of cases using Dijkstra's algorithm produces the best result. We conclude that the efficiency of a heuristic solution depends on the topology of both the network and the multicast, and that it is difficult to predict. Because of this unpredictability we propose the integration of two heuristics with Dijkstra's shortest path tree algorithm to produce a hybrid that consistently generates efficient multicast solutions for all possible multicast groups in any network. These heuristics are based on Dijkstra's algorithm which maintains acceptable time complexity for the hybrid, and they rarely produce inefficient solutions for the same network/multicast. The resulting performance attained is generally good and in the rare worst cases is that of the shortest path tree. The performance of our hybrid is supported by our evaluation results. Secondly, we examine the stability of multicast trees where multicast group membership is dynamic. We conclude that, in general, the more efficient the solution of a heuristic is, the less stable the multicast tree will be as multicast group membership changes. For this reason, while the hybrid solution we propose might be suitable for use with closed user group multicasts, which are likely to be stable, we need a different approach for open user group multicasting, where group membership may be highly volatile. We propose an extension to an existing heuristic that ensures multicast tree stability where multicast group membership is dynamic. Although this extension decreases the efficiency of the heuristics solutions, its performance is significantly better than that of the worst case, a shortest path tree. Finally, we consider how we might apply the hybrid and the extended heuristic in current and future multicast routing protocols for the Internet and for ATM Networks.

    ISDN3: The next generation networks

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    Two generations of Integrated Services Digital Network (ISDN), namely ISDN1 and ISDN2, have been developed in the last century. In our view, the convergence of ATM, Internet and active networks will form the basis for the next generation networks called ISDN3. In this paper, we first review ISDN1 and ISDN2 as well as the Internet and active networks. We then discuss some fundamental questions related to the design of ISDN3. Finally, we compare ISDN3 with ISDN1 and ISDN2, and outline what ISDN3 might look like.published_or_final_versio

    Quality of Service over Specific Link Layers: state of the art report

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    The Integrated Services concept is proposed as an enhancement to the current Internet architecture, to provide a better Quality of Service (QoS) than that provided by the traditional Best-Effort service. The features of the Integrated Services are explained in this report. To support Integrated Services, certain requirements are posed on the underlying link layer. These requirements are studied by the Integrated Services over Specific Link Layers (ISSLL) IETF working group. The status of this ongoing research is reported in this document. To be more specific, the solutions to provide Integrated Services over ATM, IEEE 802 LAN technologies and low-bitrate links are evaluated in detail. The ISSLL working group has not yet studied the requirements, that are posed on the underlying link layer, when this link layer is wireless. Therefore, this state of the art report is extended with an identification of the requirements that are posed on the underlying wireless link, to provide differentiated Quality of Service

    IP and ATM integration: A New paradigm in multi-service internetworking

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    ATM is a widespread technology adopted by many to support advanced data communication, in particular efficient Internet services provision. The expected challenges of multimedia communication together with the increasing massive utilization of IP-based applications urgently require redesign of networking solutions in terms of both new functionalities and enhanced performance. However, the networking context is affected by so many changes, and to some extent chaotic growth, that any approach based on a structured and complex top-down architecture is unlikely to be applicable. Instead, an approach based on finding out the best match between realistic service requirements and the pragmatic, intelligent use of technical opportunities made available by the product market seems more appropriate. By following this approach, innovations and improvements can be introduced at different times, not necessarily complying with each other according to a coherent overall design. With the aim of pursuing feasible innovations in the different networking aspects, we look at both IP and ATM internetworking in order to investigating a few of the most crucial topics/ issues related to the IP and ATM integration perspective. This research would also address various means of internetworking the Internet Protocol (IP) and Asynchronous Transfer Mode (ATM) with an objective of identifying the best possible means of delivering Quality of Service (QoS) requirements for multi-service applications, exploiting the meritorious features that IP and ATM have to offer. Although IP and ATM often have been viewed as competitors, their complementary strengths and limitations from a natural alliance that combines the best aspects of both the technologies. For instance, one limitation of ATM networks has been the relatively large gap between the speed of the network paths and the control operations needed to configure those data paths to meet changing user needs. IP\u27s greatest strength, on the other hand, is the inherent flexibility and its capacity to adapt rapidly to changing conditions. These complementary strengths and limitations make it natural to combine IP with ATM to obtain the best that each has to offer. Over time many models and architectures have evolved for IP/ATM internetworking and they have impacted the fundamental thinking in internetworking IP and ATM. These technologies, architectures, models and implementations will be reviewed in greater detail in addressing possible issues in integrating these architectures s in a multi-service, enterprise network. The objective being to make recommendations as to the best means of interworking the two in exploiting the salient features of one another to provide a faster, reliable, scalable, robust, QoS aware network in the most economical manner. How IP will be carried over ATM when a commercial worldwide ATM network is deployed is not addressed and the details of such a network still remain in a state of flux to specify anything concrete. Our research findings culminated with a strong recommendation that the best model to adopt, in light of the impending integrated service requirements of future multi-service environments, is an ATM core with IP at the edges to realize the best of both technologies in delivering QoS guarantees in a seamless manner to any node in the enterprise

    Design and evaluation of a connection management mechanism for an ATM-based connectionless service

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    The Asynchronous Transfer Mode (ATM) has been developed as a connection-oriented technique for the transfer of fixed-size cells over high-speed networks. Many applications, however, require a connectionless network service. In order to provide such a technique, one can built a connectionless service on top of the connection-oriented service. In doing so, the issue of connection management comes into play. In this paper we propose a new connection management mechanism that provides for low bandwidth usage (as compared to a permanent connection) and low delays (as compared to a connection-per-packet approach). We model the new mechanism under two workload scenarios: an ordinary Poisson process and an interrupted Poisson process. We use Markovian techniques as well as matrix-geometric methods to evaluate the new connection management mechanism. From the evaluations it turns out that the proposed mechanism is superior to older approaches (which can be seen as limiting cases)

    A high speed fault-tolerant multimedia network and connectionless gateway for ATM networks.

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    by Patrick Lam Sze Fan.Thesis (M.Phil.)--Chinese University of Hong Kong, 1997.Includes bibliographical references (leaves 163-[170]).Chapter 1 --- Introduction --- p.1Chapter 2 --- Fault-tolerant CUM LAUDE NET --- p.7Chapter 2.1 --- Overview of CUM LAUDE NET --- p.7Chapter 2.2 --- Network architecture of CUM LAUDE NET --- p.8Chapter 2.3 --- Design of Router-node --- p.10Chapter 2.3.1 --- Architecture of the Router-node --- p.10Chapter 2.3.2 --- Buffers Arrangement of the Router-node --- p.12Chapter 2.3.3 --- Buffer transmission policies --- p.13Chapter 2.4 --- Protocols of CUM LAUDE NET --- p.14Chapter 2.5 --- Frame Format of CUM LAUDE NET --- p.15Chapter 2.6 --- Fault-tolerant (FT) and Auto-healing (AH) algorithms --- p.16Chapter 2.6.1 --- Overview of the algorithms --- p.16Chapter 2.6.2 --- Network Failure Scenarios --- p.18Chapter 2.6.3 --- Design and Implementation of the Fault Tolerant Algorithm --- p.19Chapter 2.6.4 --- Design and Implementation of the Auto Healing Algorithm --- p.26Chapter 2.6.5 --- Network Management Signals and Restoration Times --- p.27Chapter 2.6.6 --- Comparison of fault-tolerance features of other networks with the CUM LAUDE NET --- p.31Chapter 2.7 --- Chapter Summary --- p.31Chapter 3 --- Overview of the Asynchronous Transfer Mode (ATM) --- p.33Chapter 3.1 --- Introduction --- p.33Chapter 3.2 --- ATM Network Interfaces --- p.34Chapter 3.3 --- ATM Virtual Connections --- p.35Chapter 3.4 --- ATM Cell Format --- p.36Chapter 3.5 --- ATM Address Formats --- p.36Chapter 3.6 --- ATM Protocol Reference Model --- p.38Chapter 3.6.1 --- The ATM Layer --- p.39Chapter 3.6.2 --- The ATM Adaptation Layer --- p.39Chapter 3.7 --- ATM Signalling --- p.44Chapter 3.7.1 --- ATM Signalling Messages and Call Setup Procedures --- p.45Chapter 3.8 --- Interim Local Management Interface (ILMI) --- p.47Chapter 4 --- Issues of Connectionless Gateway --- p.49Chapter 4.1 --- Introduction --- p.49Chapter 4.2 --- The Issues --- p.50Chapter 4.3 --- ATM Internetworking --- p.51Chapter 4.3.1 --- LAN Emulation --- p.52Chapter 4.3.2 --- IP over ATM --- p.53Chapter 4.3.3 --- Comparing IP over ATM and LAN Emulation --- p.59Chapter 4.4 --- Connection Management --- p.61Chapter 4.4.1 --- The Indirect Approach --- p.62Chapter 4.4.2 --- The Direct Approach --- p.63Chapter 4.4.3 --- Comparing the two approaches --- p.64Chapter 4.5 --- Protocol Conversion --- p.65Chapter 4.5.1 --- Selection of Protocol Converter --- p.68Chapter 4.6 --- Packet Forwarding Modes --- p.68Chapter 4.7 --- Bandwidth Assignment --- p.70Chapter 4.7.1 --- Bandwidth Reservation --- p.71Chapter 4.7.2 --- Fast Bandwidth Reservation --- p.72Chapter 4.7.3 --- Bandwidth Advertising --- p.72Chapter 4.7.4 --- Bandwidth Advertising with Cell Drop Detection --- p.73Chapter 4.7.5 --- Bandwidth Allocation on Source Demand --- p.73Chapter 4.7.6 --- The Common Problems --- p.74Chapter 5 --- Design and Implementation of the Connectionless Gateway --- p.77Chapter 5.1 --- Introduction --- p.77Chapter 5.1.1 --- Functions Definition of Connectionless Gateway --- p.79Chapter 5.2 --- Hardware Architecture of the Connectionless Gateway --- p.79Chapter 5.2.1 --- Imposed Limitations --- p.82Chapter 5.3 --- Software Architecture of the Connectionless Gateway --- p.83Chapter 5.3.1 --- TCP/IP Internals --- p.84Chapter 5.3.2 --- ATM on Linux --- p.85Chapter 5.4 --- Network Architecture --- p.88Chapter 5.4.1 --- IP Addresses Assignment --- p.90Chapter 5.5 --- Internal Structure of Connectionless Gateway --- p.90Chapter 5.5.1 --- Protocol Stacks of the Gateway --- p.90Chapter 5.5.2 --- Gateway Operation by Example --- p.93Chapter 5.5.3 --- Routing Table Maintenance --- p.97Chapter 5.6 --- Additional Features --- p.105Chapter 5.6.1 --- Priority Output Queues System --- p.105Chapter 5.6.2 --- Gateway Performance Monitor --- p.112Chapter 5.7 --- Setup an Operational ATM LAN --- p.117Chapter 5.7.1 --- SVC Connections --- p.117Chapter 5.7.2 --- PVC Connections --- p.119Chapter 5.8 --- Application of the Connectionless Gateway --- p.120Chapter 6 --- Performance Measurement of the Connectionless Gateway --- p.121Chapter 6.1 --- Introduction --- p.121Chapter 6.2 --- Experimental Setup --- p.121Chapter 6.3 --- Measurement Tools of the Experiments --- p.123Chapter 6.4 --- Descriptions of the Experiments --- p.124Chapter 6.4.1 --- Log Files --- p.125Chapter 6.5 --- UDP Control Rate Test --- p.126Chapter 6.5.1 --- Results and analysis of the UDP Control Rate Test --- p.127Chapter 6.6 --- UDP Maximum Rate Test --- p.138Chapter 6.6.1 --- Results and analysis of the UDP Maximum Rate Test --- p.138Chapter 6.7 --- TCP Maximum Rate Test --- p.140Chapter 6.7.1 --- Results and analysis of the TCP Maximum Rate Test --- p.140Chapter 6.8 --- Request/Response Test --- p.144Chapter 6.8.1 --- Results and analysis of the Request/Response Test --- p.144Chapter 6.9 --- Priority Queue System Verification Test --- p.149Chapter 6.9.1 --- Results and analysis of the Priority Queue System Verifi- cation Test --- p.150Chapter 6.10 --- Other Observations --- p.153Chapter 6.11 --- Solutions to Improve the Performance --- p.154Chapter 6.12 --- Future Development --- p.157Chapter 7 --- Conclusion --- p.158Bibliography --- p.163A List of Publications --- p.17

    DSL-based triple-play services

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    This research examines the triple play service based on the ADSL technology. The voice over IP will be checked and combined with the internet data by two monitoring programs in order to examine the performance that this service offers and then will be compared with the usual method of internet connection.This research examines the triple play service based on the ADSL technology. The voice over IP will be checked and combined with the internet data by two monitoring programs in order to examine the performance that this service offers and then will be compared with the usual method of internet connection.
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