420 research outputs found

    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

    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

    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

    Software Defined Networks based Smart Grid Communication: A Comprehensive Survey

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    The current power grid is no longer a feasible solution due to ever-increasing user demand of electricity, old infrastructure, and reliability issues and thus require transformation to a better grid a.k.a., smart grid (SG). The key features that distinguish SG from the conventional electrical power grid are its capability to perform two-way communication, demand side management, and real time pricing. Despite all these advantages that SG will bring, there are certain issues which are specific to SG communication system. For instance, network management of current SG systems is complex, time consuming, and done manually. Moreover, SG communication (SGC) system is built on different vendor specific devices and protocols. Therefore, the current SG systems are not protocol independent, thus leading to interoperability issue. Software defined network (SDN) has been proposed to monitor and manage the communication networks globally. This article serves as a comprehensive survey on SDN-based SGC. In this article, we first discuss taxonomy of advantages of SDNbased SGC.We then discuss SDN-based SGC architectures, along with case studies. Our article provides an in-depth discussion on routing schemes for SDN-based SGC. We also provide detailed survey of security and privacy schemes applied to SDN-based SGC. We furthermore present challenges, open issues, and future research directions related to SDN-based SGC.Comment: Accepte

    Providing guaranteed QoS in the hose-modeled VPN

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    With the development of the Internet, Internet service providers (ISPs) are required to offer revenue-generating and value-added services instead of only providing bandwidth and access services. Virtual Private Network (VPN) is one of the most important value-added services for ISPs. The classical VPN service is provided by implementing layer 2 technologies, either Frame Relay (FR) or Asynchronous Transfer Mode (ATM). With FR or ATM, virtual circuits are created before data delivery. Since the bandwidth and buffers are reserved, the QoS requirements can be naturally guaranteed. In the past few years, layer 3 VPN technologies are widely deployed due to the desirable performance in terms of flexibility, scalability and simplicity. Layer 3 VPNs are built upon IP tunnels, e.g., by using PPTP, L2TP or IPSec. Since IP is best-of-effort in nature, the QoS requirement cannot be guaranteed in layer 3 VPNs. Actually, layer 3 VPN service can only provide secure connectivity, i.e., protecting and authenticating IP packets between gateways or hosts in a VPN. Without doubt, with more applications on voice, audio and video being used in the Internet, the provision of QoS is one of the most important parts of the emerging services provided by ISPs. An intriguing question is: Is it possible to obtain the best of both layer 2 and 3 VPN? Is it possible to provide guaranteed or predictable QoS, as in layer 2 VPNs, while maintaining the flexibility and simplicity in layer 3 VPN? This question is the starting point of this study. The recently proposed hose model for VPN possesses desirable properties in terms of flexibility, scalability and multiplexing gain. However, the classic fair bandwidth allocation schemes and weighted fair queuing schemes raise the issue of low overall utilization in this model. A new fluid model for provider-provisioned virtual private network (PPVPN) is proposed in this dissertation. Based on the proposed model, an idealized fluid bandwidth allocation scheme is developed. This scheme is proven, analytically, to have the following properties: 1) maximize the overall throughput of the VPN without compromising fairness; 2) provide a mechanism that enables the VPN customers to allocate the bandwidth according to their requirements by assigning different weights to different hose flows, and thus obtain the predictable QoS performance; and 3) improve the overall throughput of the ISPs\u27 network. To approximate the idealized fluid scheme in the real world, the 2-dimensional deficit round robin (2-D DRR and 2-D DRR+) schemes are proposed. The integration of the proposed schemes with the best-effort traffic within the framework of virtual-router-based VPN is also investigated. The 2-D DRR and 2-D DER-+ schemes can be extended to multi-dimensional schemes to be employed in those applications which require a hierarchical scheduling architecture. To enhance the scalability, a more scalable non-per-flow-based scheme for output queued switches is developed as well, and the integration of this scheme within the framework of the MPLS VPN and applications for multicasting traffics is discussed. The performance and properties of these schemes are analyzed

    On packet switch design

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    Monitoring multicast traffic in heterogeneous networks

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    Estágio realizado no INESC - Porto e orientado pelo Prof. Doutor Ricardo MorlaTese de mestrado integrado. Engenharia Electrotécnica e de Computadores - Major Telecomunicações. Faculdade de Engenharia. Universidade do Porto. 200

    An adaptive algorithm for Internet multimedia delivery in a DiffServ environment.

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    To meet the Quality of Service (QoS) requirements of multimedia applications and to reduce the network congestion, several service models and mechanisms have been proposed. Among these, Differentiated Service (DiffServ) architecture has been considered as a scalable and flexible QoS architecture for the Internet. DiffServ provides class-based QoS guarantees. Applications in different classes receive different QoS and are priced differently. If network congestion occurs, DiffServ may not be able to guarantee the QoS for the application. Thus, the QoS may not reflect the price paid for the service. A problem of considerable economic and research importance is how to achieve a good price and quality tradeoff even at times of congestion. This thesis presents an Adaptive Class Switching Algorithm (ACSA) which intends to provide good quality with good price for real-time multimedia applications in a DiffServ environment. The ACSA algorithm combines the techniques of Real-time Transport Protocol (RTP), DiffServ, and Adaptation together. It also takes both QoS and price into account to provide users a good QoS with a good price. The algorithm dynamically selects the most suitable class based on both the QoS feedback received and the highest user utility. The user utility is a function of quality, price, and the weight which reflects the relative sensitivity to quality and price. The class with the highest user utility is the class that provides the best quality and price tradeoff. The QoS feedback is conveyed by RTP\u27s Control Protocol (RTCP) Receiver Reports. The results of simulation demonstrate that ACSA can react fast to the current class state in the network and reflects the best QoS and price tradeoff. It always seeks to find a class which provides the highest user utility except when the Internet is congested and the required QoS in all classes can not be satisfied. If this happens, the real-time multimedia flow chooses Best-Effort class with no payment. (Abstract shortened by UMI.) Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .F46. Source: Masters Abstracts International, Volume: 44-01, page: 0389. Thesis (M.Sc.)--University of Windsor (Canada), 2005
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