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Communications Magazine, IEEE

Issue 10 • Date Oct. 2002

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Displaying Results 1 - 16 of 16
  • Book Reviews

    Page(s): 20 - 22
    Save to Project icon | Request Permissions | PDF file iconPDF (267 KB)  
    Freely Available from IEEE
  • Perspectives - Global communities in IEEE standardization

    Page(s): 24
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    Freely Available from IEEE
  • Telecommunication Networks Security - Guest Editorial

    Page(s): 40 - 41
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    Freely Available from IEEE
  • Squeezing digital subscriber lines for more efficiency - guest editorial

    Page(s): 84 - 85
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    Freely Available from IEEE
  • Dynamic spectrum management for next-generation DSL systems

    Page(s): 101 - 109
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1346 KB) |  | HTML iconHTML  

    The performance of DSL systems is severely constrained by crosstalk due to the electromagnetic coupling among the multiple twisted pairs making up a phone cable. In order to reduce performance loss arising from crosstalk, DSL systems are currently designed under the assumption of worst-case crosstalk scenarios leading to overly conservative DSL deployments. This article presents a new paradigm for DSL system design, which takes into account the multi-user aspects of the DSL transmission environment. Dynamic spectrum management (DSM) departs from the current design philosophy by enabling transceivers to autonomously and dynamically optimize their communication settings with respect to both the channel and the transmissions of neighboring systems. Along with this distributed optimization, when an additional degree of coordination becomes available for future DSL deployment, DSM will allow even greater improvement in DSL performance. Implementations are readily applicable without causing any performance degradation to the existing DSLs under static spectrum management. After providing an overview of the DSM concept, this article reviews two practical DSM methods: iterative water-filling, an autonomous distributed power control method enabling great improvement in performance, which can be implemented through software options in some existing ADSL and VDSL systems; and vectored-DMT, a coordinated transmission/reception technique achieving crosstalk-free communication for DSL systems, which brings within reach the dream of providing universal Internet access at speeds close to 100 Mb/s to 500 m on 1-2 lines and beyond 1 km on 2-4 lines. DSM-capable DSL thus enables the broadband age. View full abstract»

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  • Understanding Internet traffic streams: dragonflies and tortoises

    Page(s): 110 - 117
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    We present the concept of network traffic streams and the ways they aggregate into flows through Internet links. We describe a method of measuring the size and lifetime of Internet streams, and use this method to characterize traffic distributions at two different sites. We find that although most streams (about 45 percent of them) are dragonflies, lasting less than 2 seconds, a significant number of streams have lifetimes of hours to days, and can carry a high proportion (50-60 percent) of the total bytes on a given link. We define tortoises as streams that last longer than 15 minutes. We point out that streams can be classified not only by lifetime (dragonflies and tortoises) but also by size (mice and elephants), and note that stream size and lifetime are independent dimensions. We submit that ISPs need to be aware of the distribution of Internet stream sizes, and the impact of the difference in behavior between short and long streams. In particular, any forwarding cache mechanisms in Internet routers must be able to cope with a high volume of short streams. In addition ISPs should realize that long-running streams can contribute a significant fraction of their packet and byte volumes-something they may not have allowed for when using traditional "flat rate user bandwidth consumption" approaches to provisioning and engineering. View full abstract»

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  • Channelized voice over digital subscriber line

    Page(s): 94 - 100
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    This article presents a promising voice over digital subscriber line (VoDSL) solution: an alternative method that uses physical layer transportation to provide channelized VoDSL (CVoDSL). This article also presents the advantages that the CVoDSL provides to the customers in terms of high-quality services and lower cost, and service providers in terms of market growth and success. It also offers a set of requirements, architectural design, and implementation scenarios that provide end-to-end solutions for CVoDSL. View full abstract»

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  • Traffic engineering with traditional IP routing protocols

    Page(s): 118 - 124
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    Traffic engineering involves adapting the routing of traffic to network conditions, with the joint goals of good user performance and efficient use of network resources. We describe an approach to intradomain traffic engineering that works within the existing deployed base of interior gateway protocols, such as Open Shortest Path First and Intermediate System-Intermediate System. We explain how to adapt the configuration of link weights, based on a networkwide view of the traffic and topology within a domain. In addition, we summarize the results of several studies of techniques for optimizing OSPF/IS-IS weights to the prevailing traffic. The article argues that traditional shortest path routing protocols are surprisingly effective for engineering the flow of traffic in large IP networks. View full abstract»

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  • Network intrusion and fault detection: a statistical anomaly approach

    Page(s): 76 - 82
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1063 KB) |  | HTML iconHTML  

    With the advent and explosive growth of the global Internet and electronic commerce environments, adaptive/automatic network/service intrusion and anomaly detection in wide area data networks and e-commerce infrastructures is fast gaining critical research and practical importance. We present and demonstrate the use of a general-purpose hierarchical multitier multiwindow statistical anomaly detection technology and system that operates automatically, adaptively, and proactively, and can be applied to various networking technologies, including both wired and wireless ad hoc networks. Our method uses statistical models and multivariate classifiers to detect anomalous network conditions. Some numerical results are also presented that demonstrate that our proposed methodology can reliably detect attacks with traffic anomaly intensity as low as 3-5 percent of the typical background traffic intensity, thus promising to generate an effective early warning. View full abstract»

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  • Local loop unbundling in the Italian network

    Page(s): 86 - 93
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    Unbundling consists of the possibility for a new operator to have special access to an incumbent's network infrastructure in order to provide value-added services without the necessity to duplicate the infrastructure itself. Local loop unbundling has received the most attention in Europe and in Italy. Most Italian operators are interested mainly in physical access to copper loop, which gives the opportunity to offer broadband services pervasively by exploiting the capabilities of xDSL technology. Technical issues to be faced in offering these services are severe and include loop qualification, interference evaluation, and shortage of available loops. Nonetheless, the Italian case, where more than 20 incoming operators are planning to deploy services on unbundled local loops, demonstrates that this opportunity can be a major driver for the development of the broadband services market. View full abstract»

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  • Multi-timescale Internet traffic engineering

    Page(s): 125 - 131
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    The Internet is a collection of packet-based hop-by-hop routed networks. Internet traffic engineering is the process of allocating resources to meet the performance requirements of users and operators for their traffic. Current mechanisms for doing so, exemplified by TCP's congestion control or the variety of packet marking disciplines, concentrate on allocating resources on a per-packet basis or at data timescales. This article motivates the need for traffic engineering in the Internet at other timescales, namely control and management timescales, and presents three mechanisms for this. It also presents a scenario to show how these mechanisms increase the flexibility of operators' service offerings and potentially also ease problems of Internet management. View full abstract»

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  • STEM: Secure Telephony Enabled Middlebox

    Page(s): 52 - 58
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    Dynamic applications, including IP telephony, have not seen wide acceptance within enterprises because of problems caused by the existing network infrastructure. Static elements, including firewalls and network address translation devices, are not capable of allowing dynamic applications to operate properly. The Secure Telephony Enabled Middlebox (STEM) architecture is an enhancement of the existing network design to remove the issues surrounding static devices. The architecture incorporates an improved firewall that can interpret and utilize information in the application layer of packets to ensure proper functionality. In addition to allowing dynamic applications to function normally, the STEM architecture also incorporates several detection and response mechanisms for well-known network-based vulnerabilities. This article describes the key components of the architecture with respect to the SIP protocol. View full abstract»

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  • Defending against flooding-based distributed denial-of-service attacks: a tutorial

    Page(s): 42 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1940 KB) |  | HTML iconHTML  

    Flooding-based distributed denial-of-service (DDoS) attack presents a very serious threat to the stability of the Internet. In a typical DDoS attack, a large number of compromised hosts are amassed to send useless packets to jam a victim, or its Internet connection, or both. In the last two years, it was discovered that DDoS attack methods and tools are becoming more sophisticated, effective, and also more difficult to trace to the real attackers. On the defense side, current technologies are still unable to withstand large-scale attacks. The main purpose of this article is therefore twofold. The first one is to describe various DDoS attack methods, and to present a systematic review and evaluation of the existing defense mechanisms. The second is to discuss a longer-term solution, dubbed the Internet-firewall approach, that attempts to intercept attack packets in the Internet core, well before reaching the victim. View full abstract»

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  • Routing security in wireless ad hoc networks

    Page(s): 70 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB) |  | HTML iconHTML  

    A mobile ad hoc network consists of a collection of wireless mobile nodes that are capable of communicating with each other without the use of a network infrastructure or any centralized administration. MANET is an emerging research area with practical applications. However, wireless MANET is particularly vulnerable due to its fundamental characteristics, such as open medium, dynamic topology, distributed cooperation, and constrained capability. Routing plays an important role in the security of the entire network. In general, routing security in wireless MANETs appears to be a problem that is not trivial to solve. In this article we study the routing security issues of MANETs, and analyze in detail one type of attack-the "black hole" problem-that can easily be employed against the MANETs. We also propose a solution for the black hole problem for ad hoc on-demand distance vector routing protocol. View full abstract»

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  • Securing the Internet routing infrastructure

    Page(s): 60 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1266 KB) |  | HTML iconHTML  

    The unprecedented growth of the Internet over the last years, and the expectation of an even faster increase in the numbers of users and networked systems, resulted in the Internet assuming its position as a mass communication medium. At the same time, the emergence of an increasingly large number of application areas and the evolution of the networking technology suggest that in the near future the Internet may become the single integrated communication infrastructure. However, as the dependence on the networking infrastructure grows, its security becomes a major concern, in light of the increased attempt to compromise the infrastructure. In particular, the routing operation is a highly visible target that must be shielded against a wide range of attacks. The injection of false routing information can easily degrade network performance, or even cause denial of service for a large number of hosts and networks over a long period of time. Different approaches have been proposed to secure the routing protocols, with a variety of countermeasures, which, nonetheless, have not eradicated the vulnerability of the routing infrastructure. In this article, we survey the up-to-date secure routing schemes. that appeared over the last few years. Our critical point of view and thorough review of the literature are an attempt to identify directions for future research on an indeed difficult and still largely open problem. View full abstract»

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  • Expanding the wireless universe: EU research on the move

    Page(s): 132 - 140
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    This article provides an overview of the activities currently carried out under the IST research program of the European Commission, in the area of mobile and wireless communications and satellite systems. The research orientations specific to wireless communications are described in detail, with reference to the projects active in each area, defining a possible roadmap for the evolution of mobile communications systems beyond UMTS. View full abstract»

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Aims & Scope

IEEE Communications Magazine covers all areas of communications such as lightwave telecommunications, high-speed data communications, personal communications systems (PCS), ISDN, and more.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Sean Moore
Centripetal Networks