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Selected Areas in Communications, IEEE Journal on

Issue 6 • Date Aug. 2003

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Displaying Results 1 - 10 of 10
  • Guest editorial internet and WWW measurement, mapping, and modeling

    Publication Year: 2003 , Page(s): 877 - 878
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    Freely Available from IEEE
  • Building low-diameter peer-to-peer networks

    Publication Year: 2003 , Page(s): 995 - 1002
    Cited by:  Papers (41)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB) |  | HTML iconHTML  

    Peer-to-peer (P2P) computing has emerged as a significant paradigm for providing distributed services, in particular search and data sharing. Current P2P networks (e.g., Gnutella) are constructed by participants following their own uncoordinated (and often whimsical) protocols; they consequently suffer from frequent network overload and partitioning into disconnected pieces separated by choke points with inadequate bandwidth. We propose a protocol for participants to build P2P networks in a distributed fashion, and prove that it results in connected networks of constant degree and logarithmic diameter. These properties are crucial for efficient search and data exchange. An important feature of our protocol is that it operates without global knowledge of all the nodes in the network. View full abstract»

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  • Tearing down the Internet

    Publication Year: 2003 , Page(s): 949 - 960
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1066 KB) |  | HTML iconHTML  

    Recent advances in scale-free networks have claimed that their topologies are very weak against attacks. The inhomogeneous connectivity distribution of large-scale current communication networks, such as the Internet, could be exploited by evil hackers in order to damage these systems. However, there have not been many studies on the approaches and consequences of such targeted attacks. In this paper, we propose an in-depth study of the Internet topology robustness to attacks at the network layer. Several attacking techniques are presented, as well as their effects on the connectivity of the Internet. We show that although the removal of a small fraction of nodes (less than 10%) can damage the Internet connectivity, such a node removal attack would still require a large amount of work to be carried out. To achieve this, we study in detail the interactions between the intradomain and interdomain levels of the Internet through the use of an overlay. View full abstract»

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  • Efficient and adaptive Web replication using content clustering

    Publication Year: 2003 , Page(s): 979 - 994
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1232 KB) |  | HTML iconHTML  

    Recently, there has been an increasing deployment of content distribution networks (CDNs) that offer hosting services to Web content providers. In this paper, we first compare the uncooperative pulling of Web contents used by commercial CDNs with the cooperative pushing. Our results show that the latter can achieve comparable users' perceived performance with only 4%-5% of replication and update traffic compared with the former scheme. Therefore, we explore how to efficiently push content to CDN nodes. Using trace-driven simulation, we show that replicating content in units of URLs can yield 60%-70% reduction in clients' latency, compared with replicating in units of Websites. However, it is very expensive to perform such a fine-grained replication. To address this issue, we propose to replicate content in units of clusters, each containing objects which are likely to be requested by clients that are topologically close. To this end, we describe three clustering techniques and use various topologies and several large Web server traces to evaluate their performance. Our results show that the cluster-based replication achieves performance close to that of the URL-based scheme, but only at 1%-2% of computation and management cost. In addition, by adjusting the number of clusters, we can smoothly trade off management and computation cost for better client performance. To adapt to changes in users' access patterns, we also explore incremental clustering that adaptively adds new documents to the existing content clusters. We examine both offline and online incremental clustering, where the former assumes access history is available while the latter predicts access pattern based on the hyperlink structure. Our results show that the offline clustering yields performance close to that of the complete re-clustering at much lower overhead. The online incremental clustering and replication cut down the retrieval cost by 4.6 times compared with random and by 8 times compared with no replication. Therefore it is especially useful to improve document availability during flash crowds. View full abstract»

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  • Predicting and bypassing end-to-end Internet service degradations

    Publication Year: 2003 , Page(s): 961 - 978
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (998 KB) |  | HTML iconHTML  

    We study the patterns and predictability of Internet end-to-end service degradations, where a degradation is a significant deviation of the round-trip time (RTT) between a client and a server. We use simultaneous RTT measurements collected from several locations to a large representative set of Web sites and study the duration and extent of degradations. We combine these measurements with border gateway protocol cluster information to learn on the location of the cause. We evaluate a number of predictors based upon hidden Markov models and Markov models. Predictors typically exhibit a tradeoff between two types of errors, false positives (incorrect degradation prediction) and false negatives (a degradation is not predicted). The costs of these error types is application dependent, but we capture the entire spectrum using a precision versus recall tradeoff. Using this methodology, we learn what information is most valuable for prediction (recency versus quantity of past measurements). Surprisingly, we also conclude that predictors that utilize history in a very simple way perform as well as more sophisticated ones. One important application of prediction is gateway selection, which is applicable when a local-area network is connected through multiple gateways to one or several Internet service provider. Gateway selection can boost reliability and survivability by selecting for each connection the (hopefully) best gateway. We show that gateway selection using our predictors can reduce the degradations to half of that obtained by routing all the connections through the best gateway. View full abstract»

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  • On the geographic location of Internet resources

    Publication Year: 2003 , Page(s): 934 - 948
    Cited by:  Papers (28)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (981 KB) |  | HTML iconHTML  

    One relatively unexplored question about the Internet's physical structure concerns the geographical location of its components: routers, links, and autonomous systems (ASes). We study this question using two large inventories of Internet routers and links, collected by different methods and about two years apart. We first map each router to its geographical location using two different state-of-the-art tools. We then study the relationship between router location and population density; between geographic distance and link density; and between the size and geographic extent of ASes. Our findings are consistent across the two datasets and both mapping methods. First, as expected, router density per person varies widely over different economic regions; however, in economically homogeneous regions, router density shows a strong superlinear relationship to population density. Second, the probability that two routers are directly connected is strongly dependent on distance; our data is consistent with a model in which a majority (up to 75%-95%) of link formation is based on geographical distance (as in the Waxman (1988) topology generation method). Finally, we find that ASes show high variability in geographic size, which is correlated with other measures of AS size (degree and number of interfaces). Among small to medium ASes, ASes show wide variability in their geographic dispersal; however, all ASes exceeding a certain threshold in size are maximally dispersed geographically. These findings have many implications for the next generation of topology generators, which we envisage as producing router-level graphs annotated with attributes such as link latencies, AS identifiers, and geographical locations. View full abstract»

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  • Measurement and analysis of single-hop delay on an IP backbone network

    Publication Year: 2003 , Page(s): 908 - 921
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB) |  | HTML iconHTML  

    We measure and analyze the single-hop packet delay through operational routers in the Sprint Internet protocol (IP) backbone network. After presenting our delay measurements through a single router for OC-3 and OC-12 link speeds, we propose a methodology to identify the factors contributing to single-hop delay. In addition to packet processing, transmission, and queueing delay at the output link, we observe the presence of very large delays that cannot be explained within the context of a first-in first-out output queue model. We isolate and analyze these outliers. Results indicate that there is very little queueing taking place in Sprint's backbone. As link speeds increase, transmission delay decreases and the dominant part of single-hop delay is packet processing time. We show that if a packet is received and transmitted on the same linecard, it experiences less than 20 μs of delay. If the packet is transmitted across the switch fabric, its delay doubles in magnitude. We observe that processing due to IP options results in single-hop delays in the order of milliseconds. Milliseconds of delay may also be experienced by packets that do not carry IP options. We attribute those delays to router idiosyncratic behavior that affects less than 1% of the packets. Finally, we show that the queueing delay distribution is long-tailed and can be approximated with a Weibull distribution with the scale parameter a=0.5 and the shape parameter b=0.6 to 0.82. View full abstract»

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  • Measuring the size of the Internet via importance sampling

    Publication Year: 2003 , Page(s): 922 - 933
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (854 KB) |  | HTML iconHTML  

    Measuring the size of the Internet via Monte Carlo sampling requires probing a large portion of the Internet protocol (IP) address space to obtain an accurate estimate. However, the distribution of information servers on the Internet is highly nonuniform over the IP address space. This allows us to design probing strategies based on importance sampling for measuring the prevalence of an information service on the Internet that are significantly more effective than strategies relying on Monte Carlo sampling. We present thorough analysis of our strategies together with accurate estimates for the current size of the Internet Protocol Version 4 (IPv4) Internet as measured by the number of publicly accessible web servers and FTP servers. View full abstract»

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  • Evaluation and characterization of available bandwidth probing techniques

    Publication Year: 2003 , Page(s): 879 - 894
    Cited by:  Papers (191)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (929 KB) |  | HTML iconHTML  

    The packet pair mechanism has been shown to be a reliable method to measure the bottleneck link capacity on a network path, but its use for measuring available bandwidth is more challenging. In this paper, we use modeling, measurements, and simulations to better characterize the interaction between probing packets and the competing network traffic. We first construct a simple model to understand how competing traffic changes the probing packet gap for a single-hop network. The gap model shows that the initial probing gap is a critical parameter when using packet pairs to estimate available bandwidth. Based on this insight, we present two available bandwidth measurement techniques, the initial gap increasing (IGI) method and the packet transmission rate (PTR) method. We use extensive Internet measurements to show that these techniques estimate available bandwidth faster than existing techniques such as Pathload, with comparable accuracy. Finally, using both Internet measurements and ns simulations, we explore how the measurement accuracy of active probing is affected by factors such as the probing packet size, the length of probing packet train, and the competing traffic on links other than the tight link. View full abstract»

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  • A nonstationary traffic train model for fine scale inference from coarse scale counts

    Publication Year: 2003 , Page(s): 895 - 907
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (961 KB) |  | HTML iconHTML  

    The self-similarity of network traffic has been convincingly established based on detailed packet traces. This fundamental result promises the possibility of solving on-line and off-line traffic engineering problems using easily collectible coarse time-scale data, such as simple network management protocol measurements. This paper proposes a statistical model that supports predicting fine time-scale behavior of network traffic from coarse time-scale aggregate measurements. The model generalizes the commonly used fractional Gaussian noise process in two important ways: (1) it accommodates the recurring daily load patterns commonly observed on backbone links and (2) features of long range dependence and self-similarity are modeled only at fine time scales and are progressively damped as the time period increases. Using the data we collected on the Chinese Education and Research Network, we demonstrate that the proposed model fits 5-min data and generates 10-s aggregates that are similar to actual 10-s data. View full abstract»

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Aims & Scope

IEEE Journal on Selected Areas in Communications focuses on all telecommunications, including telephone, telegraphy, facsimile, and point-to-point television, by electromagnetic propagation.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Muriel Médard
MIT