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44
An analysis of Internet chat systems
- In IMC ’03: Proceedings of the 3rd ACM SIGCOMM conference on Internet measurement
, 2003
"... In our quest to better understand network tra#c dynamics, we examine Internet chat systems. Although chat as an application does not contribute huge amounts of tra#c, chat systems are known to be habit-forming. This implies that catering to such users can be a promising way of attracting them, espec ..."
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Cited by 68 (2 self)
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In our quest to better understand network tra#c dynamics, we examine Internet chat systems. Although chat as an application does not contribute huge amounts of tra#c, chat systems are known to be habit-forming. This implies that catering to such users can be a promising way of attracting them, especially in low bandwidth environments such as wireless networks.
Nearly insensitive bounds on SMART scheduling
- In Proc. of ACM Sigmetrics
, 2005
"... We define the class of SMART scheduling policies. These are policies that bias towards jobs with small remaining service times, jobs with small original sizes, or both, with the motivation of minimizing mean response time and/or mean slowdown. Examples of SMART policies include PSJF, SRPT, and hybri ..."
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Cited by 30 (17 self)
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We define the class of SMART scheduling policies. These are policies that bias towards jobs with small remaining service times, jobs with small original sizes, or both, with the motivation of minimizing mean response time and/or mean slowdown. Examples of SMART policies include PSJF, SRPT, and hybrid policies such as RS (which biases according to the product of the remaining size and the original size of a job). For many policies in the SMART class, the mean response time and mean slowdown are not known or have complex representations involving multiple nested integrals, making evaluation difficult. In this work, we prove three main results. First, for all policies in the SMART class, we prove simple upper and lower bounds on mean response time. Second, we show that all policies in the SMART class, surprisingly, have very similar mean response times. Third, we show that the response times of SMART policies are largely insensitive to the variability of the job size distribution. In particular, we focus on the SRPT and PSJF policies and prove insensitive bounds in these cases.
Characterizing Network Traffic in a Cluster-based, Multi-tier Data Center
- In Proceedings of the 27th International Conference on Distributed Computing Systems (ICDCS
"... With the increasing use of various Web-based services, design of high performance, scalable and dependable data centers has become a critical issue. Recent studies show that a clustered, multi-tier architecture is a cost-effective approach to design such servers. Since these servers are highly distr ..."
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Cited by 27 (4 self)
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With the increasing use of various Web-based services, design of high performance, scalable and dependable data centers has become a critical issue. Recent studies show that a clustered, multi-tier architecture is a cost-effective approach to design such servers. Since these servers are highly distributed and complex, understanding the work-loads driving them is crucial for the success of the ongoing research to improve them. In view of this, there has been a significant amount of work to characterize the workloads of Web-based services. However, all of the previous stud-ies focus on a high level view of these servers, and analyze request-based or session-based characteristics of the work-loads. In this paper, we focus on the characteristics of the network behavior within a clustered, multi-tiered data cen-ter. Using a real implementation of a clustered three-tier data center, we analyze the arrival rate and inter-arrival time distribution of the requests to individual server nodes, the network traffic between tiers, and the average size of messages exchanged between tiers. The main results of this study are; (1) in most cases, the request inter-arrival rates follow log-normal distribution, and self-similarity ex-ists when the data center is heavily loaded, (2) message sizes can be modeled by the log-normal distribution, and (3) service times fit reasonably well with the Pareto distri-bution and show heavy tailed behavior at heavy loads. 1.
Characteristics of streaming media stored on the Web
- ACM Transactions on Internet Technology (TOIT
, 2005
"... Despite the growth in multimedia, there have been few studies that focus on characterizing streaming audio and video stored on the Web. This investigation used a customized Web crawler to traverse 17 million Web pages from diverse geographic locations and identify nearly 30,000 streaming audio and v ..."
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Cited by 27 (3 self)
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Despite the growth in multimedia, there have been few studies that focus on characterizing streaming audio and video stored on the Web. This investigation used a customized Web crawler to traverse 17 million Web pages from diverse geographic locations and identify nearly 30,000 streaming audio and video clips available for analysis. Using custom-built extraction tools, these streaming media objects were analyzed to determine attributes such as media type, encoding format, playout duration, bitrate, resolution, and codec. The streaming media content encountered is dominated by proprietary audio and video formats with the top four commercial products being RealPlayer, Windows Media Player, MP3 and QuickTime. The distribution of the stored playout durations of streaming audio and video clips are long-tailed. More than half of the streaming media clips encountered are video, encoded primarily for broadband connections and at resolutions considerably smaller than the resolutions of typical monitors.
Variable Heavy Tailed Durations in Internet Traffic
"... This paper studies tails of the duration distribution of internet data flows, and their "heaviness". Data analysis ..."
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Cited by 24 (6 self)
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This paper studies tails of the duration distribution of internet data flows, and their "heaviness". Data analysis
A pragmatic approach to dealing with high-variability in network measurements
- In Proceedings of the 2nd ACM/Usenix Internet Measurement Conference (IMC’04
, 2004
"... The Internet is teeming with high variability phenomena, from mea-sured IP flow sizes to aspects of inferred router-level connectivity, but there still exists considerable debate about how best to deal with this encountered high variability and model it. While one popular approach favors modeling hi ..."
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Cited by 23 (7 self)
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The Internet is teeming with high variability phenomena, from mea-sured IP flow sizes to aspects of inferred router-level connectivity, but there still exists considerable debate about how best to deal with this encountered high variability and model it. While one popular approach favors modeling highly variable event sizes with conven-tional, finite variance distributions such as lognormal or Weibull distributions, Mandelbrot has argued for the last 40 years that there are compelling mathematical, statistical, and practical reasons for why infinite variance distributions are natural candidates for captur-ing the essence behind high variability phenomena. In this paper, we elaborate on Mandelbrot’s arguments and present a methodol-ogy that often allows for a clear distinction between the two ap-proaches. In particular, by requiring the resulting models to be resilient to ambiguities (i.e., robust to real-world deficiencies in the underlying network measurements) and internally self-consistent (i.e., insensitive with respect the duration, location, or time of the data collection), we provide a rigorous framework for a qualitative assessment of the observed high variability. We apply the proposed framework to assess previously reported findings about measured Internet traffic and inferred router- and AS-level connectivity. In the process, we also discuss what our approach has to say about re-cent discussions concerning network traffic being Poisson or self-similar and router-level or AS-level connectivity graphs of the In-ternet being scale-free or not.
Preventing large sojourn times using SMART scheduling
- Operations Research
, 2005
"... Recently, the class of SMART scheduling policies has been introduced in order to formalize the common heuristic of “biasing toward small jobs. ” We study the tail of the sojourn-time (response-time) distribution under both SMART policies and the Foreground-Background policy (FB) in the GI/GI/1 queue ..."
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Cited by 16 (8 self)
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Recently, the class of SMART scheduling policies has been introduced in order to formalize the common heuristic of “biasing toward small jobs. ” We study the tail of the sojourn-time (response-time) distribution under both SMART policies and the Foreground-Background policy (FB) in the GI/GI/1 queue. We prove that these policies behave very well under heavy-tailed service times. Specifically, we show that the sojourn-time tail under all SMART policies and FB is similar to that of the service-time tail, up to a constant, which makes the SMART class superior to First-Come-First-Served (FCFS). In contrast, for light-tailed service times, we prove that the sojourn-time tail under FB and SMART is larger than that under FCFS. However, we show that the sojourn-time tail for a job of size y under FB and all SMART policies still outperforms FCFS as long as y is not too large.
Measuring large overlay networks - the overnet example
- In Proceedings of the 14th KiVS
, 2005
"... Abstract Peer-to-peer overlay networks have grown significantly in size and sophistication over the last years. Meanwhile, distributed hash tables (DHT) provide efficient means to create global scale overlay networks on top of which various applications can be built. Although filesharing still is th ..."
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Cited by 15 (0 self)
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Abstract Peer-to-peer overlay networks have grown significantly in size and sophistication over the last years. Meanwhile, distributed hash tables (DHT) provide efficient means to create global scale overlay networks on top of which various applications can be built. Although filesharing still is the most prominent example, other applications are well conceivable. In order to rationally design such applications, it is important to know (and understand) the properties of the overlay networks as seen from the respective application. This paper reports the results from a two week measurement of the entire Overnet network, the currently most widely deployed DHT-based overlay. We describe both, the design choices that made that measurement feasible and the results from the measurement itself. Besides the basic determination of network size, node availability and node distribution, we found unexpected results for the overlay latency distribution. 1 Description of Overnet and Kademlia
Generation and Validation of Empirically-Derived TCP Application Workloads
, 2006
"... This dissertation proposes and evaluates a new approach for generating realistic traffic in networking experiments. The main problem solved by our approach is generating closed-loop traffic consistent with the behavior of the entire set of applications in modern traffic mixes. Unlike earlier appro ..."
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Cited by 11 (0 self)
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This dissertation proposes and evaluates a new approach for generating realistic traffic in networking experiments. The main problem solved by our approach is generating closed-loop traffic consistent with the behavior of the entire set of applications in modern traffic mixes. Unlike earlier approaches, which described individual applications in terms of the specific semantics of each application, we describe the source behavior driving each connection in a generic manner using the a-b-t model. This model provides an intuitive but detailed way of describing source behavior in terms of connection vectors that capture the sizes and ordering of application data units, the quiet times between them, and whether data exchange is sequential or concurrent. This is consistent with the view of traffic from TCP, which does not concern itself with application semantics. The a-b-t model also satisfies a crucial property: given a packet header trace collected from an arbitrary Internet link, we can algorithmically infer the source-level behavior driving each connection,
Blocking time analysis of obs routers with arbitrary burst size distribution
- In Proceedings of GLOBECOM
, 2003
"... Abstract — The blocking time distribution for an OBS router is obtained, under the assumption of Poisson-arriving bursts with Pareto, Gaussian and Exponential burst size distributions. Analytical expressions are provided as a function of number of wavelengths per port. Such expressions can be used t ..."
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Cited by 10 (4 self)
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Abstract — The blocking time distribution for an OBS router is obtained, under the assumption of Poisson-arriving bursts with Pareto, Gaussian and Exponential burst size distributions. Analytical expressions are provided as a function of number of wavelengths per port. Such expressions can be used to dimension Fiber Delay Lines (FDLs) and to perform end-to-end delay estimation. On the other hand, we show that the blocking time distribution becomes exponential as the number of wavelengths increases, regardless of the burst size distribution. Since the burst size distribution is determined by the burst assembly algorithm at the network edges, we conclude that the burst assembly algorithm will have no influence on both burst blocking probability and burst blocking time in future DWDM networks.
