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185
Why We Don't Know How to Simulate the Internet
, 1997
"... Simulating how the global Internet data network behaves is an immensely challenging undertaking because of the network's great heterogeneity and rapid change. The heterogeneity ranges from the individual links that carry the network's traffic, to the protocols that interoperate over the li ..."
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Cited by 230 (4 self)
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Simulating how the global Internet data network behaves is an immensely challenging undertaking because of the network's great heterogeneity and rapid change. The heterogeneity ranges from the individual links that carry the network's traffic, to the protocols that interoperate over the links, to the "mix" of different applications used at a site and the levels of congestion (load) seen on different links. We discuss two key strategies for developing meaningful simulations in the face of these difficulties: searching for invariants and judiciously exploring the simulation parameter space. We finish with a look at a collaborative effort to build a common simulation environment for conducting Internet studies.
Data networks as cascades: Investigating the multifractal nature of Internet WAN traffic
, 1998
"... In apparent contrast to the well-documented self-similar (i.e., monofractal) scaling behavior of measured LAN traffic, recent studies have suggested that measured TCP/IP and ATM WAN traffic exhibits more complex scaling behavior, consistent with multifractals. To bring multifractals into the realm o ..."
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Cited by 221 (14 self)
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In apparent contrast to the well-documented self-similar (i.e., monofractal) scaling behavior of measured LAN traffic, recent studies have suggested that measured TCP/IP and ATM WAN traffic exhibits more complex scaling behavior, consistent with multifractals. To bring multifractals into the realm of networking, this paper provides a simple construction based on cascades (also known as multiplicative processes) that is motivated by the protocol hierarchy of IP data networks. The cascade framework allows for a plausible physical explanation of the observed multifractal scaling behavior of data traffic and suggests that the underlying multiplicative structure is a traffic invariant for WAN traffic that co-exists with self-similarity. In particular, cascades allow us to refine the previously observed self-similar nature of data traffic to account for local irregularities in WAN traffic that are typically associated with networking mechanisms operating on small time scales, such as TCP flo...
On the Effect of Traffic Self-similarity on Network Performance
, 1997
"... Recent measurements of network traffic have shown that self-similarity is an ubiquitous phenomenon present in both local area and wide area traffic traces. In previous work, we have shown a simple, robust application layer causal mechanism of traffic self-similarity, namely, the transfer of files i ..."
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Cited by 121 (10 self)
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Recent measurements of network traffic have shown that self-similarity is an ubiquitous phenomenon present in both local area and wide area traffic traces. In previous work, we have shown a simple, robust application layer causal mechanism of traffic self-similarity, namely, the transfer of files in a network system where the file size distributions are heavy-tailed. In this paper, we study the effect of scale-invariant burstiness on network performance when the functionality of the transport layer and the nteraction of traffic sources sharing bounded network resources is incorporated. First, we show that transport layer mechanisms are important factors in translating the application layer causality into link traffic self-similarity. Network performance as captured by throughput, packet loss rate, and packet retransmission rate degrades gradually with increased heavy-tailedness while queueing delay, response time, and fairness deteriorate more drastically. The degree to which heavy-tailedness affects self-similarity is determined by how well congestion control is able to shape a source traffic into an on-average constant output stream while conserving information. Second, we show that increasing network resources such as link bandwidth and buffer capacity results in a superlinear improvement in performance. When large file transfers occur with nonnegligible probability, the incremental
Source Models of Network Game Traffic
- Computer Communications
, 2000
"... We study the traffic generated by sessions of a popular multi-player network game. Our analysis indicates that empirical game traffic can be characterized well by certain analytical models. While clients and servers, as well as hosts with different configurations, produce different models, all model ..."
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Cited by 93 (0 self)
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We study the traffic generated by sessions of a popular multi-player network game. Our analysis indicates that empirical game traffic can be characterized well by certain analytical models. While clients and servers, as well as hosts with different configurations, produce different models, all models from the game are well modeled by the same families of distributions. We find that some data sets are best modeled with split distributions; that is, one portion of the data is well-modeled with one particular distribution, and the rest of the data with another. We describe how our models can be simulated and discuss how host processing speed influences packet interarrival distributions. As Internet gaming becomes more popular, we expect that our models will be useful for testing hardware and protocols that support gaming. 2 ______________________________________________________________________________________ Borella, Source Models of Network Game Traffic 1 Introduction Interactive,...
Small-Time Scaling Behaviors of Internet Backbone Traffic: An Empirical Study
- In Proceedings of the IEEE Infocom
, 2003
"... Abstract — We study the small-time (sub-seconds) scaling behaviors of Internet backbone traffic, based on traces collected from OC3/12/48 links in a tier-1 ISP. We observe that for a majority of these traces, the (second-order) scaling exponents at small time scales (1ms- 100ms) are fairly close to ..."
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Cited by 78 (7 self)
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Abstract — We study the small-time (sub-seconds) scaling behaviors of Internet backbone traffic, based on traces collected from OC3/12/48 links in a tier-1 ISP. We observe that for a majority of these traces, the (second-order) scaling exponents at small time scales (1ms- 100ms) are fairly close to 0.5, indicating that traffic fluctuations at these time scales are (nearly) uncorrelated. In addition, the traces manifest mostly monofractal behaviors at small time scales. The objective of the paper is to understand the potential causes or factors that influence the smalltime scalings of Internet backbone traffic via empirical data analysis. We analyze the traffic composition of the traces along two dimensions – flow size and flow density. Our study uncovers dense flows (i.e., flows with bursts of densely clustered packets) as the correlation-causing factor in small time scales, and reveals that the traffic composition in terms of proportions of dense vs. sparse flows plays a major role in influencing the small-time scalings of aggregate traffic. I.
Provisioning servers in the application tier for e-commerce systems
- In Proceedings of the Twelfth IWQoS
, 2004
"... Server providers that support e-commerce applications as a service for multiple e-commerce Web sites traditionally use a tiered server architecture. This architecture includes an application tier to process requests for dynamically generated content. How this tier is provisioned can significantly im ..."
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Cited by 63 (0 self)
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Server providers that support e-commerce applications as a service for multiple e-commerce Web sites traditionally use a tiered server architecture. This architecture includes an application tier to process requests for dynamically generated content. How this tier is provisioned can significantly impact a provider’s profit margin. In this article we study methods to provision servers in the application serving tier that increase a server provider’s profits. First, we examine actual traces of request arrivals to the application tier of an e-commerce site, and show that the arrival process is effectively Poisson. Next, we construct an optimization problem in the context of a set of application servers modeled as M/G/1/PS queueing systems, and derive three simple methods that approximate the allocation that maximizes profits. Simulation results demonstrate that our approximation methods achieve profits that are close to optimal, and are significantly higher than those achieved via simple heuristics.
Simple Performance Models of Differentiated Services Schemes for the Internet
, 1999
"... Schemes based on the tagging of packets have recently been proposed as a low-cost way to augment the single class best effort service model of the current Internet by including some kind of service discrimination. Such schemes have a number of attractive features, however, it is not clear exactly wh ..."
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Cited by 63 (0 self)
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Schemes based on the tagging of packets have recently been proposed as a low-cost way to augment the single class best effort service model of the current Internet by including some kind of service discrimination. Such schemes have a number of attractive features, however, it is not clear exactly what kind of service they would provide to applications. Yet quantifying such service is very important to understand the benets and drawbacks of the different tagging schemes and of the mechanisms in each scheme (for example how much RIO contributes in the Assured scheme), and to tackle key performance and economic issues (e.g. the difference in tariff between different service classes would presumably depend on the difference in performance between the classes). Our goal in this paper is to obtain a quantitative description of the service provided by tagging schemes. Specically, we describe and solve simple analytic models of two recently proposed schemes, namely the Assured Service scheme ...
On the influence of self similarity on Optical Burst Switching traffic
- In IEEE Globecom
, 2002
"... Abstract — In this paper we provide a characterization of OBS traffic (burst size, interarrival time and scaling behavior) when the input traffic is long-range dependent. The analysis shows that the influence of selfsimilarity on blocking probability is negligible, since the arrival process can be a ..."
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Cited by 50 (11 self)
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Abstract — In this paper we provide a characterization of OBS traffic (burst size, interarrival time and scaling behavior) when the input traffic is long-range dependent. The analysis shows that the influence of selfsimilarity on blocking probability is negligible, since the arrival process can be assumed to be Poisson in the timescale of interest for burst blocking. However, the impact for optical buffer dimensioning is significant. On the other hand, the scaling region is shifted to larger timescales while traffic variability at low timescales is increased. These findings serve to accurately dimension number of output ports and optical buffers in OBS routers when the incoming traffic comes from a large population of Internet users.
On the autocorrelation structure of TCP traffic
, 2000
"... The statistical characteristics of network traffic- in particular the observation that it can exhibit long range dependence- have received considerable attention from the research community over the past few years. In addition, the recent claims that the TCP protocol can generate traffic with long r ..."
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Cited by 48 (7 self)
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The statistical characteristics of network traffic- in particular the observation that it can exhibit long range dependence- have received considerable attention from the research community over the past few years. In addition, the recent claims that the TCP protocol can generate traffic with long rage dependent behavior has also received much attention. Contrary to the latter claims, in this paper we show that the TCP protocol can generate traffic with correlation structures that spans only an analytically predictable finite range of time-scales. We identify and analyze separately the two mechanisms within TCP that are responsible for this scaling be-havior: timeouts and congestion avoidance. We provide analytical models for both mechanisms that, under the proper loss probabilities, accurately predict the range in time-scales and the strength of the sustained correlation structure of the traffic sending rate of a single TCP source. We also analyze an existing comprehensive model of TCP that accounts for both mechanisms and show that TCP itself exhibits a predictable finite range of time-scales under which traffic presents sustained correlations. Our claims and results are derived from Markovian models that are supported by simulations. We note that traffic generated by TCP can be misinterpreted to have long range dependence, but that long range dependence is not possible due to inherent finite time-scales of the mechanisms of TCP.
C.: Why is the internet traffic bursty in short time scales
- In ACM SIGMETRICS
, 2005
"... Internet traffic exhibits multifaceted burstiness and correlation structure over a wide span of time scales. Previous work analyzed this structure in terms of heavy-tailed session characteristics, as well as TCP timeouts and congestion avoidance, in relatively long time scales. We focus on shorter s ..."
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Cited by 48 (1 self)
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Internet traffic exhibits multifaceted burstiness and correlation structure over a wide span of time scales. Previous work analyzed this structure in terms of heavy-tailed session characteristics, as well as TCP timeouts and congestion avoidance, in relatively long time scales. We focus on shorter scales, typically less than 100-1000 milliseconds. Our objective is to identify the actual mechanisms that are responsible for creating bursty traffic in those scales. We show that TCP self-clocking, joint with queueing in the network, can shape the packet interarrivals of a TCP connection in a two-level ON-OFF pattern. This structure creates strong correlations and burstiness in time scales that extend up to the Round-Trip Time (RTT) of the connection. This effect is more important for bulk transfers that have a large bandwidth-delay product relative to their window size. Also, the aggregation of many flows, without rescaling their packet interarrivals, does not converge to a Poisson stream, as one might expect from classical superposition results. Instead, the burstiness in those scales can be significantly reduced by TCP pacing. In particular, we focus on the importance of the minimum pacing timer, and show that a 10-millisecond timer would be too coarse for removing short-scale traffic burstiness, while a 1-millisecond timer would be sufficient to make the traffic almost as smooth as a Poisson stream in sub-RTT scales.
