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44
On the nonstationarity of Internet traffic
- IN PROCEEDINGS OF ACM SIGMETRICS 2001
, 2001
"... Traffic variables on an uncongested Internet wire exhibit a pervasive nonstationarity. As the rate of new TCP connections increases, arrival processes (packet and connection) tend locally toward Poisson, and time series variables (packet sizes, transferred file sizes, and connection round-trip times ..."
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Cited by 71 (5 self)
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Traffic variables on an uncongested Internet wire exhibit a pervasive nonstationarity. As the rate of new TCP connections increases, arrival processes (packet and connection) tend locally toward Poisson, and time series variables (packet sizes, transferred file sizes, and connection round-trip times) tend locally toward independent. The cause of the nonstationarity is superposition: the intermingling of sequences of connections between different source-destination pairs, and the intermingling of sequences of packets from different connections. We show this empirically by extensive study of packet traces for nine links coming from four packet header databases. We show it theoretically by invoking the mathematical theory of point processes and time series. If the connection rate on a link gets sufficiently high, the variables can be quite close to Poisson and independent; if major congestion occurs on the wire before the rate gets sufficiently high, then the progression toward Poisson and independent can be arrested for some variables.
Evaluating the Impact of Stale Link State on Quality-of-Service Routing
, 2001
"... Quality-of-service (QoS) routing satisfies application performance requirements and optimizes network resource usage by selecting paths based on connection traffic parameters and link load information. However, distributing link state imposes significant bandwidth and processing overhead on the net ..."
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Cited by 56 (0 self)
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Quality-of-service (QoS) routing satisfies application performance requirements and optimizes network resource usage by selecting paths based on connection traffic parameters and link load information. However, distributing link state imposes significant bandwidth and processing overhead on the network. This paper investigates the performance trade-off between protocol overhead and the quality of the routing decisions in the context of the source-directed, link-state routing protocols proposed for IP and ATM networks. We construct a detailed model of QoS routing that parameterizes the path-selection algorithm, link-cost function, and link-state update policy. Through extensive simulation experiments with several network topologies and traffic patterns, we uncover the effects of stale link-state information and random fluctuations in traffic load on the routing and set-up overheads. We then investigate how inaccuracy of linkstate information interacts with the size and connectivity of the underlying topology. Finally, we show that tuning the coarseness of the link-cost metric to the inaccuracy of underlying link-state information reduces the computational complexity of the path-selection algorithm without significantly degrading performance. This work confirms and extends earlier studies, and offers new insights for designing efficient quality-of-service routing policies in large networks.
Evidence for long-tailed distributions in the Internet
- In Proceedings of ACM SIGCOMM Internet Measurment Workshop
, 2001
"... We review evidence that Internet traffic is characterized by long-tailed distributions of interarrival times, transfer times, burst sizes and burst lengths. We propose a new statistical technique for identifying long-tailed distributions, and apply it to a variety of datasets collected on the Intern ..."
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Cited by 44 (0 self)
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We review evidence that Internet traffic is characterized by long-tailed distributions of interarrival times, transfer times, burst sizes and burst lengths. We propose a new statistical technique for identifying long-tailed distributions, and apply it to a variety of datasets collected on the Internet. We find that there is little evidence that interarrival times and transfer times are long-tailed, but that there is some evidence for long-tailed burst sizes. We speculate on the causes of long-tailed bursts. I.
Modeling Internet Backbone Traffic at the Flow Level
- IEEE Transactions on Signal processing
, 2003
"... Our goal is to design a traffic model for non congested Internet backbone links, which is simple enough to be used in network operation, while being as general as possible. The proposed solution is to model the traffic at the flow level by a Poisson shot-noise process. In our model, a flow is a gene ..."
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Cited by 37 (3 self)
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Our goal is to design a traffic model for non congested Internet backbone links, which is simple enough to be used in network operation, while being as general as possible. The proposed solution is to model the traffic at the flow level by a Poisson shot-noise process. In our model, a flow is a generic notion that must be able to capture the characteristics of any kind of data stream. We analyze the accuracy of the model with real traffic traces collected on the Sprint IP (Internet Protocol) backbone network. Despite its simplicity, our model provides a good approximation of the real traffic observed in the backbone and of its variation. Finally, we discuss the application of our model to network design and dimensioning.
Cluster Load Balancing for Fine-grain Network Services
- IN PROC. OF INTERNATIONAL PARALLEL & DISTRIBUTED PROCESSING SYMPOSIUM, FORT LAUDERDALE, FL
, 2002
"... This paper studies cluster load balancing policies and system support for fine-grain network services. Load balancing on a cluster of machines has been studied extensively in the literature, mainly focusing on coarse-grain distributed computation. Fine-grain services introduce additional challenges ..."
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Cited by 30 (7 self)
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This paper studies cluster load balancing policies and system support for fine-grain network services. Load balancing on a cluster of machines has been studied extensively in the literature, mainly focusing on coarse-grain distributed computation. Fine-grain services introduce additional challenges because system states fluctuate rapidly for those services and system performance is highly sensitive to various overhead. The main contribution of our work is to identify effective load balancing schemes for fine-grain services through simulations and empirical evaluations on synthetic workload and real traces. Another contribution is the design and implementation of a load balancing system in a Linux cluster that strikes a balance between acquiring enough load information and minimizing system overhead. Our study concludes that: 1) Random polling based loadbalancing policies are well-suited for fine-grain network services; 2) A small poll size provides sufficient information for load balancing, while an excessively large poll size may in fact degrade the performance due to polling overhead; 3) Discarding slow-responding polls can further improve system performance.
IP Packet Generation: Statistical Models for TCP Start Times Based on Connection-Rate Superposition
- Proc. ACM Sigmetrics 2000
, 2000
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A compound model for TCP connection arrivals
- LAN AND WAN APPLICATIONS. COMPUTER NETWORKS, 40(3):319 – 337
, 2000
"... We propose a two level model for TCP connection arrivals in local area networks. The first level are user sessions whose arrival is time-varying Poisson. The second level are connections within a user session. Their number and mean interarrival are independent and biPareto across user session. The i ..."
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Cited by 22 (0 self)
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We propose a two level model for TCP connection arrivals in local area networks. The first level are user sessions whose arrival is time-varying Poisson. The second level are connections within a user session. Their number and mean interarrival are independent and biPareto across user session. The interarrivals within a user session are Weibull, and across all users are correlated Weibull. Our model has a small number of parameters which are inferred from real traffic collected a a firewall. We show that traffic synthesized with our model closely characterizes the original data.
A compound model for TCP connection arrivals for LAN and WAN applications,
- Computer Networks: The International Journal of Computer and Telecommunications Networking,
, 2002
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Generating realistic TCP workloads
- In Computer Measurement Group International Conference
, 2004
"... The workload of a network is usually a heterogeneous aggregate of services and applications, driven by a large number of users. This complexity makes it challenging to evaluate the performance of network mechanisms and configurations under realistic conditions. We propose a new methodology for trans ..."
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Cited by 14 (2 self)
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The workload of a network is usually a heterogeneous aggregate of services and applications, driven by a large number of users. This complexity makes it challenging to evaluate the performance of network mechanisms and configurations under realistic conditions. We propose a new methodology for transforming anonymized traces of packet headers into application-neutral models of network traffic. These models are suitable for synthetic traffic generation in simulations and testbeds, preserving the end-to-end nature of network traffic. Our approach provides a tool for studying and tuning the realism of synthetic traffic.
