Showing papers on "Network traffic simulation published in 2000"

NetScope: traffic engineering for IP networks

Abstract: Managing large IP networks requires an understanding of the current traffic flows, routing policies, and network configuration. However, the state of the art for managing IP networks involves manual configuration of each IP router, and traffic engineering based on limited measurements. The networking industry is sorely lacking in software systems that a large Internet service provider can use to support traffic measurement and network modeling, the underpinnings of effective traffic engineering. This article describes the AT&T Labs NetScope, a unified set of software tools for managing the performance of IP backbone networks. The key idea behind NetScope is to generate global views of the network on the basis of configuration and usage data associated with the individual network elements. Having created an appropriate global view, we are able to infer and visualize the networkwide implications of local changes in traffic, configuration, and control. Using NetScope, a network provider can experiment with changes in network configuration in a simulated environment rather than the operational network. In addition, the tool provides a sound framework for additional modules for network optimization and performance debugging. We demonstrate the capabilities of the tool through an example traffic engineering exercise of locating a heavily loaded link, identifying which traffic demands flow on the link, and changing the configuration of intradomain routing to reduce the congestion.

A predictability analysis of network traffic

Abstract: This paper assesses the predictability of network traffic by considering two metrics: (1) how far into the future a traffic rate process can be predicted for a given error constraint; (2) what the minimum prediction error is over a specified prediction time interval. The assessment is based on two stationary traffic models: the auto-regressive moving average (ARMA) model and the Markov-modulated Poisson process (MMPP) model. Our study in this paper provides an upper bound for the optimal performance of online traffic prediction. The analysis reveals that the application of traffic prediction is limited by the quickly deteriorating prediction accuracy with increasing prediction interval. Furthermore, we show that different traffic properties play different roles in predictability. Traffic smoothing (low-pass filtering) and statistical multiplexing also improves predictability. In particular, experimental results suggest that traffic prediction works better for backbone network traffic, or when short-term traffic variations have been properly filtered out. Moreover, this paper illustrates the various factors affecting the effectiveness of traffic prediction in network control. These factors include the traffic characteristics, the traffic measurement intervals, the network control time-scale, and the utilization target of network resources. Considering all of the factors, we present guidelines for utilizing and evaluating traffic prediction in network control areas.

Methods and apparatus for network use optimization

Abstract: A method and apparatus for assessing network traffic loads, separating the network traffic into the traffic classes either with or without specific client priority/business input, and managing the allocation of available network resources based on the class of the traffic. Differentiated traffic classes of communication services, such as time sensitive and non-time sensitive, may be specified via a set of parameters to permit a network to provide corresponding services that result in a guaranteed amount of available network resources, such as bandwidth. The set of parameters allows the network operator to categorize each type of network traffic into traffic classes and designate a predetermined level of network resources per class, thereby achieving the QoS—Quality of Service—and predictable traffic service performance guarantee appropriate to the needs of the end users of the network in a multi-class, multi-priority network environment.

System for traffic data evaluation of real network with dynamic routing utilizing virtual network modelling

Abstract: To provide an improved approach to traffic data evaluation in a network using dynamic routing there is provided a traffic data evaluation apparatus for a network using dynamic routing comprising traffic data collection means (12) to collect data with respect to a real traffic flow in the network. Further, the traffic data evaluation apparatus comprises a network modelling unit (14, 16) to model the network through a virtual network having virtual links without capacity restrictions imposed thereon. Still further, there is provided a network load evaluation means (18) to map the real traffic flow onto the virtual network assuming optimal routing and to compare the capacity used for each virtual link with the capacity assigned thereto. Thus, it is possible to draw conclusions on the network load by real network measurements also for a network using a dynamic routing protocol.

Methods and apparatus for characterization, adjustment and optimization of wireless networks

Abstract: Improved techniques for characterizing, adjusting and optimizing the overall performance of a wireless network. In an illustrative embodiment, the overall network performance for a particular network configuration is characterized by a vector with two components, one representing network coverage and another representing network capacity. Network coverage is defined by the likelihood of service under load, including interference, and may be further weighted by traffic density. Network capacity is defined by an amount of traffic with a given spatial distribution that can be served at a given overall target-blocking rate. The overall network performance may be characterized using a two-dimensional capacity/coverage diagram which plots overall network performance vectors, each including a network capacity component and a network coverage component, for various network configurations. The overall network performance may be improved or optimized with respect to a given subset of network parameters by using an algorithm that proposes potential network configurations and evaluates them with respect to their overall network performance.

Time-stepped hybrid simulation (TSHS) for large scale networks

Abstract: Data communication networks have been experiencing tremendous growth in size, complexity, and heterogeneity over the last decade. This trend poses a significant challenge to the design of scalable performance evaluation methodologies. In this paper we propose time-stepped hybrid simulation (TSHS) to deal with the scalability issue faced by traditional packet-level discrete event simulation methods. TSHS is a framework that offers the user the flexibility to choose the simulation time scale so as to trade off the computational cost of the simulation with its fidelity. Simulation speedup is achieved by evaluating the system at coarser time-scales. The potential loss of simulation accuracy when fine-time-scale behavior is evaluated at a coarser time-scale is studied both analytically and experimentally.

Automated and adaptive management of bandwidth capacity in telecommunications networks

Abstract: Management of the bandwidth capacity of tunnels through a network may be automated such that the network is adaptive to the stochastic nature of incoming traffic An edge node in the network includes four main elements Three of the elements, namely tunnel signaling, admission control and path selection, are derived from known technologies, generalized from their particular technologies and enhanced With the addition of a fourth element, called capacity management, the four elements cooperate to accommodate the capacity needs of the traffic incoming to the network at the edge node This accommodation is performed by estimating the traffic demand and dynamically adapting tunnels to the traffic demand

Parallel computer network and method for telecommunications network simulation to route calls and continuously estimate call billing in real time

Abstract: A telecommunications call routing and billing computer system includes a telecommunications network including a junction point including a call routing switching device, and including two call routing links meeting at the junction point and in communication with each other through the call routing switching device; and a call routing simulation network including a junction point simulation computer located at the junction point and in communication with the call routing switching device and the two call routing links. A method of placing a call through such a telecommunications network includes the steps of: placing one junction point simulation computer at each telecommunications network call junction point; for each call placed with the telecommunications network, plotting a call routing vector through the simulation network with forward chaining through the junction point simulation computers; and sending routing vector information back through the simulation network with rearward chaining to direct the call along a parallel routing vector through the telecommunications network. The method preferably includes the additional steps of: monitoring buffer levels of telecommunications network junction point computers with the simulation computer at each junction point; and using the buffer level information to shunt calls from telecommunications network junction point computers having smaller buffers to those having larger buffers.

Application of agent technology to traffic simulation

Abstract: The economic impact of traffic management grows each day. Infrastructure improvements are costly, hence any such project must be carefully evaluated for its impact on the traffic. Emphasis on traffic simulation tools has increased in the last five years to help evaluate new traffic-control strategies, as well as planned road constructions. Building high-quality traffic simulations has several challenges, including computational performance, the accuracy of models in representing the traffic flow, and the difficulty of integration with advanced traffic management and traffic information systems. In this paper, the authors report on work on an agent-based approach to traffic simulation, and how it addresses these issues.

Network Management and control using collaborative on-line simulation

Abstract: A collaborative on-line simulation system and method to provide automated and pro-active control functions for computer network. In a wide area network, clients communicate through one or several nodes (108). Each node (108) contains routers which include control plane (202) and data plane (204). Collaborative on-line simulators (206) are interfaced to the network nodes (108) and continuously monitor the surrounding network conditions, communicate with other simulators and execute collaborative on-line simulation. Based on the simulation results, the on-line simulators (206) continuously tune selected network parameters to a more efficient operation point to fit the current network conditions.

Internet Traffic Data

Abstract: (2000). Internet Traffic Data. Journal of the American Statistical Association: Vol. 95, No. 451, pp. 979-985.

Metropolitan network traffic demand study

Abstract: A comprehensive metropolitan network traffic demand model has been developed and used to determine the network characteristics of a large metropolitan area. Network connectivity based on traffic demand analysis has been determined from which node and ring characteristics were gathered. The distributions of connection capacity as a function of connection length and traffic by application were also presented. These data can be used to determine future requirements of fiber and equipment used in a large metropolitan network.

Analysis of network traffic and its application to design of high-speed routers

Abstract: SUMMARY A rapid growth of the Internet and proliferation of new multimedia applications lead to demands of high speed and broadband network technologies. Routers are also necessary to follow up the growth of link bandwidths. From this reason, there have been many researches on high speed routers having switching capabilities. To have an expected effect, however, a control parameters set based on traffic characteristics are necessary. In this paper, we analyze the network traffic using the network traffic monitor and investigate the Internet traffic characteristics through a statistical analysis. We next show the application of our analytical results to parameter settings of high speed switching routers. Simulation results show that our approach makes highly utilized VC space and high performance in packet processing delay. We also show the effect of flow aggregation on MPLS. From our results, the flow aggregation has a great impact on the

Providing quality of service in the internet

Abstract: This dissertation presents a framework for providing quality of service (QoS) in the Internet. This framework consists of traffic directing and load balancing at the application layer, differentiated services (Diffserv) at the transport layer, traffic engineering and fast reroute at the network layer. Traffic directing is to utilize the high-performance part of a network as much as possible and avoid using the low performance part. Load balancing is to distribute client requests to multiple servers so that service availability and responsiveness is increased. Approaches for traffic directing and load balancing are briefly described. Diffserv is to divide traffic into different classes and treat them differently, especially when there is a shortage of network resources. Mechanisms needed at the edge and at the core of the network are described. These mechanisms can be used to achieve the desired per-hop behaviors (PHBs). By concatenating all these PHBs together, a certain level of QoS can be provided end to end. A conflict between Diffserv and TCP is also described, and a solution for resolving this conflict is proposed. This solves a significant problem in the Internet. Traffic engineering is an iterative process of network planning and network optimization. Network planning is to improve the architecture (topology and link capacity) of a network in a systematic way so that the network is easy to operate, robust, and adaptive. Network optimization is to control the mapping and distribution of traffic over the existing network infrastructure to avoid and/or relieve congestion, and thus to optimize resource efficiency. The issues of designing a traffic engineering systems are discussed. A national traffic engineering system with multi-protocol label switching (MPLS) is then presented, and its performance evaluated. Based on the experience of implementing this system, a generic procedure is proposed for deploying large-scale traffic engineering systems. An approach for performing inter-domain traffic engineering in a quantitative way is then described. We also propose an offline constraint-based routing algorithm for computing the paths for MPLS label switched paths (LSPs), and describe how to provide Diffserv in an MPLS environment. Two emerging technologies that are closely related to traffic engineering, multi-protocol lambda switching (MPLmS) and fast reroute , are also discussed. Constraint-based routing is one of the most important tools for traffic engineering. The issues related to constraint-based routing are discussed in detail. Heuristics for computing paths with propagation delay constraint, and for QoS routing on the top of virtual networks constructed in the traffic engineering process, are proposed. In order to reduce the computation complexity of constraint-based routing, an algorithm is proposed for reducing the routing table computation cost for OSPF. The correctness of the algorithm is illustrated. Similar idea can also be applied to IS-IS. In summary, this dissertation not only discusses on all major issues related to QoS, but also presents a systematic approach for providing QoS in the Internet.

Comparing local search with respect to genetic evolution to detect intrusions in computer networks

Abstract: The detection of intrusions over computer networks (i.e., network access by non-authorized users) can be cast to the task of detecting anomalous patterns of network traffic. In this case, models of normal traffic have to be determined and compared against the current network traffic. Data mining systems based on genetic algorithms can contribute powerful search techniques for the acquisition of patterns of the network traffic from the large amount of data made available by audit tools. We compare models of network traffic acquired by a system based on a distributed genetic algorithm with the ones acquired by a system based on greedy heuristics. Also we provide an empirical proof that representation change of the network data can result in a significant increase in the classification performances of the traffic models. Network data made available from the Information Exploration Shootout project and the 1998 DARPA Intrusion Detection Evaluation have been chosen as experimental testbed.

Simulation of distribution systems: simulation and analysis of non-automated distribution warehouses

Abstract: The distribution warehouse is located between manufacturers and customers Storage facilities are designed around four primary functions: holding, consolidation, break-bulk, and mixing In addition, materials handling within a storage-handling system reduces to three primary activities: loading and unloading, movement to and from storage, and order filling Generally, it is more difficult to build a simulation model for a non-automated warehouse than for AS/RS, because materials handling is much more complicated In this study, a procedure to build simulation models for move-store activities of complicated and non-automated distribution warehouses is proposed The simulation model here is designed to execute together with the program for generating parameters of materials handling Then, simulation analysis is performed, using a simulation model built by the proposed procedure

On the burstiness of the TCP congestion-control mechanism in a distributed computing system

Abstract: Several studies in network traffic characterization have concluded that network traffic is self-similar and therefore not readily amenable to statistical multiplexing in a distributed computing system. This paper examines the effects of the TCP protocol stack on network traffic via an experimental study on the different implementations of TCP. We show that even when aggregate application traffic smooths out as more applications' traffic are multiplexed, TCP introduces burstiness into the aggregate traffic load, reducing network performance when statistical multiplexing is used within the network gateways.

Winner-take-all discrete recurrent neural networks

Abstract: This paper proposes a discrete recurrent neural network has simple organizations and clear dynamic behaviors. The dynamic properties of the proposed winner-take-all networks are studied detail. Simulation results are given to show network performance. Since the network model is formulated as discrete time systems, it has advantages for computer simulations over digital simulations of a continuous time neural network model. Thus they can be easily implemented in digital hardware.

Back-tracing and event-driven techniques in high-level simulation with decision diagrams

Abstract: The paper addresses the problem of the cycle-based simulation performance of synchronous digital systems modeled by High-Level Decision Diagrams (DDs). A new class of DD representation, called Register-Oriented DDs (RODD) is introduced. The RODD model appears to be an efficient and compact representation of the system behavior for the high-level cycle simulation. In order to fully exploit the advantages of RODDs a new simulation algorithm, which is a combination of cycle-based forward event-driven and recursive back-tracing techniques is proposed. The characteristics of the simulation algorithms used to efficiently execute the evaluation of the DD network are discussed. Further the experimental results carried out on the real case examples demonstrating the gain in simulation performance of the proposed approach and a comparison of four cycle-based simulation algorithms are presented. Additionally, a comparison with the commercial event-driven and cycle-based HDL simulation tools is included.

Hardware-in-the-loop evaluation of traffic signal systems

Abstract: Vendors of modern traffic control equipment implement many unique algorithms designed to move traffic more efficiently. However, because of either the difficulty in modeling or the proprietary nature of the algorithms, many of these vendor specific algorithms can not be adequately evaluated using general purpose macroscopic or microscopic simulation models. This paper describes a procedure for incorporating actual traffic signal control equipment into a microscopic simulation to provide a rigorous of algorithms embedded in traffic devices. This procedure can be used to evaluate systems as diverse as SCOOT, SCATS or closed loop traffic responsive systems.

Distributed Event-driven Simulation - Scheduling Strategies and Resource Management

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Remote Simulation to Evaluate Real-Time Traffic Control Strategies

Abstract: Simulation is a valuable tool for evaluating the effects of various changes in a transportation system. This is especially true in the case of real-time traffic-adaptive control systems, which must undergo extensive testing in a laboratory setting before being implemented in a field environment. Various types of simulation environments are available, from software-only to hardware-in-the-loop simulations, each of which has a role to play in the implementation of a traffic control system. The RHODES (real-time hierarchical optimized distributed effective system) real-time traffic-adaptive control system was followed as it progressed from a laboratory project toward actual field implementation. The traditional software-only simulation environment and extensions to a hardware-in-the-loop simulation are presented in describing the migration of RHODES onto the traffic controller hardware itself. In addition, a new enhancement to the standard software-only simulation that allows remote access is described. The enhancement removes the requirement that both the simulation and the traffic control scheme reside locally. This architecture is capable of supporting any traffic simulation package that satisfies specific input-output data requirements. This remote simulation environment was tested with several different types of networks and was found to perform in the same manner as its local counterpart. Remote simulation has all of the advantages of its local counterpart, such as control and flexibility, with the added benefit of distribution. This remote environment could be used in many different ways and by different groups or individuals, including state or local transportation agencies interested in performing their own evaluations of alternative traffic control systems.

Mining TCP/IP Traffic for Network Intrusion Detection by Using a Distributed Genetic Algorithm

Abstract: The detection of intrusions over computer networks (i.e., network access by non-authorized users) can be cast to the task of detecting anomalous patterns of network traffic. In this case, models of normal traffic have to be determined and compared against the current network traffic. Data mining systems based on Genetic Algorithms can contribute powerful search techniques for the acquisition of patterns of the network traffic from the large amount of data made available by audit tools. We compare models of network traffic acquired by a system based on a distributed genetic algorithm with the ones acquired by a system based on greedy heuristics. Also we discuss representation change of the network data and its impact over the performances of the traffic models. Network data made available from the Information Exploration Shootout project and the 1998 DARPA Intrusion Detection Evaluation have been chosen as experimental testbed.

Simulation based traffic information system

Abstract: There is a growing need for improvement in the efficiency of urban traffic in order to ensure the sustainability of modern cities. It is now recognized that this can be achieved through the coordinated improvement of traffic monitoring and management schemes in traffic control centers and the provision of information services for ordinary road users. The real-time (on-line) simulation can have an important role in these schemes. In this paper the concept of microscopic on-line traffic simulation is presented together with potential applications. As an application real-time traffic information service through Internet is presented. Also the use of on-line simulation for traffic control purposes is discussed. A prototype system is demonstrated based on HUTSIM urban traffic simulator, DIME distributed memory server and SCOOT- urban traffic control system. The presented methodology can be applied to other UTC-systems if proper real-time data is available. For the covering abstract see ITRD E114174.

Parallel execution of a sequential network simulator

Abstract: Parallel discrete event simulation (PDES) techniques have not yet made a substantial impact on the network simulation community because of the need to recast the simulation models using a new set of tools. To address this problem, we present a case study in transparently parallelizing a widely used network simulator, called ns. The use of this parallel ns does not require the modeler to learn any new tools or complex PDES techniques. The paper describes our approach and design choices to build the parallel ns and presents preliminary performance results, which are very encouraging.

A system, method and article of manufacture for network performance modeling

Abstract: A system, method and article of manufacture are provided for network performance modeling Factors that influence a performance of a network are first identified Next, a model is developed to simulate the performance of the network based on the identified factors Operation of the network is then simulated with the model with the simulation being carried out using expected future loads The network is then designed based on results of the simulation in order to accommodate the expected future loads on the network

An evaluation of traffic simulation models for supporting intelligent transportation systems (its) development

Abstract: Tools to evaluate networks under information supply are a vital necessity in light of the systems being implemented as part of the Intelligent Transportation Systems (ITS) deployment plan. One such tool is the traffic simulation model. This report presents an evaluation of the existing traffic simulation models to identify the models that can be potentially applied in ITS equipped networks. The traffic simulation models are categorized according to type (macroscopic, microscopic or mesoscopic), as well as functionality (highway, signal, integrated). The entire evaluation is conducted through two steps: initial screening and in-depth evaluation. The initial step generates a shorter but more specific list of traffic simulation models based on some pre-determined criteria. The in-depth evaluation identifies which model on the shorter list is suitable for a specific area of ITS applications. It is concluded from this research that presently CORSIM and INTEGRATION appear to have the highest probability of success in real-world applications. It is also found that by adding more calibration and validation in the U.S., the AIMSUN 2 and PARAMICS models will be brought to the forefront in the near term for use with ITS applications.