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Modeling, Analysis and Simulation of Computer and Telecommunication Systems, 1999. Proceedings. 7th International Symposium on

Date 24-28 Oct. 1999

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  • MASCOTS '99. Proceedings of the Seventh International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems

    Publication Year: 1999
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    Freely Available from IEEE
  • Table of contents

    Publication Year: 1999 , Page(s): v - viii
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    Freely Available from IEEE
  • The design and management of ATM virtual path connection networks

    Publication Year: 1999 , Page(s): 2 - 9
    Cited by:  Papers (1)  |  Patents (1)
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    Modern communication networks can cross connect traffic flows to form logical end-to-end connections between all origin-destination pairs and thus create fully meshed logical networks upon sparse physical networks. Such logical connections are known as virtual path connections (VPCs) and a logical network formed by VPCs is known as a VPC network (VPCN). We present an efficient algorithm called XFG to compute optimal configurations for VPCNs carrying multiservice traffic. We compare the features of the XFG algorithm and the characteristics of standard nonlinear programming solvers. We present a model where a sequence of busy period multiservice traffic is offered to a network. The XFG algorithm is used to compute an optimal VPCN design for each busy period. We compare the grade of service attained by VPCN redesign, dynamic alternative routing (DAR), and a combination of VPCN redesign, call queueing and DAR View full abstract»

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  • A synchronization protocol for group communication systems

    Publication Year: 1999 , Page(s): 322 - 329
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    With the evolution of network technologies, integrated services networks make possible real-time multimedia applications. However, the delay jitter and the absence of a physical global clock may disrupt the temporal relationships among media units composing theses multimedia applications. The Δ-causal ordering is designed to ensure real-time delivery of messages by respecting the causal order. This Δ value represents the limited lifetime during which a message m can be used by a destination process. In this paper, we develop a new real-time causal ordering concept, in the context of multicast communication, where all participants can start to playback the same message. We validate this model by using CPN (coloured Petri nets) tools to obtain a state space graph. The objective is to study the behavior of this model, by verifying different properties such as, boundedness, and liveness. The simulation result shows that this model respects the real-time causal ordering, in the context of multicast communications View full abstract»

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  • A generic framework for parallelization of network simulations

    Publication Year: 1999 , Page(s): 128 - 135
    Cited by:  Papers (24)
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    Discrete event simulation is widely used within the networking community for purposes such as demonstrating the validity of network protocols and architectures. Depending on the level of detail modeled within the simulation, the running time and memory requirements can be excessive. The goal of our research is to develop and demonstrate a practical, scalable approach to parallel and distributed simulation that will enable widespread reuse of sequential network simulation models and software. We focus on an approach to parallelization where an existing network simulator is used to build models of subnetworks that are composed to create simulations of larger networks. Changes to the original simulator care minimized, enabling the parallel simulator to easily track enhancements to the sequential version. We describe our lessons learned in applying this approach to the publicly available ns software package (McCanne and Floyd, 1997) and converting it to run in a parallel fashion on a network of workstations. This activity highlights a number of important problems, from the standpoint of how to parallelize an existing serial simulation model and achieving acceptable parallel performance View full abstract»

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  • Analysis of personal computer workloads

    Publication Year: 1999 , Page(s): 208 - 217
    Cited by:  Papers (5)  |  Patents (1)
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    Most published research on system behavior and workload characterization has been based on either Unix systems or large (usually IBM) mainframe systems. It is reasonable to believe that user behaviors and workloads are different for PC systems. Further, the aspects of system design and most-needed study have changed from the mainframes that were dominant in the 1960s and 1970s, and the Unix systems that became so popular in the 1980s, to the PCs that seem to be rapidly taking over many or most aspects of computing. Our analysis focuses instead on Microsoft Windows 95, which is currently the most widely used computer operating system; the newly released Windows 98 is very similar. In this paper, we describe a workload analysis based on 36 sets of traces collected from Intel Pentium-based PCs running the Windows 95 operating system. Following the discussion of our Windows 95 trace data, we present some descriptive and statistical characterizations of this data, directed principally at user behavior and file system behavior View full abstract»

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  • Local resource allocation for providing end to end delay guarantees in ATM networks using PGPS scheduling

    Publication Year: 1999 , Page(s): 30 - 37
    Cited by:  Papers (3)  |  Patents (1)
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    The paper addresses the issue of reserving resources at ATM switches along the path of flows that require a hard (deterministic) bound on end to end delay. The switches are assumed to be using packet-by-packet generalized processor sharing (PGPS) schedulers for each outgoing link. An algorithm for call admission control of these flows is proposed. Different policies for mapping the end to end delay requirement into service rates to be assigned at each scheduler are suggested and analyzed View full abstract»

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  • On the design of efficient video-on-demand broadcast schedules

    Publication Year: 1999 , Page(s): 262 - 269
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    In order to address the scalability problems of video-on-demand systems, several periodic broadcast schemes have been proposed that partition a video into segments and repetitively broadcast each segment on a separate channel. A new scheme is presented for the bandwidth-efficient periodic broadcast of video. The proposed scheme determines the segment sizes and their corresponding channel bandwidths as a result of a non-linear optimization problem which minimizes the total required bandwidth for the broadcast. The new scheme outperforms the existing schemes in terms of bandwidth demands while it also decouples the playout latency from the number of available channels. Further analysis reveals that its asymptotic bandwidth requirements exactly match the asymptotic bandwidth requirements reported for poly-harmonic broadcasting View full abstract»

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  • Towards performance analysis with partially symmetrical SWN

    Publication Year: 1999 , Page(s): 148 - 155
    Cited by:  Papers (1)
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    Stochastic well formed colored nets (SWN) make it possible to apply performance evaluation techniques on a compact representation of the reachability graph (RG), called the Symbolic RG (SRG). The Extended SRG (ESRG) has been proposed to achieve a higher degree of reduction when applied to partially symmetric SWN models. The price to pay for the more effective state space reduction, is a loss of information on the paths of the graph. Despite this loss, it has been shown that several qualitative properties can be studied on the ESRG. We consider the possibility of using the ESRG for performance evaluation purposes and more specifically, we explore how the ergodicity of the system can be decided on this graph View full abstract»

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  • Using ATM services for (in)efficient support of TCP

    Publication Year: 1999 , Page(s): 20 - 29
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    We study the performance of TCP/ABR and TCP/UBR as a function of the number of bottlenecks in an IP/ATM inter-networking system. We define an efficiency metric that captures the amount of badput generated per unit of goodput. We define a gain metric to be the ratio of the efficiencies of these two services. With these new metrics, we demonstrate that the bandwidth efficiency of TCP/ABR is scalable in the number of bottlenecks, whereas TCP/UBR is scalable only if there are no greedy sources in the traffic mix. We examine the influence of ABR and UBR on TCP factors such as packet loss, round trip time delays (RTTs), and the fraction of lost packets detected via fast retransmit events. We show that TCP/ABR is more efficient than TCP/UBR because the ABR control loop has favorable effects on the TCP control loop via its its influence on RTTs and loss behavior. We demonstrate that fairness has far reaching consequences beyond throughput fairness because the improvements to TCP in efficiency and scalability are a ramification of fairness View full abstract»

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  • Predicting behavior patterns using adaptive workload models [computer networks]

    Publication Year: 1999 , Page(s): 226 - 233
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    Workload characteristics in a modern networking environment are very dynamic. In order to maximize performance continuously, it is natural to explore the possibility of intelligent systems which can take cognizance of the workload dynamics and adapt themselves for future control applications. In this paper, we propose a mechanism which represents the previous state of the system as a string. The user is allowed to define relevant information for better management as substrings. The adaptive workload model, which is called the SVR model (named after the first author's initials), predicts the short-term future as a string in which the information content (conveyed as a substring) reflects the future. We illustrate the applicability of the SVR model through Web traffic generation and ATM bandwidth management. We use genetic algorithms as the vehicle to address the learning aspects of the model View full abstract»

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  • Analytical modelling of the network traffic performance

    Publication Year: 1999 , Page(s): 190 - 196
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    Interconnection network modeling is an important field in order to study and understand interconnection network behaviour and its significance in telecommunication applications and distributed systems. In this paper, we show an analytical model that represents interconnection networks. The model accepts as inputs the network load consisting of the network topology, routing, and the communication pattern of the application. Any topology of any size and different parameters for the router are supported. The model outputs the latency behaviour of the interconnection network for each channel on each link. The accuracy of the model is shown by comparison with network simulation. The model is useful to study the latency/load curve of communication patterns, to calculate average network delays to identify hot-spots in the network and to perform network analysis and design View full abstract»

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  • Evaluating concurrency options in software specifications

    Publication Year: 1999 , Page(s): 330 - 338
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    An approach called PERFECT is described which evaluates the feasibility of proposed software concurrency architectures for a set of scenarios and a set of quality-of-service requirements. An evaluation is performed by constructing and simulating a virtual implementation which conforms to the specified behaviour and the specified concurrency architecture. For simulation, the execution of application activities and kernel primitives must be sequenced for each concurrent thread. The approach is successfully demonstrated on specified scenarios for a group communication server View full abstract»

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  • Modeling memory reference patterns of programs in cache memory systems

    Publication Year: 1999 , Page(s): 288 - 295
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    Proposes a novel model to characterize the behavior of individual programs in the presence of cache memory. The model goes beyond the traditional hit/miss ratios often used in the current literature to describe program-cache interactions. Instead, it looks at the characteristics of the sequences of hits and misses during a program execution. The model includes several distributions that describe the hit and miss sequences. Several program characteristics which are otherwise not identified by the traditional models are discovered using our model. We then discuss how the model can be effectively used to tune the performance of a program, to allocate cache to a process, or to choose a cache architecture View full abstract»

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  • Simulation of broadband multiple access protocols for wireless networks

    Publication Year: 1999 , Page(s): 92 - 100
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    This paper describes the simulation of two broadband multiple access protocols. The protocols are modeled using OPNET. A formal verification for one of the protocols is also provided. The simulation models and verification procedures will be useful for network designers who wish to understand the operation of the two protocols View full abstract»

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  • Network simulations of a general class of partial-connection multiple-bus systems

    Publication Year: 1999 , Page(s): 120 - 127
    Cited by:  Patents (1)
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    A general class of optimal fault-tolerant partial-connection multiple-bus networks and their self-routing algorithms has been developed (Huan-yu Tu, 1999). By conducting a large number of network simulations, using self-similar traffic we compare the performance of these networks with those of traditional single-bus networks and complete-connection multiple-bus networks. Our simulation results show that given a fixed number of processors, these partial-connection networks have improved performance over single-bus systems, perform comparably to the more costly complete-connection multiple-bus systems, and have flexibility in setting the performance level and fault-tolerance level. Moreover, we demonstrate that, in certain of these networks, if the system load increases resulting in decreased performance, this can be handled by adding buses to the system rather than completely changing the topology. Thus, for very little additional cost and no change of topology or routing algorithm, increased loads are handled View full abstract»

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  • Performance evaluation of distributed co-ordination function for IEEE 802.11 wireless LAN protocol in presence of mobile and hidden terminals

    Publication Year: 1999 , Page(s): 40 - 47
    Cited by:  Papers (13)  |  Patents (6)
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    This paper investigates the performance of IEEE 802.11 wireless local area network (WLAN) protocol's distributed coordination function (DCF) in the presence of mobile and hidden terminals. In order to study the joint effect of hidden terminals and user mobility on the performance of IEEE 802.11 DCF, we extend Tobagi and Kleinrock's (1975) hearing graph framework to model hidden terminals in a static environment. We derive a combined mobility and hidden terminal model using a Markov chain from the hearing graph of a given physical layout. The simple model uses two parameters: α, which controls the number of hidden terminals in the steady state, and λ, which controls the rate of mobility of each terminal. By varying the values of α and λ we can systematically generate scenario with different number of hidden terminals and different mobility rates for a particular physical layout with static obstructions. We have developed a discrete event simulator which uses the parameterized model to obtain the throughput and blocking probability behavior of an IEEE 802.11 based ad hoc network in the presence of certain static obstructions. Our simulations suggest that the IEEE 802.11 DCF protocol is robust enough to handle moderate conditions of hidden terminals and mobility, but the performance may degrade under extreme conditions. Carefully selecting protocol parameters (RTS and fragmentation threshold) can help improve the performance even under extreme conditions View full abstract»

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  • Universal benchmark suites

    Publication Year: 1999 , Page(s): 197 - 205
    Cited by:  Papers (1)
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    We present theoretical concepts, design, and use of universal benchmark suites. Such suites consist of benchmark programs that represent all relevant characteristic types of workload. The execution times of individual benchmarks and appropriate weights can be used to compute global performance indicators that reflect a spectrum of specific compound workloads. All such global indicators can be obtained from the same universal benchmark suite. This approach substantially reduces the cost of benchmarking View full abstract»

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  • The SimUTC fault-tolerant distributed systems simulation toolkit

    Publication Year: 1999 , Page(s): 68 - 75
    Cited by:  Papers (2)
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    We introduce our SimUTC toolkit, a fault-tolerant distributed systems simulation built upon the discrete event simulation package C++SIM. SimUTC has been developed in the course of our project SynUTC and targets distributed algorithms for high-accuracy fault-tolerant clock synchronization. This application domain requires detailed simulation models for network transmission and local clock devices, fault-injection capabilities, flexible system configuration facilities, and customized data capture and analysis tools. We explain how SimUTC addresses those issues and provide a few samples of simulation results gathered from the evaluation of the well-known fault-tolerant average clock synchronization algorithm View full abstract»

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  • Modeling user behavior: a layered approach

    Publication Year: 1999 , Page(s): 218 - 225
    Cited by:  Papers (8)  |  Patents (1)
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    The simulation of computer systems requires representative, reliable workload models. When simulating computer systems or components that are influenced by user behavior, this very behavior has to be modeled by using mathematical means. In this article, we propose a user behavior model framework that is constructed in a top-down manner consisting of various layers. The layers offer services to the next higher layer and require services from the layers below. The framework is meant to enable the modeler to plug in his own models at the layers of his choice, thus choosing the right balance between the simulation complexity and creating representative results. We give a description of the layered framework and the corresponding methodology. The approach is then demonstrated on modeling HTTP traffic, to be used in network traffic simulation View full abstract»

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  • Analysis of self-similarity in I/O workload using structural modeling

    Publication Year: 1999 , Page(s): 234 - 242
    Cited by:  Papers (15)
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    Demonstrates that disk-level I/O requests are self-similar in nature. We show evidence (both visual and mathematical) that I/O accesses are consistent with self-similarity. For this analysis, we have used two sets of disk activity traces collected from various systems over different periods of time. In addition to studying the aggregated I/O workload that is directed to the storage system, we perform a structural modeling of the workload in order to understand the underlying causes that produce the observed self-similarity. This structural modeling shows that self-similar behavior can be explained by combining two different approaches: the on/off source model and Cox's model. The former applies to those processes that remain active during the whole trace, while the latter applies to sources that show a very short activity time View full abstract»

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  • SDH digital cross-connect traffic generation algorithm

    Publication Year: 1999 , Page(s): 84 - 91
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    Synchronous digital hierarchy (SDH) customers require complex connections, and cross-connect manufacturers attempt to design switching architectures and algorithms-referred henceforth as cross-connect systems-that will meet these needs. However, the designs are constrained by physical and economic considerations. Thus, the manufacturers are forced to restrict the capabilities of their designs. Such design decisions impact the customers' abilities to transmit and receive certain combinations of traffic. Simulations may be executed to evaluate the impact of the design compromises on the performance of the SDH digital cross-connect. Realistic SDH traffic, which may be utilized as inputs to these SDH switching simulations, is the desired result of this research. This paper summarizes and analyzes an algorithm that produces such connection requests View full abstract»

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  • Jump transitions in second order FSPNs

    Publication Year: 1999 , Page(s): 156 - 163
    Cited by:  Papers (3)
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    In this paper jump transitions for the fluid model part in second order fluid stochastic Petri nets (FSPNs) are introduced. The extended formalism is defined, and the underlying partial differential equations are derived. With a jump a certain amount of fluid is added to a fluid place or taken out at once. This amount, the jump height, is sampled from a probability distribution. The dynamics of a model are described by second order partial differential equations that include integrals. As examples the virtual waiting time (or unfinished work) in a queueing system and a performability model of a multi-processor system are modelled View full abstract»

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  • Modeling overhead in servers with transactional workloads

    Publication Year: 1999 , Page(s): 182 - 189
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    Our research focuses on reducing the computing time in large simulation models of client-server architectures by replacing server models by load dependent servers (LDSs), whose solution requires less computational effort. As these LDSs include overhead information, it is necessary to design a set of measurements for collecting overhead data. We are proposing a methodology that indicates how to reduce the amount of measurements and how to model overhead by means of regression analysis. In this work we explain how the methodology is applied to a workload composed of TPC-C transactions that runs in a server with Solaris 2.5 operating system (OS). Also, we describe the construction of the LDS. We compare the LDS predictions with measurements of the TPC-C benchmark View full abstract»

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  • Feature interaction as a satisfiability problem

    Publication Year: 1999 , Page(s): 339 - 346
    Cited by:  Papers (1)
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    We present a formal model for the specification of telephone features by means of description logics. Our framework permits the formal definition of the basic telephone system as well as the specification of additional features (call waiting, call forwarding, etc.). Furthermore, by using standard reasoning tasks from description logics, the properties of features can be formally proved and interactions detected. An EXPTIME upper bound for the complexity of detecting feature interaction as a satisfiability problem is provided by exploiting well-known results for expressive description languages View full abstract»

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