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Performance, Computing and Communications, 1998. IPCCC '98., IEEE International

Date 16-18 Feb. 1998

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Displaying Results 1 - 25 of 60
  • 1998 IEEE International Performance, Computing and Communications Conference. Proceedings (Cat. No.98CH36191)

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    Freely Available from IEEE
  • Author index

    Page(s): 0_20
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    Freely Available from IEEE
  • New network QoS measures for FEC-based audio applications on the Internet

    Page(s): 355 - 362
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    New network QoS (quality of service) measures for interactive audio applications using FEC (forward error control) are proposed. Applications such as an Internet phone require both low data loss and a short delay for the underlying transport layer. The FEC-based error control has become popular as a way of meeting such requirements; new application data (or highly compressed data) are copied onto successive packets, so that random packet losses in networks can be concealed to some extent. From the viewpoint of FEC-based applications, actual QoS depends not only on the loss and delay of each packet, but also on the loss and delay of successive packets. Conventional network QoS measures such as loss rate and delay distribution, however, only focus on each packet. Therefore, the probability of long successive losses, for example, cannot be monitored, even though they strongly affect FEC-based application QoS. We propose a new concept named “loss window size” for measuring the QoS of successive packets. Definitions of loss and delay are generalized using this concept. These definitions take the FEC-based error concealment into account. Therefore, these measures enable more precise estimation of FEC-based application-level QoS than conventional measures. In order to show the effectiveness of the proposed measures, we have built an experimental monitoring system on working networks. The actual data show that network QoS may vary from time to time in terms of newly defined measures, even though QoS variation using conventional measures are not so apparent. We also model FEC-based application QoS, and show that application QoS and proposed network measures correspond well View full abstract»

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  • Near optimal broadcast in all-port wormhole routed hypercubes using error correcting codes

    Page(s): 8 - 14
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    A new broadcasting method is presented for hypercubes with wormhole routing mechanism. The approach is based on determination of the set of nodes (called stations) in the hypercube such that for any node in the network there is a station at distance of at most 1. Once stations are identified, parallel disjoint paths are formed from the source to all stations. The broadcasting is accomplished first by sending the message to all stations which will in turn inform the rest of the nodes of the message. To establish node-disjoint paths between the source node and all stations, we introduce a new routing strategy. We prove that multicasting can be done in one routing step as long as the number of destination nodes are fewer than or equal to n in an n-dimensional hypercube. The number of broadcasting steps using our routing is equal to or smaller than that obtained in an earlier work View full abstract»

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  • Scalability of wavelength division multiplexed optical passive star networks with range limited tunable transceivers

    Page(s): 86 - 93
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    The size of an optical passive star and the wavelength range of tunable optical transceivers is limited by current technology. Scalability of passive star networks built with these two limitations is thus an important issue for building large networks. Previously, Cao, Du and Pavan (see Technical Report, Department of Computer Science, University of Minnesota, 1996) explored the design issues for single star networks employing transceivers with limited tuning range. Here we extend that study by considering the problem of connecting several optical passive stars, each embedded with a given virtual topology, to create larger aggregate networks. The design issues are analyzed and a number of design rules are proposed for building such aggregate networks. We consider the most commonly employed virtual topologies-complete graph, mesh and hypercube View full abstract»

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  • PLAN: a pipeline-access local ATM network protocol for multimedia applications

    Page(s): 379 - 385
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    This paper presents a shared media ATM LAN architecture known as pipelined-access local ATM network (PLAN) suitable for both LAN and MAN applications. It is a reservation type bi-directional broadcast bus system protocol in which stations are connected at predefined points on the bus and all transmissions are done sequentially from one end to the other in a pipelined manner. It is designed to (i) support multimedia traffic, (ii) dynamically allocate bandwidth to various types of traffic and provide fair media access to stations, (iii) provide throughput close to 100%, (iv) operate at high bit rates, and, (v) use packets of ATM cell size and format for interoperability with the wide-area ATM networks. We present the architecture, analysis and performance of the proposed PLAN protocol under various multimedia traffic conditions. The results show that its throughput approaches 100%, is independent of traffic composition, and increases slowly with bit rate. It decreases only slightly as the bus length and/or number of stations increases. For example, the throughput decreases only by 0.17% per kilometer as the bus length increases. Based on the results obtained, the proposed PLAN protocol is seen to be well suited for high speed multimedia ATM LAN and MAN applications View full abstract»

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  • Threshold-based admission control for multi-class video-on-demand systems

    Page(s): 154 - 160
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    The next generation of distributed digital video-on-demand (VoD) systems will use admission control tests to ensure that users receive predictable and guaranteed service. If the system cannot support a new request then that request is blocked This paper presents an analytical model to evaluate unified admission control strategies for distributed VoD systems with multiple video classes. We prove that there exists a computationally efficient technique to determine the blocking probabilities for newly arriving requests. Through numerical analysis we show the effect of different admission control policies on overall system blocking rates View full abstract»

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  • A lower bound for quantifying overlap effects: an empirical approach

    Page(s): 253 - 259
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    Among the many features that are implemented in today's microprocessors there are some that have the capability of reducing the execution time via overlapping of different operations. Overlapping of instructions with other instructions and overlapping of computation with memory activities are the main way in which execution time is reduced. In this paper we will introduce a notion of overlap and its definition, and a few different ways to capture its effects. We will characterize some of the ASCI benchmarks using the overlap and some other quantities related to it. Also, we will present a characterization of the overlap effects using a lower bound derived empirically from measured data. We will conclude by using the lower bound to estimate other components of the overall execution time View full abstract»

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  • Performance analysis of shared buffer ATM switch with different cell departure models

    Page(s): 386 - 392
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    The performance analysis of an asynchronous transfer mode (ATM) switch involves modeling the input traffic source, the switching mechanism, and the cell departure process. A main issue which determines the overall accuracy in performance evaluation of ATM switch, is the use of an appropriate probabilistic model to describe the cell departure process. Until now, little work has been done in the literature on characterizing the cell departure process for studying the performance of an ATM switch. This paper compares and verifies the accuracy of several models, including a new one called the “Urn model”, which we propose. These models are put under test in a performance evaluation of a shared buffer ATM switch, by using a discrete-time Markov chain. The numerical results are compared to the simulation, and they show that the Urn model is a good compromise between accuracy and efficiency. This finding is significant because it helps to speed up the running of an analytical model of a large network while providing satisfactory accuracy View full abstract»

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  • Bounds-based loop performance analysis: application to validation and tuning

    Page(s): 178 - 184
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    We consider the floating point microarchitecture support in high-end RISC superscalar processors. We propose a simple, yet effective bounds model to deduce the “bestcase” loop performance limits for these processors. We compare these bounds to simulation-based (and where available, hardware-based) performance measurements for actual compiler-generated code sequences. From this study, we identify loop tuning opportunities to bridge the gap between “best-case” and “actual” performance in a post-silicon setting. Some of the results of such analysis point to fundamental hardware performance bugs which may be removed through feasible microarchitectural changes. More frequently, the analysis is useful for suggesting compiler enhancements. The analysis methods described have been used in actual high-end processor development projects within our company. We report our experimental results in the context of a set of application-based loop test cases, designed to stress various resource limits in the core (infinite cache) microarchitecture View full abstract»

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  • VCR functionality in transmission of MPEG video over CBR channel

    Page(s): 133 - 139
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    Different techniques for providing VCR-type functions, such as fast-forward and fast-reverse, are developed for transmission of pre-encoded MPEG video over constant-bit-rate (CBR) channels. Computer simulations using eight MPEG-1 movies showed that the receiver buffer size can be kept small even if VCR functionality is supported in the system. A simple call admission control algorithm is also developed to remain a fairly high network utilization when all VCR functions are provided View full abstract»

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  • A simple hierarchical traffic model for VBR MPEG video

    Page(s): 147 - 153
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    A hierarchical model is derived for MPEG video. This model is developed so as to represent the bit-rate variations of MPEG video at two different time scales/levels: scene level and frame level. Various evaluations show that the proposed model not only matches very good the statistical characteristics with the real MPEG video but also predicts accurately the network performance of an ATM multiplexer View full abstract»

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  • A practical building block for solving agreement problems in asynchronous distributed systems

    Page(s): 25 - 31
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    Providing processes with the same view of a global state or allowing them to take consistent decisions, despite asynchrony and failure occurrences, are fundamental problems encountered in distributed systems. These problems are called agreement problems. Non blocking atomic commitment and definition of a single delivery order for broadcast messages are examples of such problems. We define a paradigm (called Single Global View) that encompasses various practical agreement problems. The interest of this paradigm lies in its practicability: each process starts with an initial value, and all these values are pieced together in such a way that, despite process crashes and asynchrony, all correct processes are delivered the same set of values (namely, the Single Global View). The power of this paradigm is the same as that of the consensus problem defined by theoreticians. Instantiations of the paradigm, which solve practical agreement problems, are given. A protocol implementing the paradigm is also presented View full abstract»

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  • The effects of user mobility on usage parameter control (UPC) in wireless ATM systems

    Page(s): 216 - 221
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    Wireless asynchronous transfer mode (WATM) networks pose new traffic management problems. One example is the effect of user mobility on usage parameter control (UPC). If the UPC algorithm resets after each handoff between wireless-cells, then users can cheat on their traffic contract. In brief, UPC is analogous to a digital filtering operation, with an associated convergence time. If a user changes wireless-cells before the UPC algorithm converges then UPC can not determine whether that user complied with their traffic contract. This paper derives explicit relationships between a user's traffic parameters (peak cell rate, sustained cell rate and maximum burst size), their transit time per wireless-cell, their maximum sustained cheating-rate and the generic cell rate algorithm's (GCRAs) limit (L) parameter. It also shows that the GCRA can still effectively police constant bit rate (CBR) traffic, but not some types of realistic variable bit rate (VBR) traffic. Finally, it discusses three solutions for this new network impairment View full abstract»

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  • Access paths and testing in an ultra high-performance ATM switch

    Page(s): 373 - 378
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    This paper discusses the architecture and testing of an ultra high performance 4-input, 4-output asynchronous transfer mode (ATM) switch that has been designed as part of the DARPA-sponsored “Thunder and Lightning” project at the University of California, Santa Barbara. This research project is focused on the design and prototype demonstration of ATM links and switches operating at or above 40 gigabits per second per link (TDM), with potential scalability to 100 Gbit/sec. Such aggressive link rates place severe requirements on switch architecture, particularly the buffering scheme. We discuss the access paths and test techniques used in the development and verification of this electronic ATM switch and describe reasons for the main design choices View full abstract»

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  • Scalable multicast data distribution for different transport service classes

    Page(s): 435 - 441
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    Not all of the problems of large scale multicast can be addressed by automated repeat request (ARQ) based multicast protocols. Simulation studies have shown that independent packet loss among receivers is a worst case situation, where ARQ based protocols scale poorly and react with throughput degradation. Software based forward error correction (FEC) techniques are therefore a good solution and can be used to enhance the throughput efficiency by controlling the packet loss rate. A new method for implementing FEC at the transport layer is presented and performance measurements are shown. The difference between the restricted reliable multicast protocol (RRMP) and existing ARQ/FEC based multicast protocols is the flexibility and adaptability the RRMP provides by offering different transport service classes for different application needs. An application is able to choose the transport service, which best meets the requirements for efficiency, latency, delay, scalability etc. The design and implementation decisions for the FEC and ARQ based error recovery are outlined. Performance measurements demonstrate the suitability of FEC for real-time data transmissions View full abstract»

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  • The effect of object-agent interactions on the performance of CORBA systems

    Page(s): 67 - 74
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    The notion of middleware has been introduced to provide interoperability as well as transparent location of servers in heterogeneous client server environments. Although such benefits accrue from the use of middleware, careful consideration of system architecture is required to achieve high performance. Based on implementation and measurements made on the system, the paper is concerned with the impact of client agent server interaction architecture on the performance of a CORBA System. CORBA or Common Object Request Broker Architecture proposed by the Object Management Group is one of the commonly used standards for middleware architecture. Using a commercially available CORBA compliant ORB software called ORBeline, we have implemented two different architectures for client agent server interaction on a network of workstations. In the Handle Driven ORB architecture the client gets the address of the server from the agent and communicates with the server directly. In the Forwarding ORB architecture the client request is automatically forwarded by the agent to the appropriate server which then returns the results of the computations to the client. Our measurements show that the differences among the performance of these architectures change with a change in the workload. The paper reports on the relative performance of the two architectures under different workload conditions. The results provide insights into system behavior. In particular the impact of message size on the latency and scalability attributes of these architectures is analyzed. A discussion of how agent cloning can improve system performance is also included View full abstract»

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  • Passive testing of networks using a CFSM specification

    Page(s): 111 - 116
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    We introduce a variant of the communicating finite state machine model for the specification of networks in order to determine correct or faulty behavior using passive testing. The appropriateness of the model is first argued, followed by an initial study of how the passive testing procedures developed for finite state machines could be applied. Approaches for, and limitations of, fault detection and fault location using this approach are discussed View full abstract»

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  • Bandwidth-guaranteed IP tunneling router with RSVP

    Page(s): 291 - 297
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    The Internet Engineering Task Force is standardizing the resource reservation protocol (RSVP) to reserve network resources over TCP/IP networks. End-to-end resource reservation with RSVP requires that RSVP is implemented in all nodes on the path. However, traffic control algorithms for resource reservation are complex in general, so it takes a long time for all nodes including end nodes to support them. Previously, it has been proposed that RSVP be used to guarantee sufficient bandwidth for a virtual private network over a TCP/IP network. The authors consider that the characteristics of traffic within a VPN are similar to the one outside a VPN, and consider only bandwidth as a major network resource parameter. Under these assumptions, the authors proposed a lightweight traffic control algorithm for bandwidth-guaranteed VPN and developed a router with this algorithm. This paper shows the results of an evaluation of this algorithm with pseudo-traffic generated by a specially designed traffic generator based on real traffic, and also shows that the bandwidth for VPN will be guaranteed in the normal VPN environment View full abstract»

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  • MPEG-2 as a transmission system for Internet traffic

    Page(s): 101 - 107
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    MPEG-2 is an international standard defining compression algorithms for video and audio. Additionally, the standard defines a packet and cell oriented transmission system for the resulting digital streams. This system has been used as a local network to carry Internet traffic over a direct broadcast satellite. Applications have been developed for either unicast or multicast services from a base station server to a group of receiving clients. Inexpensive integrated receiver/decoder cards are used which contain a complete RF receiver, demodulator and decoder and interface directly to the PC bus. The paper describes the encapsulation and the implementation of a prototype system based on the European DVB standards which has been operational since early 1997. It then discusses some of the design decisions and suggests a generic encapsulation mechanism for future data and multimedia applications using MPEG-2 as a transport system View full abstract»

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  • Performance optimisation evaluation of TCP/IP over wireless networks

    Page(s): 395 - 401
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    The transmission control protocol (TCP) is a large extended transport protocol, mainly used in fixed networks. It works well in those networks in which the main cause of packet loss is congestion. Some mechanisms included in the TCP optimise their use in this kind of networks. Today, Internet users need access it over wireless links in order to get this service anywhere they are. However, the TCP does not work well in wireless environments where losses are due to high bit error rates (BER). We evaluate the end-to-end throughput of a TCP connection with a wireless link. First, we demonstrate the impact of high BER in the TCP performance. Then, we optimise the throughput of the TCP connection choosing the best MTU (maximum segment size) in each case, and evaluate other aspects of interests View full abstract»

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  • Dynamic resource allocation in ATM networks

    Page(s): 328 - 335
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    This paper is principally concerned with dynamic resource allocation in ATM networks. When designing and configuring an ATM network, it remains difficult to guarantee the quality of service (QoS) for different connections, this needs more advanced functions to monitor the current situation, determine the required resource, allocate the resource, and modify it. In this paper, we introduce a dynamic resource allocation metric, based on probabilistic tools, which serves as a monitoring mechanism of resource allocation View full abstract»

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  • Accurate measurement of system call service times for trace-driven simulation of memory hierarchy designs

    Page(s): 239 - 244
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    This paper presents a methodology for accurately measuring system call service times and process blocking times in a UNIX-like computing environment. Problems that may cause inaccurate measurements stem from the method used to charge processes for execution time, the difference in the time consumed during a system call and a time quantum or dispatch interval, and the instrumentation overhead included in the measurement program. The collected measurements for each system call are used to form a distribution from which process blocking times can be drawn or for which the mean can be used as the process blocking time View full abstract»

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  • Estimation of error blocks in SDH networks

    Page(s): 339 - 345
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    In this paper, we study bit interleaved parity (BIP) code performance based on the features of BIP code. We find the closed form by applying the binomial theorem to solve the undetected error probability when even parity is used for detecting transmission errors in SDH networks. We estimate BIP code performance and calculate the theoretical and detected values of block error rate according to the formulae recommended by ITU-T and amended by us. From a group of curves related to them, we study the numerical results. Our method provides a new choice for performance analysis of error blocks in SDH network, that is simpler than previous methods View full abstract»

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  • Channel reification: a reflective model for distributed computation

    Page(s): 32 - 36
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    The paper presents a new reflective model, called Channel Reification, which can be used in distributed computations to overcome difficulties experienced by other models in the literature when monitoring communication among objects. The channel is an extension of the message reification model. A channel is a communication manager incarnating successive messages exchanges by two objects: its application ranges between those of message reification and those of meta object model. After a brief review of existing reflective models and how reflections can be used in distributed systems, channel reification is presented and compared to the widely used meta object model. Applications of channel reification to protocol implementation, and to fault tolerant object systems are shown. Future extensions to this model are also summarized View full abstract»

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