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Network Resources (network + resource)
Selected AbstractsNetwork Resources for Internationalization: The Case of Taiwan's Electronics Firms*JOURNAL OF MANAGEMENT STUDIES, Issue 5 2003Tain-Jy Chen ABSTRACT This paper illustrates foreign direct investment (FDI) as the management of important network relations, using Taiwan's electronics firms as an example. Through FDI, seemingly small and weak firms propel the process of internationalization by making maximum use of external resources to which they have access. FDI often starts at a location close to the home base where support from the domestic networks can be drawn, subsequently moving on to more distant locations after investors have accumulated new network resources. The location chosen is usually an area rich in network resources or in close proximity to such rich networks. FDI enables the investors to construct a regional, or even global, sub-network under their control to supply a set of wide-ranging, differentiated and low-cost products in a flexible fashion, and sometimes within close proximity to the markets. With this capacity for versatility, investors become valuable partners for multinational firms that offer global services. [source] Network-aware selective job checkpoint and migration to enhance co-allocation in multi-cluster systems,CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 13 2009William M. Jones Abstract Multi-site parallel job schedulers can improve average job turn-around time by making use of fragmented node resources available throughout the grid. By mapping jobs across potentially many clusters, jobs that would otherwise wait in the queue for local resources can begin execution much earlier; thereby improving system utilization and reducing average queue waiting time. Recent research in this area of scheduling leverages user-provided estimates of job communication characteristics to more effectively partition the job across system resources. In this paper, we address the impact of inaccuracies in these estimates on system performance and show that multi-site scheduling techniques benefit from these estimates, even in the presence of considerable inaccuracy. While these results are encouraging, there are instances where these errors result in poor job scheduling decisions that cause network over-subscription. This situation can lead to significantly degraded application performance and turnaround time. Consequently, we explore the use of job checkpointing, termination, migration, and restart (CTMR) to selectively stop offending jobs to alleviate network congestion and subsequently restart them when (and where) sufficient network resources are available. We then characterize the conditions and the extent to which the process of CTMR improves overall performance. We demonstrate that this technique is beneficial even when the overhead of doing so is costly. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dimensioning of data networks: a flow-level perspectiveEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2009Pasi Lassila Traditional network dimensioning formulations have applied the Erlang model where the connections reserve capacity in the network. Until recently, tractable stochastic network models where the connections share the capacity in the network did not exist. The latter are becoming increasingly important as they can be applied to characterise file transfers in current data networks (e.g. IP networks). In particular, they can be utilised for dimensioning of networks with respect to the file transfer performance. To this end, we consider a model where the traffic consists of elastic flows (i.e. file transfers). Flows arrive randomly and share the network resources resulting in stochastically varying transmission rates for flows. Our contribution is to develop efficient methods for capacity planning to meet the performance requirements expressed in terms of the average transmission rate of flows on a given route, i.e. the per-flow throughput. These methods are validated using ns2 simulations. We discuss also the effects of access rate limitations and how to combine the elastic traffic requirements with those of real-time traffic. Finally, we outline how the methods can be applied in wireless mesh networks. Our results enable a simple characterisation of the order-of-magnitude of the required capacities, which can be utilised as a first step in practical network planning and dimensioning. Copyright © 2008 John Wiley & Sons, Ltd. [source] A network-centric approach for access and interface selection in heterogeneous wireless environmentsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2008George Koundourakis Abstract In this paper, we introduce a network-based approach for access and interface selection (AIS) in the context of resource management in heterogeneous wireless environments (UMTS, WLAN and DVB-T). We focus on the optimization of resource utilization, while ensuring acceptable quality of service (QoS) provision to the end users. Our objective is to optimally manage the overall system resources and minimize the possibility of QoS handovers (non-mobility handovers). The adopted architecture applies to typical heterogeneous environments and network entities (Access Routers) are enhanced with extra functionalities. We propose an AIS algorithm that exploits the multihoming concept and globally manages network resources at both radio access and IP backbone networks. The algorithm can estimate near-optimal solutions in real time and we also introduce a novel triggering policy. We present simulation results of typical scenarios that demonstrate the advantages of our approach. System performance metrics, derived from the simulations, show minimum degradations in high load and congestion situations. Copyright © 2007 John Wiley & Sons, Ltd. [source] Competitive flow control in general multi-node multi-link communication networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2008Ismet Sahin Abstract In this paper, we consider the flow control in a general multi-node multi-link communication network with competing users. Each user has a source node, a destination node, and an existing route for its data flow over any set of links in the network from its source to its destination node. The flow rate for each user is a control variable that is determined by optimizing a user-specific utility function which combines maximizing the flow rate and minimizing the network congestion for that user. A preference parameter in the utility function allows each user to adjust the trade-off between these two objectives. Since all users share the same network resources and are only interested in optimizing their own utility functions, the Nash equilibrium of game theory represents a reasonable solution concept for this multi-user general network. The existence and uniqueness of such an equilibrium is therefore very important for the network to admit an enforceable flow configuration. In this paper, we derive an expression for the Nash equilibrium and prove its uniqueness. We illustrate the results with an example and discuss some properties and observations related to the network performance when in the Nash equilibrium. Copyright © 2007 John Wiley & Sons, Ltd. [source] Non-inferior Nash strategies for routing control in parallel-link communication networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2005Yong Liu Abstract We consider a routing control problem of two-node parallel-link communication network shared by competitive teams of users. Each team has various types of entities (traffics or jobs) to be routed on the network. The users in each team cooperate for the benefit of their team so as to achieve optimal routing over network links. The teams, on the other hand, compete among themselves for the network resources and each has an objective function that relates to the overall performance of the network. For each team, there is a centralized decision-maker, called the team leader or manager, who coordinates the routing strategies among all entities in his team. A game theoretic approach to deal with both cooperation within each team and competition among the teams, called the Non-inferior Nash strategy, is introduced. Considering the roles of a group manager in this context, the concept of a Non-inferior Nash strategy with a team leader is introduced. This multi-team solution provides a new framework for analysing hierarchically controlled systems so as to address complicated coordination problems among the various users. This strategy is applied to derive the optimal routing policies for all users in the network. It is shown that Non-inferior Nash strategies with a team leader is effective in improving the overall network performance. Various types of other strategies such as team optimization and Nash strategies are also discussed for the purpose of comparison. Copyright © 2005 John Wiley & Sons, Ltd. [source] Improving node behaviour in a QoS control environment by means of load-dependent resource redistributions in LANs,INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2005Bernd E. Wolfinger Abstract An important means to guarantee an acceptable quality of service in networks with real-time communication requirements is the reservation of resources at connection setup time. However, such reserved resources, e.g. transmission bandwidth, may be unused as a consequence of the variations in the actual resource demands. Therefore, a more efficient resource utilization is possible if communicating stations or end-users dynamically hand over some of the free resources temporarily to the other communication partners, e.g. of a ,broadcast network'. This paper concentrates on two fundamental problems of such a demand-based sharing of resources: on the one hand, estimation of the current resource requirement on the basis of load measurements is investigated and, on the other hand, we elaborate efficient algorithms for resource sharing respecting real-time requirements. The algorithms proposed for load estimation and for resource sharing are evaluated analytically with respect to their efficiency for worst-case, average-case and realistic load scenarios. Our approach suggested for resource and traffic management allows one to achieve significantly better utilization of network resources. Copyright © 2005 John Wiley & Sons, Ltd. [source] Performance issues of bandwidth management in ATM networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2003Christos Bouras Abstract In our days, efficient management of the available network resources becomes a critical issue, both from a functional point of view (so that users can be provided with the bandwidth they need), and an economical point of view (so that carriers can satisfactorily and efficiently serve as many customers as possible and at the same time increase their revenue). In this paper we consider a bandwidth control scheme (i.e. managed bandwidth service) for an ATM network infrastructure which is applied to the Greek research and technology network (GRNET). We present some methods that we have tested (in a simulation setting) in order to increase the efficiency of the system and the utilization of the available bandwidth. More specifically, we consider a bandwidth-resizing algorithm for virtual paths, in order to keep the allocated bandwidth very close to the bandwidth actually used. This leads to an increased number of accepted requests and better network utilization. We, also, use the simulation results in order to get an estimation of the effective bandwidth for VBR paths that can be used in call admission. Finally, we consider a semi-offline scheme where requests are gathered and considered for acceptance in regular intervals. Simulation results show an increase in the utilization of resources. As a further improvement, we allow connections to be allocated a little before or after the time initially requested. This leads to further improvement in network utilization. All the improvement schemes were tested with the ATM-TN simulator and the results look promising. Copyright © 2003 John Wiley & Sons, Ltd. [source] EVA: a better TCP version for resource-insufficient networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2002Jung-Shian Li Abstract TCP Vegas exhibits unfair congestion avoidance mechanism, which aggravates when there are insufficient network resources to accommodate buffer space of a pipe (bandwidth delay product). To remedy this shortcoming, we propose an Enhanced VegAs (EVA) that employs three auxiliary mechanisms: , revision, congestion detection and congestion tendency detection. A 2k factorial design with replications is used to study the effect of the three mechanisms. Our results show that TCP EVA achieves better performance than Vegas under various network conditions. Furthermore, congestion avoidance schemes, such as TCP EVA, perform much better than congestion control schemes, such as TCP Reno, in resource-insufficient networks. Copyright © 2002 John Wiley & Sons, Ltd. [source] Extending critical bandwidth allocation techniques for stored video delivery across best-effort networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2001Wu-chi Feng Abstract In this paper, we propose two new techniques for the delivery of compressed prerecorded video streams across best-effort networks like the Internet. Current approaches for the delivery of stored video across best-effort networks typically alter the quality of the video frames, the frame rate delivered to the user, or a combination of both. By using network feedback, these algorithms continually adjust the video quality to fit within the available network resources. These approaches, however, do not take advantage of the a priori information available from stored video streams, namely the frame sizes that the movie consists of. We will show how monitoring the a priori information and actively monitoring a client-side buffer can help smooth the video frame rate delivered to the user, providing a more consistent quality of video. Copyright © 2001 John Wiley & Sons, Ltd. [source] Automated application component placement in data centers using mathematical programmingINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2008Xiaoyun Zhu In this article we address the application component placement (ACP) problem for a data center. The problem is defined as follows: for a given topology of a network consisting of switches, servers and storage devices with varying capabilities, and for a given specification of a component-based distributed application, decide which physical server should be assigned to each application component, such that the application's processing, communication and storage requirements are satisfied without creating bottlenecks in the infrastructure, and that scarce resources are used most efficiently. We explain how the ACP problem differs from traditional task assignment in distributed systems, or existing grid scheduling problems. We describe our approach of formalizing this problem using a mathematical optimization framework and further formulating it as a mixed integer program (MIP). We then present our ACP solver using GAMS and CPLEX to automate the decision-making process. The solver was numerically tested on a number of examples, ranging from a 125-server real data center to a set of hypothetical data centers with increasing size. In all cases the ACP solver found an optimal solution within a reasonably short time. In a numerical simulation comparing our solver to a random selection algorithm, our solver resulted in much more efficient use of scarce network resources and allowed more applications to be placed in the same infrastructure. Copyright © 2008 John Wiley & Sons, Ltd. [source] Measuring the edge-to-edge available bandwidth in a DiffServ domainINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 5 2008N. Blefari-Melazzi The new Internet will be deployed with a number of tools for network management and quality of service control. To this end, we focus on a single administrative domain based on the Differentiated Services architectural model, and we recognize the need for two main functions for each supported traffic class: an admission control procedure, and a monitoring of the edge-to-edge bandwidth availability. In this work, we specifically focus on the second issue. To preserve scalability and thus to be compliant with Differentiated Services architecture, we propose stateless and distributed procedures based on traffic measurements. Our technique tests network resources by means of ,special' probing packets, which have the task of implicitly conveying the network status to its edges. We show by means of simulations the effectiveness of our solutions, in spite of a very low overhead. Copyright © 2007 John Wiley & Sons, Ltd. [source] Dynamic scheduling of network resources with advance reservations in optical gridsINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 2 2008Savera Tanwir Advance reservation of lightpaths in grid environments is necessary to guarantee QoS and reliability. In this paper, we have evaluated and compared several algorithms for dynamic scheduling of lightpaths using a flexible advance reservation model. The main aim is to find the best scheduling policy for a grid network resource manager that improves network utilization and minimizes blocking. The scheduling of lightpaths involves both routing and wavelength assignment. Our simulation results show that minimum-cost adaptive routing where link costs are determined by the current and future usage of the link provides the minimum blocking. For wavelength assignment, we have used a scheme that reduces fragmentation by minimizing unused gaps. We have also analyzed approaches for failure recovery and resource optimization. Copyright © 2008 John Wiley & Sons, Ltd. [source] An efficient architecture for Bandwidth Brokers in DiffServ networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2008Ch. Bouras In this article we examine the architecture of an entity used for automatic management and provisioning of resources for DiffServ networks. We examine the existing literature and implementations in this area, focusing on the design choices made, and we propose an architecture for the design of Bandwidth Brokers that combines an adaptive admission control algorithm for increased utilization of network resources and a mechanism for reducing the complexity overhead that intends to be both simple and effective. Specifically, we present a novel architecture for the admission control module that aims at achieving a satisfactory balance between maximizing the resource utilization for the network provider and minimizing the overhead of the module. We complement our theoretical discussion with extensive experimental simulations for the proposed Bandwidth Broker components and analysis of the results. The simulations study the possible configurations of the proposed algorithm and also compare it with alternative admission control policies. Copyright © 2007 John Wiley & Sons, Ltd. [source] Integrating the scene length characteristics of MPEG video bitstreams into a direct broadcast satellite network with return channel systemINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2004Fatih Alagöz Abstract In order to optimize the network resources, we should incorporate all the available information into the network design. However, incorporating irrelevant information may increase the design complexity and/or decrease the performance of the network. In this paper, we investigate the relevance of integrating the scene length characteristics of moving pictures expert group (MPEG) coded video bitstreams into a direct broadcast satellite (DBS) network with return channel system (DVB-RCS). Due to the complexity of the studied system, unless disputable simplifications are made, it is hard to achieve a mathematical foundation for this integration. Our analysis relies on extensive set of simulations. Firstly, we achieve the scene length distributions for MPEG bitstreams based on the proposed scene change models and their subjective observations of the actual video. We show that these models may be used to estimate the scene length of MPEG bitstreams. We then integrate this estimation into a DBS network simulator. Finally, we show that the scene length characteristics may be used to improve the DBS network performance under certain conditions. Copyright © 2004 John Wiley & Sons, Ltd. [source] TCP-Peach for satellite networks: analytical model and performance evaluationINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2001Ian F. Akyildiz Abstract Current TCP protocols have low throughput performance in satellite networks mainly due to the effects of long propagation delays and high link error rates. TCP-Peach is a new congestion control scheme for satellite IP networks based on the use of low priority segments, called dummy segments. The sender transmits dummy segments to probe the availability of network resources. Dummy segments are treated as low priority segments thus, they do not effect the throughput of actual data segments. In this paper, TCP-Peach is presented along with its analytical model which is used to evaluate the throughput performance. Experiments show that TCP-Peach is robust to high link error rates as well as long propagation delays, and outperforms other TCP schemes for satellite networks. Copyright © 2001 John Wiley & Sons, Ltd. [source] Network Resources for Internationalization: The Case of Taiwan's Electronics Firms*JOURNAL OF MANAGEMENT STUDIES, Issue 5 2003Tain-Jy Chen ABSTRACT This paper illustrates foreign direct investment (FDI) as the management of important network relations, using Taiwan's electronics firms as an example. Through FDI, seemingly small and weak firms propel the process of internationalization by making maximum use of external resources to which they have access. FDI often starts at a location close to the home base where support from the domestic networks can be drawn, subsequently moving on to more distant locations after investors have accumulated new network resources. The location chosen is usually an area rich in network resources or in close proximity to such rich networks. FDI enables the investors to construct a regional, or even global, sub-network under their control to supply a set of wide-ranging, differentiated and low-cost products in a flexible fashion, and sometimes within close proximity to the markets. With this capacity for versatility, investors become valuable partners for multinational firms that offer global services. [source] Fault-tolerant control of process systems using communication networksAICHE JOURNAL, Issue 6 2005Nael H. El-Farra Abstract A methodology for the design of fault-tolerant control systems for chemical plants with distributed interconnected processing units is presented. Bringing together tools from Lyapunov-based nonlinear control and hybrid systems theory, the approach is based on a hierarchical architecture that integrates lower-level feedback control of the individual units with upper-level logic-based supervisory control over communication networks. The local control system for each unit consists of a family of control configurations for each of which a stabilizing feedback controller is designed and the stability region is explicitly characterized. The actuators and sensors of each configuration are connected, via a local communication network, to a local supervisor that orchestrates switching between the constituent configurations, on the basis of the stability regions, in the event of failures. The local supervisors communicate, through a plant-wide communication network, with a plant supervisor responsible for monitoring the different units and coordinating their responses in a way that minimizes the propagation of failure effects. The communication logic is designed to ensure efficient transmission of information between units, while also respecting the inherent limitations in network resources by minimizing unnecessary network usage and accounting explicitly for the effects of possible delays due to fault-detection, control computations, network communication and actuator activation. The proposed approach provides explicit guidelines for managing the various interplays between the coupled tasks of feedback control, fault-tolerance and communication. The efficacy of the proposed approach is demonstrated through chemical process examples. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source] Network positioning and R&D activity: a study of Italian groupsR & D MANAGEMENT, Issue 1 2003Igor Filatotchev Traditionally, R&D studies focus on organisational characteristics and internal context factor effects on a firm's R&D activities. This paper extends previous research by analysing firm,level R&D expenditures in the wider context of inter,organisational networks. Using sample of 2002 manufacturing firms in Italy, it provides evidence that R&D intensity is linked to a firm's positioning within an industrial group's hierarchy. Further tests on the antecedents of R&D expenditures are carried out in relation to the effects of firm characteristics and industry factors. Important findings include a significant and positive association between R&D intensity and the firm's size, performance, intangible assets and industry concentration. These findings suggest that, in addition to firm,level factors and its market environment, network resources and organisation may play an important role in driving the intensity of the firm's R&D expenditures. [source] QoS in IntServ-based IP networks: the peak rate policingEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2003Lorenzo Battaglia In the last few years, IP has moved towards resource reservation, with the task to guarantee in the future Quality of Service (QoS). This has led to flow admission control algorithms based on the negotiation of standardised traffic parameters. QoS can be guaranteed in any network, a priori from the used technology, only if the used admission control algorithm wisely shares the network's resources among the users. Any admission control algorithm on its turn can do so, only if every user respects the negotiated traffic parameters. Since any user could, maliciously or not, send at a higher rate than negotiated, i.e. use a higher share of resources than the negotiated one, in every network in which admission control is performed, a policing algorithm is used. An ideal policer should guarantee to reject no packet of a well-behaved user and police contract violation as rigidly as possible. All this independently of the characteristics of the monitored stream and of the background traffic. This holds also for Integrated Services (IS) based IP networks. In these networks, every user negotiates a peak and an average rate. In this paper we present the solution to the peak rate policing issue. We adapt the Generic Cell Rate Algorithm (GCRA), well-known policer used in ATM networks, to police the peak rate of flows of packets with variable length. We intuitively call this modified GCRA Generic Packet Rate Algorithm (GPRA) and dimension its parameters so that independently of the characteristics of the policed flow and of the background traffic, no packets of a well-behaved user are rejected and that the flows of any misbehaving user are rigidly policed. Copyright © 2003 AEI. [source] | ||||||||||||||||