Network Response Time Research Articles

CIVSched: A Communication-Aware Inter-VM Scheduling Technique for Decreased Network Latency between Co-Located VMs

Server consolidation in cloud computing environments makes it possible for multiple servers or desktops to run on a single physical server for high resource utilization, low cost, and reduced energy consumption. However, the scheduler in the virtual machine monitor (VMM), such as Xen credit scheduler, is agnostic about the communication behavior between the guest operating systems (OS). The aforementioned behavior leads to increased network communication latency in consolidated environments. In particular, the CPU resources management has a critical impact on the network latency between co-located virtual machines (VMs) when there are CPU- and I/O-intensive workloads running simultaneously. This paper presents the design and implementation of a communication-aware inter-VM scheduling (CIVSched) technique that takes into account the communication behavior betweeninter-VMs running on the same virtualization platform. The CIVSched technique inspects the network packets transmitted between local co-resident domains to identify the target VM and process that will receive the packets. Thereafter, the target VM and process are preferentially scheduled by the VMM and the guest OS. The cooperation of these two schedulers makes the network packets to be timely received by the target application. Experimental results on the Xen virtualization platform depict that the CIVSched technique can reduce the average response time of network traffic by approximately 19 percent for the highly consolidated environment, while keeping the inherent fairness of the VMM scheduler.

Grid Computing based on Game Optimization Theory for Networks Scheduling

The resource sharing mechanism is introduced into grid computing algorithm so as to solve complex computational tasks in heterogeneous network-computing problem. However, in the Grid environment, it is required for the available resource from network to reasonably schedule and coordinate, which can get a good workflow and an appropriate network performance and network response time. In order to improve the performance of resource allocation and task scheduling in grid computing method, a game model based on non-cooperation game is proposed. Setting the time and cost of user’s resource allocation can increase the performance of networks, and incentive resource of networks uses an optimization scheduling algorithm, which minimizes the time and cost of resource scheduling. Simulation experiment results show the feasibility and suitability of model. In addition, we can see from the experiment result that model-based genetic algorithm is the best resource scheduling algorithm

Load balancing mechanism for data-centric routing in wireless sensor networks

Routing protocols in wireless sensor networks are became one of the most challenges for these last years. Proposing an efficient and a suitable routing protocol was the aim of many works to route the data with a less consumption of energy and to prolong the network lifetime. This paper investigates a proposition of a new variant of the reference routing protocol Directed Diffusion. This variant, that we call DDLB (Directed Diffusion with Load Balancing mechanism), tries to improve the DD algorithm by introducing a load balancing mechanism in order to balance the energy of the sensors and improve the network lifetime. Simulation results, under the Network Simulator 2 (NS2), show that DDLB can improve the performance more than the standard DD protocol in terms of network lifetime and response time. Further, results show that DDLB can efficiently balance the energy load of the sensors.

A Novel Network Coding and Multi-path Routing Approach for Wireless Sensor Network

In recent times, there have been many advances in the field of information theory and wireless sensor network (WSN) technologies. Network coding is a new paradigm in data transport and promises to change many aspects of WSN. This paper proposes a network coding multipath routing algorithm in WSN (NC-WSN). It is typically proposed in order to increase the reliability of data transmission or to provide load balancing. We evaluate and compare our technique with several existing approaches by a set of simulations, using different scenarios and topologies. The simulations results suggest that the multipath diversity achieved with our proposition can significantly improve the network response time.

Enhancing Teaching and Learning Wi-Fi Networking using Limited Resources to Undergraduates

Motivating students to learn Wi-Fi (wireless fidelity) wireless networking to undergraduate students is often difficult because many students find the subject rather technical and abstract when presented in traditional lecture format. This paper focuses on the teaching and learning aspects of Wi-Fi networking using limited hardware resources. It provides a walk-through tutorial on setting up Wi-Fi networks using wireless laptops and access points. Students can easily set up and configure Wi-Fi networks using relatively few computing resources to learn networking concepts more effectively. By measuring the key performance metrics such as network throughput and response times, students are able to gain a deeper understanding of Wi-Fi network performance and related issues. The effectiveness of these Wi-Fi practical learning activities has been evaluated both formally by students and informally in discussion within the teaching team. This paper describes the overall effectiveness of teaching and learning Wi-Fi network fundamentals using limited resources.

A Computing Capability Allocation Algorithm for Cloud Computing Environment

For several special features in the environment of cloud computing, which may be quite different from the centralized computing infrastructure currently available, the existed method of resource allocation used in the grid computing environment may not be suitable for these changes. In our paper, a new allocation algorithm based on Ant Colony Optimization (ACO) is proposed to satisfy the needs of Infrastructure as a Service (IaaS) supported by the cloud computing environment. When started, this algorithm first predicts the capability of the potentially available resource nodes; then, it analyzes some factors such as network qualities and response times to acquire a set of optimal compute nodes; finally, the tasks would be allocated to these suitable nodes. This algorithm has shorter response time and better performance than some of other algorithms which are based on Grid environment when running in the simulate cloud environment. This result is verified by the simulation in the Gridsim environment elaborated in the following section.

A lightweight framework for prediction-based resource management in future wireless networks

The vast proliferation and widespread use of a variety of mobile devices in the heterogeneous networking environment necessitates the introduction of lightweight management mechanisms to ease the administration complexity and optimise the overall system performance. To this end, one key research problem is the design of novel functionalities in network nodes to enable their self-adaptation to varying operational conditions, e.g. their own resources saturation--and to the status of other neighbouring nodes, to assure stability and optimality in the resource management. In these terms, the introduction of advanced techniques for the load balancing of users' requests in order to avoid the resources saturation is a fundamental objective. The latter addresses both the local node level as well as the cluster level of neighbouring nodes. In this article, an appropriate model for the management of computational system resources is proposed, enhanced with prediction schemes. An algorithmic framework is introduced for the proactive load balancing of user decision-making requests, assuming reconfigurable and autonomous mobile devices. The latter is based on the proposed metric of user satisfaction; such metric is a function of the network response time for serving the decision-making requests. An analytical model has been proposed to compute the predicted values of the user satisfaction, extending the prediction models by Andreolini. Acting on top of the typical load-balancing actions for handling the current resources saturations, the goal of this framework is to avoid the full utilisation of system resources in the near future. Afterwards, the introduced prediction-based load-balancing framework has initially been evaluated in a test-single node system and then applied in a case study system. The obtained results show the gains of the presented framework in terms of the number of dropped user requests. The introduction of prediction schemes enables to minimise the number of dropped user requests for both classes of mobile devices. It should be noted that the prediction framework optimises the failure rates for the autonomous mobile devices. This outcome indicates that the introduction of intelligence in the mobile devices eases their proactive management.

Signalling by protein phosphatases and drug development: a systems‐centred view

Protein modification cycles catalysed by opposing enzymes, such as kinases and phosphatases, form the backbone of signalling networks. Although, historically, kinases have been at the research forefront, a systems-centred approach reveals predominant roles for phosphatases in controlling the network response times and spatio-temporal profiles of signalling activities. Emerging evidence suggests that phosphatase kinetics are critical for network function and cell-fate decisions. Protein phosphatases operate as both immediate and delayed regulators of signal transduction, capable of attenuating or amplifying signalling. This versatility of phosphatase action emphasizes the need for systems biology approaches to understand cellular signalling networks and predict the cellular outcomes of combinatorial drug interventions.

The Research and Simulation of CSMA/CA Mechanism of ZigBee Protocol

In order to improve the performance of star-topology ZigBee network with fewer nodes, modified the CSMA/CA channel access mechanism of ZigBee protocol, and proposed an improved channel access mechanism - Circular Queue access mechanism. Described and realized Circular Queue mechanism; showed the beacon frame format of Circular-Queued. Finally, gave the simulation results, compared and analyzed the network performance of CSMA / CA mechanism before and after the modification from network response time, throughput, packet loss rate.

A study for the reduction of network traffic through an efficient processing of the trend analysis information

Network traffic demand is increasing explosively because of various smart equipment and services on smart era. It causes of traffic overload for wireless and wired network. Network management system is very important to control the explosion of data traffic. It uses SNMP to communicate with various network resources for management functions and creates lots of management traffic. Those are can be serious traffic congestion on a network. I propose an improving function of SNMP to minimize unnecessary traffics between manager and agent for collecting the Trend Analysis Information which is mainly used to monitor and accumulate for a specific time period in this paper. The results of test show it has compatibility with the existing SNMP and greatly decreases the amount of network traffic and response time.

정보센터 시스템 품질이 클라우드 서비스 이용의도에 미치는 영향 연구

본 연구는 고도화된 웹 서비스와 스마트 기기의 확산으로 인해 변화된 시스템 환경 속에서 클라우드 서비스에 대한 선호도와 이용의도에 영향을 미치는 데이터 안정성, 네트워크 반응속도, 그리고 시스템 접근성을 중심으로 정보센터의 이용도 향상에 대한 방향 설정을 위해 인지된 유용성, 인지된 이용 용이성을 중심으로 이용자의 이용의도와의 관계를 살펴보았다. 본 연구가설의 검증을 위해 태블릿PC, 스마트폰과 같은 모바일기기를 많이 이용하거나 관심이 높은 20대에서 30대 연령층의 114명으로 부터 설문을 받아 활용하였다. 클라우드 서비스 선호도에 대한 이용자의 인지된 유용성과 인지된 이용용이성에 영향을 미칠 수 있는 정보센터의 시스템 품질특성과 관련된 요인들과의 관계를 살펴봄으로써 최근의 클라우드 서비스를 위해 새롭게 고려되어야 할 정보센터의 시스템 품질특성에 대해 이용자 이용의도 관점에서 논의하였다.

Design and performance test of spacecraft test and operation software

Main test processor (MTP) software is the key element of Electrical Ground Support Equipment (EGSE) for spacecraft test and operation used in the Chinese Academy of Space Technology (CAST) for years without innovation. With the increasing demand for a more efficient and agile MTP software, the new MTP software was developed. It adopts layered and plug-in based software architecture, whose core runtime server provides message queue management, share memory management and process management services and forms the framework for a configurable and open architecture system. To investigate the MTP software's performance, the test case of network response time, test sequence management capability and data-processing capability was introduced in detail. Test results show that the MTP software is common and has higher performance than the legacy one.

A Parametric Colored Petri Net Model of a Switched Network

A parametric Colored Petri net model of the switched Ethernet network with the tree-like topology is developed. The model’s structure is the same for any given network and contains fixed number of nodes. The tree-like topology of a definite network is given as the marking of dedicated places. The model represents a network containing workstations, servers, switches, and provides the evaluation of the network response time. Besides topology, the parameters of the model are performances of hardware and software used within the network. Performance evaluation for the network of the railway dispatcher center is implemented. Topics of the steady-stable condition and the optimal choice of hardware are discussed.

A DYNAMIC LOAD BALANCING MODEL FOR CONCURRENTLY CONNECTED USERS IN U-HEALTHCARE MONITORING SYSTEMS

U-healthcare systems are based on a ubiquitous and wireless computing and communication environment. They are comprised of the U-healthcare management center, electronic medical records (EMR) system, and the associated services for users and patients. The U-healthcare management center performs continuous monitoring and provides support services in multiple areas, requiring careful allocation of the limited service resources to provide customized healthcare services for users of the mobile distributed system. When the number of locally connected users increases rapidly, a mobile allocation and distribution server can be imbalanced by the load on service resources, resulting in delayed services. This study proposes a dynamic load balancing model for reducing the load of users on service resources and supporting efficient response services in a mobile distributed system. The proposed dynamic load balancing model clusters the system resources of servers dynamically, according to each users' movement and time. The dynamic clustering of system resources uses wFCM (weighted Fuzzy C-Means), which changes the cluster center by transforming existing FCM (Fuzzy C-Means) from a fixed weight to a dynamic one. Using wFCM, the load balance can be maintained, based on the usage rate of service resources, such as CPU, memory, and network. In addition, the balance between QoS (Quality of Service) requests and network response times can be maintained by adding an abstraction layer between application services and network infrastructure. Therefore, when the proposed model is applied to a U-healthcare monitoring system, the system can perform near real-time monitoring of service users in the mobile distributed environment, and effectively address emergent situations. This study evaluates the response time of the implemented model in relation to the number of concurrently connected users, and confirms that the proposed model is faster in response and service processing than existing WLC (Weighted Least-Connection Scheduling) and FCM (Fuzzy C-Means).

Improving web cache server performance through arbitral thread and delayed caching

As the number of Internet users increase explosively, the delay in network response time is also increasing. An economic and efficient solution for this problem is web caching. But the use of a cache server can cause another bottleneck because of the concentration of requests at the cache server. Many studies on improving cache server performance have been suggested, but existing studies have focused on load balancing and/or caching capacity, not directly on improving the throughput of a single cache server. In this paper, we analyze the causes of cache server bottleneck, and propose an arbitral thread and the delayed caching mechanism as a solution. We use an arbitral thread in order to provide a quick service to users' service requests, and we use delayed caching in order to improve system reliability. The proposed cache server is implemented through a modification of the SQUID cache server, and we compare its performance with the original SQUID cache server.

A new congestion control algorithm for improving the performance of a broadcast-based multiprocessor architecture

Congestion occurring in the input queues of broadcast-based multiprocessor architectures can severely limit their overall performance. The existing congestion control algorithms estimate congestion based on a node’s output channel parameters such as the number of free virtual channels or the number of packets waiting at the channel queue. In this paper, we have proposed a new congestion control algorithm to prevent congestion on broadcast-based multiprocessor architectures with multiple input queues. Our algorithm performs congestion control at the packet level and takes into account the next input queue number which will be accessed by the processor, which form the fundamental differences between our algorithm and the algorithms based on the idea of virtual channel congestion control. The performance of the algorithm is evaluated by OPNET Modeler with various synthetic traffic patterns on a 64-node Simultaneous Optical Multiprocessor Exchange Bus (SOME-Bus) architecture employing the message passing protocol. Performance measures such as average input waiting time, average network response time and average processor utilization have been collected before and after applying the algorithm. The results show that the proposed algorithm is able to decrease the average input waiting time by 13.99% to 20.39%, average network response time by 8.76% to 20.36% and increase average processor utilization by 1.92% to 6.63%. The performance of the algorithm is compared with that of the other congestion control algorithms and it is observed that our algorithm performs better under all traffic patterns. Also, theoretical analysis of the proposed method is carried out by using queuing networks.

Modeling and Performance Evaluation of Reconfiguration Decision Making in Heterogeneous Radio Network Environments

In heterogeneous radio network environments, the incorporation of dynamic adaptation capabilities in the protocol stack of mobile devices is an important challenge. In this direction, an appropriate model of the network decision-making process for mobile device adaptation is presented. Two main adaptation alternatives are assumed: (1) handover and (2) protocol reconfiguration. We consider two classes of mobile devices, i.e., reconfigurable and autonomous; the difference between them lies on the degree by which they support the decision-making functionality. An algorithmic framework for the management of the decision-making requests for reconfiguration or handovers is proposed. This work is based on the introduced metric of user satisfaction, which is based on the network response time for serving the decision-making requests. Such a framework is important for guiding the relocation of mobile terminals to achieve offloading. Furthermore, an analytical model for the computation of the user satisfaction is introduced, based on the work by Litoiu The analysis uses multiclass queuing networks to model the requests to the network as transactions among the system entities and compute the user satisfaction and the required parameters, e.g., network response time bounds. The obtained results show how the global bounds on the asymptotic network response time and throughput per class are affected by the number and frequency of reconfiguration decision requests. The analysis quantifies how the increase in the autonomicity level of mobile devices affects the network load and how to maximize the percentage of requests handled by the network, compared with the percentage of dropped requests. Moreover, our work reveals the degree of performance deterioration caused by increasing the autonomicity level in the management of requests.

The Design and Implementation of Bus LAN Simulation System Based on Object-Oriented Technology

Computer simulation is one of methods used in evaluating the performance of LAN. In order to decrease network response time, the simulation system of P-persistent CSMA/CD Bus LAN is designed and implemented using Visual C++, by using the object-oriented analysis. Finally, the effect of the send probability for the network performance has been analyzed.

OMA DM‐based remote software fault management for mobile devices

AbstractMobile devices (e.g. mobile handsets or PDAs) have gained much functionality and intelligence with the growth of mobile network technologies and the increased use of mobile services. As a consequence, mobile devices have become more complex and many related problems have occurred. Specifically, sudden rebooting and freezing problems caused by software faults decrease the availability of the mobile device and cause inconvenience to end‐users. To solve such problems, academia and industry have focused on Open Mobile Alliance (OMA) Device Management (DM); this method is the international de facto standard for mobile device management. In this paper, we propose a software fault management method to remotely determine and correct problems of mobile devices based on OMA DM. We present a definition of management objects and a method to collect them from mobile devices using the OMA DM protocol. We also present a method for debugging and correcting software faults using the collected information. Finally, we present a prototype implementation and performance evaluation to validate our proposed method. Results of the performance evaluation show that our proposed method is efficient and scalable in regard to network traffic overhead and response time. Copyright © 2009 John Wiley & Sons, Ltd.

Opportunities and Limits of Remote Timing Attacks

Many algorithms can take a variable amount of time to complete depending on the data being processed. These timing differences can sometimes disclose confidential information. Indeed, researchers have been able to reconstruct an RSA private key purely by querying an SSL Web server and timing the results. Our work analyzes the limits of attacks based on accurately measuring network response times and jitter over a local network and across the Internet. We present the design of filters to significantly reduce the effects of jitter, allowing an attacker to measure events with 15-100 μ s accuracy across the Internet, and as good as 100ns over a local network. Notably, security-related algorithms on Web servers and other network servers need to be carefully engineered to avoid timing channel leaks at the accuracy demonstrated in this article.