Shu-Chin Wang

A hybrid load balancing policy underlying grid computing environment

In recent years, network bandwidth and quality has been drastically improved, even much faster than the enhancement of computer performance. The various communication and computing tasks in the fields such as telecommunication, multimedia, information technology, and construction simulation, can be integrated and applied in a distributed computing environment nowadays. However, as the demands of many researches for computing resources gradually grow, Grid Computing integrated with a distributed computing environment and the Internet (network) has gained more attention. The so-called Grid Computing is to utilize the idle computing resources (nodes) on the network to facilitate the execution of complicated tasks that require large-scale computing. In other words, the composition of Grid resources is dynamic and varies with time. Thus, when selecting nodes for executing a task, the dynamic of the nodes in the Grid must be considered, and to exploit the effectiveness of the resources, they have to be properly selected according to the properties of the task. This study proposed a hybrid load balancing policy which integrated static and dynamic load balancing technologies to assist in the selection for effective nodes. In addition, if any selected node can no longer provide resources, it can be promptly identified and replaced with a substitutive node to maintain the execution performance and the load balancing of the system.

Hybrid Intrusion Detection System for enhancing the security of a cluster-based Wireless Sensor Network

Recent advances in Wireless Sensor Networks (WSNs) make them more important to apply. Therefore, security issues are more significant in WSNs. WSNs are susceptible to some types of attacks since they are consisted of cheap and small devices and are deployed in open and unprotected environments. In this research, an Intrusion Detection System (IDS) created in cluster head is proposed. The proposed IDS is a Hybrid Intrusion Detection System (HIDS). It consists of anomaly and misuse detection module. The goal is to raise the detection rate and lower the false positive rate by the advantages of misuse detection and anomaly detection. However, a decision-making module is used to integrate the detect results and to report the types of attacks.

The anatomy study of high performance task scheduling algorithm for Grid computing system

Large-scale computation is frequently limited to the performance of computer hardware or associated cost. However, as the development of information and network technologies thrives, idle computers all over the world can be utilized and organized to enhance overall computation performance; that is, Grid environments that facilitate distributed computation. Hence, the dispatching and scheduling of tasks should be considered as an important issue. Previous studies have demonstrated Grid environments that are composed of idled computers around the globe and are categorized as a type of Heterogeneous Computing (HC). However, scheduling heuristics currently applied to HC focus on the search of minimum makespan, instead of the reduction of cost. In addition, relevant studies usually presume that HC is based on high-speed bandwidth and the communication time is ignored. Further, in response to the call for user-pay policy, as a user dispatches a job to a Grid environment for computation, each execution task would be charged. It is difficult to estimate a job will be dispatched to which and how many computers; it is impossible to predetermine scheduling heuristic which is proposed in previous studies will result in the optimal makespan, and mention actual cost and risk. Therefore, this study proposes ATCS-MCT (Apparent Tardiness Cost Setups-Minimum Completion Time) scheduling algorithm that composes of execution time, weight, due date, and communication time factors to testify that the ATCS-MCT scheduling algorithm not only achieves better makespan than Min-min scheduling heuristics do but also reduces costs.

Grouping Byzantine Agreement

The reliability of the distributed system has always been an important topic of research. Byzantine Agreement (BA) protocol, which allows the fault-free processors to agree on a common value, is one of the most fundamental problems studied in a distributed system. In previous works, the problem was visited in a fully connected network or an unfully connected network with fallible processors. In this paper, the BA problem is reexamined in a group-oriented network, which has the feature of grouping, and the network topology does not have to be fully connected. We also enlarge the fault tolerant capability by allowing dormant faults and malicious faults (also called as the dual failure mode) to exist in a group-oriented network simultaneously. The proposed protocol is more efficient than the traditional BA protocols and can tolerate the maximum number of tolerable faulty processors.

Asynchronous consensus protocol for the unreliable un-fully connected network

In order to achieve reliability in the distributed system, we need a mechanism to enable the system as a whole to continue to function despite the system has some faulty components. The Consensus problem is for the fault-free processors to cope with the faulty components and reach a common value from each other in the distributed system. Traditionally, the Consensus problems were solved in the synchronous network. Subsequently, Chandra and Toueg solved the Consensus problem with crash faulty processor in the asynchronous fully connected network in 1996. In this paper, we will solve the Consensus with dual failure mode (both crash fault and malicious fault) on communication links. The proposed protocol uses the minimum number of rounds of message exchange and can tolerate the maximum number of allowable faulty communication links to make each fault-free processor reach a common consensus value.

Streets of consensus under unknown unreliable network

Generally, tasks in a distributed system, such as two-phase commitment in database system, the location of a replicated file, and a landing task controlled by a flight path finding system, must reach an agreement. This type of unanimity problems is called the agreement problem and one of the most fundamental problems in the field of distributed environment. It requires a set of the processors to agree on a common value even if some components of the system are corrupted. There are many significant studies about these problems in a regularized network environment such as Fully Connected Network, BroadCast Network, and MultiCast Network. Nevertheless, it is computationally infeasible to ignore the network structure in a real environment. In general, the network topology varies with time. Thus, this kind of uncertain network will generate unknown network environment and affect the system to reach a common value. In this paper, the agreement problem will be revisited in an Unknown Network. Simultaneously, Back Propagation Network (BPN) is used to help system to recognize the network structure. Subsequently, the proposed protocol, Unknown Network Protocol (UNP) can reach an agreement that uses the minimum rounds of message exchange and can tolerate the maximum number of faulty components.

Achieving high efficient Byzantine agreement with dual components failure mode on a multicasting network

Under many circumstances, reaching a common agreement in the presence of faulty components is the central issue of fault tolerant distributed computing. So the Byzantine agreement (BA) problem has become more and more important in distributed systems. Traditionally, the BA problem was visited in a fully connected network (FCN), broadcasting network (BCN) and generalized connected network (GCN). Subsequently, malicious fault assumption with processors or communication media was extended to a hybrid fault model on both processors and communication media. However, the network structures (topologies) of FCN, BCN and GCN are not practical. In this study, we lighten restrictions of the network structure to revisit the BA problem with multicasting network (MCN). The proposed protocol uses the minimum number of rounds of message exchange and can tolerate the maximum number of allowable faulty components to make each fault-free processor reach a common agreement in an MCN.

Achieving high efficient agreement with malicious faulty nodes on a cloud computing environment

The reliability of the distributed system has been an important topic of research. Agreement protocols, which allow the correct nodes to agree on a common value, have been brought up to aid the reliable execution of tasks. In previous works, fully connected networks, generalized connected networks or multicastinge components were proposed to solve the agreement problem. Recently, a new concept of distributed computing, cloud computing, is proposed to provide several services. The cloud computing that can make more application for user from the internet. Unfortunately, existing agreement problem and results cannot cope with the new computing environment and the agreement problem thus needs to be revisited. In this paper, a new protocol is proposed to adapt to the cloud computing environment and derive its bound of allowable faulty components.

Reaching fault diagnosis agreement on dual link failure mode

Previously, most Byzantine Agreement protocols could reach an agreement by way of fault masking. Few of them can detect and locate the faulty components. On the other hand, most fault diagnosis algorithms can detect and locate faulty components but few of them can make all fault free processors reach an agreement. The study analyses the messages received at the period of reaching agreement, and then detects and locates the faulty components of the network. Finally, the proposed protocol can further make all fault free processors agree on the common failure report of the synchronous connected network. The symptoms of the faults include the malicious fault and the dormant fault.

Performance enhancement of WiMAX by three layers topology

Worldwide interoperability for Microwave Access (WiMAX) is a telecommunications protocol that provides fixed and mobile internet access. In addition, WiMAX can provide mobile wireless broadband access without the requirement for direct line-of-sight with a base station. In contrast with other wireless networks, WiMAX can provide high broadband speed, large coverage area, multiple bands and support for multimedia. However, a serious problem, the broadcast storm, needs to be addressed due in part to excessive communications from mobile devices, such as file, audio and video sharing. Therefore, a three-layer-based WiMAX network topology is proposed to reduce packet collisions and to enhance performance of communication efficiently. Furthermore, the stability and expansibility of the WiMAX topology can be improved.