Libing Wu

A linked-list data structure for advance reservation admission control

With the development of multimedia and grid technologies, more and more distributed applications require guaranteed quality of service and maintain minimum network resource during their running sessions. Thus advance reservation is necessary because it provides a solution for the need of reserving network resources for future use. Many kinds of data structures were proposed to perform fast and efficient admission control. Most of them are based on the time-slotted method, which needs to make an appropriate tradeoff between the efficiency and the granularity of the time slots. In this paper, a linked-list data structure is proposed to perform the admission control for advance reservation. Compared with the existing bandwidth tree and time-slotted array, the proposed linked list shows better performance.

Flexible Advance Reservation for Grid Computing

Requests of advance reservation with fixed parameters, i.e. start time, end time and resource capability, may be rejected due to instantaneous peaks of resource utilization. Gaps between these peaks are too narrow for additional requests to fit in. As a result, the call acceptance rate of reservation would decrease dramatically, and the performance of resource may be reduced. In fact, many resource reservations for grid applications don’t need fixed parameters. In this paper, a flexible advance reservation is introduced. Its parameters can be modified according to resource status in order to fill the gaps of resource. Particular admission control algorithm for this new type of reservation is provided too. Simulation shows that it can improve performance of resource reservation in terms of both call acceptance rate and resource utilization.

An Adaptive Advance Reservation Mechanism for Grid Computing

Reservation in advance provides a solution for the need of reserving the network resource for future. Advance reservation for global grids becomes an important research area as it allows users to gain concurrent access for their applications to be executed in parallel, and guarantees the availability of resources at specified future times. But performance of reservation for grid was seldom considered. In this paper, an adaptive advance reservation is introduced. It can modify not only the parameters of latest request but also that of admitted requests because sometimes the latest request is fixed with parameters. Particular admission control algorithm for this new type of reservation is provided too. Simulation shows that it can improve performance of resource reservation in terms of both call acceptance rate and resource utilization when the percentage of fixed requests is not very high.

Research on an Effective Mechanism of Task-scheduling in Grid Environment

This paper gives a definition of the communication overhead among nodes in task scheduling and resource management in grid environment, presents rules of building QoS routing tree based on the QoS routing algorithm, proposes grid heap-sort algorithm and QoS routing algorithm, and designs a scheme of grid task scheduling with the help of them. The results of its correlative experiment indicate that this design can guarantee quality of service in grid better

A Novel Interoperable Model of Distributed UDDI

UDDI acts a very important role in the web service. It can be used to publish and lookup services. Most of the current UDDI models are centralized so that the performance will decrease if there are too many services to be registered or queried. In this paper, an interoperable model of distributed UDDI is proposed. The model divides whole UDDI servers into there types: root server, super domain server and normal server. The simulation results show that the model can get better lookup performance.

The Research and Implementation of ARP Monitoring and Protection

The flaws of ARP protocol, the kinds of ARP attack and the major existing defensive technologies are analyzed in details. Due to the cost of existing defensive technologies is too high; therefore, we design and develop a light-weight tool based on Linux platform. It is suitable for most users because it can detect and defend the ARP attacks accompany with very small extra overhead. Moreover, it is convenient for administrators to manage network. Detailed design and some key codes are presented in this article.

More Efficient Mechanism of Topology-Aware Overlay Construction in Application-Layer Multicast

Application-layer multicast (ALM) can easily address most of the problems of IP-based multicast such as forwarding state scalability, full router dependence and so on. The topology-aware approach of ALM is more attractive because it exploits underlying network topology data to construct multicast overlay networks. In this paper, a more efficient mechanism of overlay construction called subnet topology-aware grouping (STAG) is introduced. Under this mechanism, new node who wants to join the multicast tree will broadcast a JOIN message in the subnet firstly or at the same time when it sends a JOIN message to source member. It can save the time used to discover topology information and execute the path matching algorithm if there are some multicast members in the same subnet. Simulation results show that new nodes of STAG can acquire multicast service more quickly with similar or less overhead when the group size is large or the percentage of subnet nodes is high.

Ant colony optimization for PON network design

Optical access technology has quickly got a worldwide development. Currently, the deployment of equipment and fiber lines in the optical access network require complex manual design. However, because of non-standard artificial design, it is difficult to make the network reasonable, and increasing post-engineering and maintenance difficulties. Based on the partition algorithm in the previous article, this paper presents a new partitioning algorithm for the PON network design, which is a combination of the Ant Colony Optimization algorithm and partitioning algorithm. Compared with other algorithms, the ant colony optimization is more efficient and more accurate. It is very suitable for solving calculating the capacity of the large and complex network. Therefore, we use ant colony optimization for PON network design. By entering the number of nodes, users, service traffic, the unit cost parameters, it can automatically calculate the number and configuration of OLT, which can help to optimize the network layout, and save the network construction costs.

A Study of Improving Apriori Algorithm

The Apriori algorithm is one of the most influential apriori for mining association rules. The basic idea of the Apriori algorithm is to identify all the frequent sets. Through the frequent sets, derived association rules, these rules must satisfy minimum support threshold and minimum confidence threshold. This paper presents improved algorithms, mainly through the introduction of interest items, frequency threshold, to improve the mining efficiency, dynamic data mining to facilitate the needs of users. Confirmed by many experiments, this algorithm is better than traditional algorithms in time and space complexity.

A Connectivity-Prior Model for Generating Connected Power Law Random Graphs with Prescribed Degree Sequence

Generating precise network topologies is an important issue for the purpose of simulating and evaluating networking applications. Recent research results reveal that the topology of Internet is neither a purely random network nor a hierarchical structure, but similar to complex networks obeying power law distributions. Under this condition, a practical degree-driven method is widely used for generating network topologies with prescribed degree sequence. To import random features, additional random transformations are required to perform upon the generated graph. In this paper, we propose a connectivity-prior algorithm to create a connected graph and develop a simple but efficient method to perform randomization operations to transform the generated graph. During the creating and transforming process, the graph is kept connected. We made experiments with the latest degree sequence data of the actually Internet topologies. The results show that our method works more efficiently.