Selections of radio access networks by terminals are currently not coordinated and utilizations of the radio resources are not balanced. As a result, radio resources on some radio systems are occupied even though others can afford. In this paper, in order to provide a framework to resolve this issue, Cognitive Wireless Router (CWR) system is proposed for distributed management and independent reconfiguration of heterogeneous wireless networks. The proposed system selects appropriate operational frequency bands and radio systems to connect to the Internet in corporation between the CWRs and a server and therefore can provide optimized wireless Internet access easily even in environments without wired networks. The developed prototype system reconfigures the radio devices to connect to the Internet in 27 seconds at most. It is revealed that this reconfiguration time can be shortened to less than 100 ms by elaborating its procedure. It is also clarified that network data speed required at the server to deal with 10,000 CWRs is only 4.1 Mbps.

In policy-based management, in addition to deliver and enforce policies in managed systems, it is inevitable to manage the policy life-cycle. We mean the policy life-cycle as cyclic iteration of processes involving monitoring to see if the enforced policies actually work at operators' will and their adaptation based on monitoring. Enabling such policy life-cycle management by the current centralized management paradigm such as SNMP may, however, result in poor scalability and reliability. This is typically due to much bandwidth consumption for monitoring and communication failure between a management system and a managed system. It may also impose a heavy burden on the operators in analyzing management information for the policy adaptation. For a solution to that, we propose a scalable and reliable policy-based management scheme enabling the policy life-cycle management based on distributed management paradigm. In the scheme, we provide a new management script describing policies and how their life-cycle should be managed, and execute the script on the managed system with enough computation resources. The scheme can make the current policy-based management more scalable by reducing management traffic, more reliable by distributing management tasks to the managed systems, and more promising by relieving of the operators' burden. We implement a prototype system based on the scheme taking Differentiated Services as a policy enforcement mechanism, and evaluate the scheme from the following viewpoints: 1) the reliability, 2) relievability, and 3) scalability. The first two will be shown with a policy adaptation scenario in an operational network. The last one will be investigated in terms of the management traffic reduction by a management script, the management traffic required for the management of a management script, and the load on a managed system to execute management scripts. As deployment consideration of the proposed scheme besides technical aspects, we also discuss how the prototype system could be integrated with managed systems compliant to the standards emerging in the marketplace.

Distributed configuration management involves maintaining a set of distributed storage and processing resources in such a way that they serve a community of users fairly, promptly, reliably and securely. Security has recently received much attention due to the general anxiety of hacking. Parallel computing systems such as clusters of workstations are no exception to this threat. This paper discusses experiments that measure the effect of employing randomisation in the scheduling of interdependent user and management tasks onto a distributed system such as clusters of workstations. Two attributes are investigated, namely performance and security. Performance is usually the prime objective in task scheduling. In this work the scheduling problem is viewed as a multi-objective optimisation problem where there is a subtle balance between efficient schedules and security. A schedule is secure if it is not vulnerable to malicious acts or inadvertent human errors. Further, the scheduling model should be hidden from unauthorised observers. The results of the study support the use of randomisation in the scheduling of tasks over an insecure network of processing nodes inhabited by malicious users.

The Active HYpermedia Delivery System (AHYDS) facilitates the access to multimedia information over a large-scale network and wide spectrum of media. We developed intelligent access facilities that build on the access paradigms supported by current web applications. This facility generalizes not only different kinds of logical data models (relational, object, hyperlink), but also access mechanisms of multimedia applications to make them customizable and scalable. This paper proposed the distributed management mechanism of the AHYDS platform. The major contribution of this paper is the mechanism for distributed multimedia delivery management over large-scale network and heterogeneous environment. We also propose the mechanism to manage huge multimedia data.

We propose the Geographical Location Information (GLI) system that maps a mobile entity on the Internet to a geographical position. Users can look up the latest geographical location information of registered mobile entities (forward-lookup) and can also search for mobile entities within a specified area (reverse-lookup). The GLI system consists of home and area servers. The home server maintains latest geographical location information of the mobile entities and processes forward-lookup requests. The area server maintains the latest geographical location information of the mobile entities in the area that it manages and processes reverse-lookup requests. To provide a highly scalable system, home and area servers are managed in a distributed manner based on a hierarchical server structure and delegation of authority to servers that manage lower layers. To reduce the amount of traffic due to distributed management, the delegation information of authority is cached by the servers. In our performance evaluation of the GLI system, the prototype implementation can handle 4,500-8,000 requests/sec for location lookup and location registration. We found that 52 home servers and 33 area servers are enough to handle all cars in Japan under some assumed parameters through the performance evaluation.

We have developed a management agent that adapts the delegation concept to achieve efficient network management. In conventional delegation architecture, a network management operator details management operations in an operation-script that describes management operation flow and such network management functions as event management and path tracing. The operator sends this script to agents to execute. In our delegation architecture, the operator sends only a script skeleton describing management operation flow alone; management functions are built into the agents in the form of fuction objects. This helps keep management traffic low. Each function object is designed by utilizing three operational objects: enhanced, primitive, and communication. Each enhanced operational object (EOO) provides a script skeleton with an individual network management function. A primitive operational object (POO) provides an EOO with managed object (MO) access functions. A communication operational object (COO) provides an EOO with a mechanism for accessing the functions of other remote EOOs. We have tested our design by applying it to a path tracing application, and we have measured the total data transfer size between a manager and an agent and the amount of memory usage in our agent's running environment. Evaluation of our implementation suggests that our design can be applied such network management functions as connection establishment and release, fault isolation, and service provisioning.