Diagnosing interoperability problems and debugging models by enhancing constraint satisfaction with case -based reasoning

Modeling, Diagnosis, and Model Debugging are the three main areas presented in this dissertation to automate the process of Interoperability Testing of networking protocols. The dissertation proposes a framework that uses the Constraint Satisfaction Problem (CSP) paradigm to define a modeling language and problem solving mechanism for interoperability testing, and uses Case-Based Reasoning (CBR) for debugging interoperability test cases. The dissertation makes three primary contributions: (1) Definition of a new modeling language using CSP and Object-Oriented Programming. This language is simple, declarative, and transparent. It provides a tool for testers to implement models of interoperability test cases. The dissertation introduces the notions of metavariables, metavalues and optional metavariables to improve the modeling language capabilities. It proposes modeling of test cases from test suite specifications that are usually used in interoperability testing performed manually by testers. Test suite specifications are written by organizations or individuals and break down the testing into modules of test cases that make diagnosis of problems more meaningful to testers. (2) Diagnosis of interoperability problems using search supplemented by consistency inference methods in a CSP context to support explanations of the problem solving behavior. These methods are adapted to the OO-based CSP context. Testers can then generate reports for individual test cases and for test groups from a test suite specification. (3) Detection and debugging of incompleteness and incorrectness in CSP models of interoperability test cases. This is done through the integration of two modes of reasoning, namely CBR and CSP. CBR manages cases that store information about updating models as well as cases that are related to interoperability problems where diagnosis fails to generate a useful explanation. For the latter cases, CBR recalls previous similar useful explanations

Application of Asynchronous Transfer Mode (Atm) technology to Picture Archiving and Communication Systems (Pacs): A survey

Broadband Integrated Services Digital Network (R-ISDN) provides a range of narrowband and broad-band services for voice, video, and multimedia. Asynchronous Transfer Mode (ATM) has been selected by the standards bodies as the transfer mode for implementing B-ISDN; The ability to digitize images has lead to the prospect of reducing the physical space requirements, material costs, and manual labor of traditional film handling tasks in hospitals. The system which handles the acquisition, storage, and transmission of medical images is called a Picture Archiving and Communication System (PACS). The transmission system will directly impact the speed of image transfer. Today the most common transmission means used by acquisition and display station products is Ethernet. However, when considering network media, it is important to consider what the long term needs will be. Although ATM is a new standard, it is showing signs of becoming the next logical step to meet the needs of high speed networks; This thesis is a survey on ATM, and PACS. All the concepts involved in developing a PACS are presented in an orderly manner. It presents the recent developments in ATM, its applicability to PACS and the issues to be resolved for realising an ATM-based complete PACS. This work will be useful in providing the latest information, for any future research on ATM-based networks, and PACS

Scalable QoS routing in MPLS networks using mobile code

In a continually evolving Internet, tools such as Q u a lity o f Service ro u tin g must be used in order to accommodate user demands. However, deploying and developing QoS routing in the legacy Internet is difficult. Multiprotocol Label Switching (MPLS) facilitates the deployment of QoS routing, due to its separation of functions between the control and forwarding plane. Developing QoS routing raises scalability issues within very large networks. I propose overcoming these issues by using topology aggregation and distributed routing based on modem techniques such as active networks and mobile agents. However, topology aggregation introduces inaccuracy, which has a negative impact on QoS routing performance. To avoid such problems I propose a hierarchical routing protocol, called Macro-routing, which by using distributed route computation is able to process more detailed information and thus to use the most accurate aggregation technique, i.e. Full-Mesh. Therefore, the protocol is more likely to find the best path between source and destination, and can also find more than one available path. QoS routing, which is used for finding feasible paths that simultaneously satisfy multiple constraints, is also called multiple-constrained routing and is an NP-complete problem. The difficulty of solving such problems increases in a hierarchical context, where aggregation techniques influence the path computation process. I propose a new aggregation technique which allows the selection of multiple paths that satisfy multiple QoS constraints. This reduces the probability of a false negative, i.e., of the routing algorithm incorrectly reporting that no path satisfying the constraints exists. This aggregation technique is called extended full-mesh (EFM) and is intended for use with the Macro-routing protocol. Deploying these protocols in the Internet will allow multi-constrained routing to be practically implemented on large networks