COMPUTER NETWORK ANALYSIS AND OPTIMISATION

This thesis presents a study and analysis of the major influences on network cost and their related performance. New methods have been devised to find solutions to network optimisation problems particular to the AT&T ISTEL networks in Europe and these are presented together with examples of their successful commercial application. Network performance is seen by the user in terms of network availability and traffic delay times. The network performance is influenced by many parameters, the dominating influences typically being the number of users accessing the network, the type of traffic demands they place upon it and the particular network configuration itself. The number of possible network configurations available to a network designer is vast if the full range of currently available equipment is taken into account. The aim of this research has been to assist in the selection of most suitable network designs for optimum performance and cost. This thesis looks at the current differing network technologies, their performance characteristics and the issues pertinent to any network design and optimisation procedures. A distinction is made between the network equipment providing user 'access' and that which constitutes the cross country, or *core\ data transport medium. This partitioning of the problem is exploited with the analysis concentrating on each section separately. The access side of the AT&T ISTEL - UK network is used as a basis for an analysis of the general access network. The aim is to allow network providers to analyse the root cause of excessive delay problems and find where small adjustments to access configurations might lead to real performance improvements from a user point of view. A method is developed to allow statistical estimates of performance and quality of service for typical access network configurations. From this a general method for the optimisation of cost expenditure and performance improvement is proposed. The optimisation of both circuit switched and packet switched computer networks is shown to be difficult and is normally tackled by the use of complex procedures on mainframe computers. The new work carried out in this study takes a fresh look at the basic properties of networks in order to develop a new heuristic method for the design and optimisation of circuit switched core networks on a personal computer platform. A fully functional design system was developed that implements time division multiplexed core network design. The system uses both a new heuristic method for improving the quality of the designs and a new 'speed up' algorithm for reducing times to find feasible routes, thereby dramatically improving overall design times. The completed system has since been used extensively to assist in the design of commercial networks across Europe.AT&T ISTEL Ltd., Redditch, Englan

Paketverarbeitende Systeme – Algorithmen und Architekturen für hohe Verarbeitungsgeschwindigkeiten

Paketverarbeitende Systeme basieren auf zwei wichtigen Bereichen: der eigentlichen Paketverarbeitung und der Paketklassifizierung. Zur Optimierung der Paketverarbeitung wurde eine FPGA-basierte Architektur für funktionale Module entwickelt, auf deren Basis verschiedene Funktionen für den Einsatz im Teilnehmerzugangsnetzwerk realisiert wurden. Hash-basierte Klassifizierungsalgorithmen und –architekturen sind grundsätzlich für die Paketklassifizierung geeignet. Zur Optimierung dieser Klasse von Algorithmen wurde eine evolvierbare Hashfunktionsarchitektur entwickelt.Packet processing systems base on two important areas: ultimate packet and packet classification. For optimization of packet processing an FPGA-based architecture for functional modules has been developed. For application in Access Network, different functional modules have been developed. Hash-based classification algorithms and architectures are appropriate for fast packet classification. For optimization of this class of algorithms, an evolvable architecture for hash functions has been developed

Proceedings of a IIASA Conference on Computer Communications Networks

This publication contains the papers presented at the Conference on Computer Networks organized by the Computer Science Project of IIASA in October 1974. This area is one of the main concerns of the Computer Science Project, but also has a broader significance for the Institute. IIASA deals with various problems of industrialization and its consequences, and inevitably depends on permanent working contacts with a number of national institutions. The interdisciplinary and international character of the Institute is essential to success in finding solutions to these problems. Applied research today depends heavily on the use of large amounts of data and data processing. We believe that connecting computers installed in various national institutions will contribute significantly to the achievements of the main goals, allowing for the exchange of data and programs, and in this way facilitating the understanding of problems, resulting in faster solutions. This Conference was the first of a series of conferences and workshops to be held on this topic. In addition to the exchange of ideas and the discussion of problems arising in networking, it was intended also to identify people and institutions that were interested in establishing links contributing to the achievement of the goals of the Institute. In addition to the presentation of papers and formal discussions, discussions on the periphery of the conference were probably of equal importance. The papers presented do not reflect the spirit of cooperation which was very characteristic of the conference. However, we feel that the publication of these papers will be useful to the scientific community and give a picture of recent developments in this area. Mr. J. Sexton and Miss U. Sichra are staff members of the Computer Science Project who devoted a great deal of their time and efforts to the editing of the papers. Mrs. H. MacKinnon was especially helpful in the technical editing and polishing of a number of the papers presented