Paul Baran, Network Theory, and the Past, Present, and Future of Internet

Paul Baran’s seminal 1964 article “On Distributed Communications Networks” that first proposed packet switching also advanced an underappreciated vision of network architecture: a lattice-like, distributed network, in which each node of the Internet would be homogeneous and equal in status to all other nodes. Scholars who have subsequently embraced the concept of a lattice-like network approach have largely overlooked the extent to which it is both inconsistent with network theory (associated with the work of Duncan Watts and Albert-László Barabási), which emphasizes the importance of short cuts and hubs in enabling networks to scale, and the actual way, the Internet initially deployed, which relied on a three-tiered, hierarchical architecture that was actually what Baran called a decentralized network. However, empirical studies reveal that the Internet’s architecture is changing: it is in the process of becoming flatter and less hierarchical, as large content providers build extensive wide area networks and undersea cables to connect directly to last-mile networks. This change is making the network more centralized rather than becoming more distributed. As a result, this article suggests that the standard reference model that places backbones at the center of the architecture should be replaced with a radically different vision: a stack of centralized star networks, each centered on one of the leading content providers

Die Geschichte des Internet als Lernprozess

"Der Beitrag reflektiert die bisherigen Geschichtsbetrachtungen von Pionieren und Historikern des Internet. Er möchte zeigen, dass die bislang dominierende heroische Sichtweise die eigentlich interessierenden Entwicklungen des Internets von einer unvollständigen Systemlösung zu einem massentauglichen Informations- und Kommunikationsmedium ausblendet. Am Beispiel des Wandels der Leitbilder und Nutzungsszenarien der engeren Internet-Community und der Prägungswirkungen der Akteurskonstellationen auf die Netzwerkarchitektur werden neuere Ansätze der historischen Technikgeneseforschung auf die Internet-Entwicklung angewendet. Dabei zeigt sich, dass das heutige Internet keinesfalls von Beginn an so geplant war und dass sein Erfolg immer wieder durch akteurbedingte Schließungsprozesse gefährdet war. Die stufenweise Ausweitung der Nutzerpopulationen und die Entstehung und Verkettung kritischer Massen waren vielmehr Resultat vielfältiger Lernprozesse sowie sozio-technischer und ergonomischer Innovationen, die vor allem durch kritische User eingebracht wurden." (Autorenreferat

Militärische Einflüsse auf Leitbilder, Lösungsmuster und Entwicklungsrichtungen der Computerkommunikation: Vortrag auf der Technikgeschichtlichen Jahrestagung des VDI, 5./6.März 1992 "Militärische und zivile Technik; Wechselwirkungen in historischer Perspektive

Während die Spin-off-Forschung bisher überwiegend Apparate- oder Bauelementetechniken untersucht hat, möchte der folgende Beitrag anhand der Computerkommunikation komplexere Anwendungssysteme unter dem Aspekt des militärisch-zivilen Technologietransfers analysieren. Der Begriff der Computerkommunikation umfaßt dabei sowohl Entwicklung, Betrieb und Nutzung von Daten- und Rechnernetzen als auch die entsprechenden Infrastruktur-Einrichtungen, und zwar von der lediglich fernmeldetechnischen Verbindung von Computern, Terminals usw. bis zu integrierten Computernetzen, die über den reinen Datentransport hinaus auch den Ressourcen-, Last- und Funktionsverbund realisieren können. Da wesentliche Basis- und Systemtechniken sowie die frühen Anwendungskonzepte vor allem im militärindustriellen Komplex der USA entstanden sind, steht die US-Entwicklung der Computerkommunikation hier im Mittelpunkt. Anhand der beiden wichtigsten militärischen Großvernetzungsprojekte, SAGE und ARPANET, werden verschiedenartige Prägungsformen mit unterschiedlicher Prägungstiefe untersucht. Dabei zeigt sich, daß immaterielle Übertragungsvorgänge wie der Leitbildtransfer und eine generelle (Fehl-)Orientierung des Problemlösungshorizontes von Ingenieuren eine viel folgenreichere Bedeutung haben können als die bisher von der Spin-off-Forschung bisher analysierten unmittelbaren kommerziellen Einflüsse auf Hard- und Software-Techniken.Until now the attention of most research studies on spin-off has concentrated on special apparatus and component technologies or on macroeconomic balances. In contrast to them the following article on the military genesis of computer communication networks tries to examine more complex qualitative impacts of military-civilian technology transfer. Focussing on the two most important U.S. computer networking projects, SAGE and ARPANET, different kinds and intensities of impacts on components, system architectures, and application concepts are analysed, resulting in the thesis, that negative effects on the technological and economic development in consequence of the transfer of inadequate military visions (Leitbilder) into civilian environments and general misorientations of the problem solving horizon probably exceed the identified sectoral commercial profits of spin off

The integrity of serial data highway systems

The Admiralty Surface Weapons Establishment (ASWE) have developed a Local Area Network System. This thesis describes the development of a replacement for this LAN system, based around 16 bit microprocessor hosts, as opposed to the minicomputers currently used. This change gave a substantial reduction in size, and allowed the new system to be installed on a ship and tested under operational conditions. Analysis of the data collected during the tests gave performance information on the ASWE system. The performance of this LAN is compared to that of other leading types of LAN. The design of a portable network controller/ monitor unit is presented, which may be manufactured as a standard controller for the ASWE Serial Highway

A system for the simulation of hardware to software allocation and performance evaluation

Imperial Users onl

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

OPTIMISATION TECHNIQUES FOR TELECOMMUNICATION NETWORKS

This thesis deals with various facets of the optimisation problem for telecommunication networks and proposes a number of new techniques for their solution. The necessary essentials, Graph Theory, Complexity Theory and Telecommunication Principles, are investigated. The relevant graphs are enumerated and the requirements of suitable optimisation algorithms for certain graphical problems are established. The Private Automatic Branch Exchange (PABX) is introduced. the variety of telecommunications traffic as well as the practical requirements of a connection topology are discussed. The fundamental Network Optimisation Problem (NJP) is defined and analysed. Simple exhaustive methods of solution are considered together with partial solution algorithms and simplification methods. Centralised networks with and without concentrators are introduced. Extensions and modifications are proposed for some techniques and existing practical methods of dealing with the NOP are investigated. A number of new ideas are proposed for the practical solution of the NOP. Reduction methods are presented for replacing large unmanageable networks with smaller ones, on which optimisation can take place. Fixed topology techniques are introduced for initial tandem switch selection purposes and perturbation methods are considered which can be applied to such an initial solution. Lookahead methods of link removal are introduced for the purposes of determining the tandem interconnection network together with the traffic routeing strategy. A composite method is proposed incorporating all of these concepts and the results of a number of numerical experiments upon actual network problem; are presented. the extension of the proposed techniques to other areas of problem solving and optimisation is considered. In particular, a new method for the solution of the Euclidean Travelling Salesman Problem (ETSP) is presented. A brief discussion is undertaken, in conclusion, concerning the practical difficulties of the NOP and The restrictions this placed upon solution algorithms of various types.Brit1sh Telecom, Ta1lis Consultancy, Londo

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