Showing papers on "Cognitive network published in 1983"

An Interference Analysis of Interconnection Networks.

Abstract: An interference analysis of the interconnection networks (INS) for a tightly coupled multiprocessor is presented. The interconnections considered are crossbars and delta networks. Two situations are examined: when a memory module is equally likely to be addressed by a processor and when a processor has a favorite memory. It is shown that for a higher rate of favorite requests, the delta networks perform close to a crossbar. 15 references.

A distributed approach to the interconnection of heterogeneous computer networks

Abstract: This paper describes a distributed architecture for the flexible interconnection of heterogeneous networks with a number of mini- and micro computers, in a research environment. The interconnected networks include the DARPA Internet, which uses the DoD protocols, and the X25-based networks PSS and SERCNET. The approach described here distributes the network access into a set of microcomputers acting as network frontends ("network access machines"), with a local area network (Cambridge Ring) as a common bus. Communication between the hosts and the network access machines uses an interprocessor communication mechanism with a standard transport-level virtualcall interface, which is described. This arrangement provides local hosts with flexible access to any of the networks, and supports a relay system which allows users on one network to access hosts and facilities on any of the other networks.

Implementing the ISO-OSI reference model

Abstract: The ISO-OSI reference model was the design framework for the implementation of a heterogeneous network in a local environment. The HMINET-2 is a network based on standards in data communication. The paper focus on the OSI model feasability and outlines the encountered problems and the adopted solutions in the network design and implementation.

Higher-level protocols are not necessary end-to-end

Abstract: The higher-level communication protocols in computer networks, such as belonging to the OSI Transport through Application layers, are usually considered to have an end-to-end significance, that is the entities executing the protocol reside at the two respective ends of the connection, close to the application users. This question of end-to-end significance was in particular an issue in the discussion of the meaning of acknowledgements in the Transport layer, and in the distinction between the OSI Network and Transport layers. The OSI protocols are developed for the interworking of "Open Systems". It seems that an Open System may be, in particular, a distributed computing system which presents to its environment, for example through a gateway, the protocol behavior defined by OSI. In this case the Open System would use internally, possibly over a local area network, specific protocols, which may or may not be structured according to the OSI Reference Model, but which are different to the protocols defined for OSI. In this case the OSI higher-level protocols would be executed between the entities in the environment of the Open System (e.g. system of user A1) and the gateway of the Open System, which is not end-to-end, as indicated in the figure below. The purpose of this contribution is to point out that this situation can be considered normal (i.e. end-to-end significance is irrelevant) provided that the OSI services have a property, which we call in the following "concatenation property". A service specification has the concatenation property if two service providing subsystems may be concatenated such that the system (consisting of the concatenated subsystems) provides a service which has the same logical properties as the original services. (Clearly, the performance of the concatenated service would in general be lower). It is important to note that we assume that the services of the non-OSI system (e.g. service provider B) are logically identical to those defined for OSI (e.g. service provider A). In this case the concatenation entity has a straightforward function (see below). In the case that they are different, some adaptation may be performed which has, however, an impact on all users and could sometimes result in quite complex gateway functions. The OSI Transport service has the concatenation property to a large extent. It is sufficient to use a concatenation entity that generates service requests to the service provider B for each service indication received from service provider A (with same parameter values). A problem arising, however, is one of addressing. It is necessary that the addressing space within the service provider B be foreseen by the addressing conventions used within the service provider A (and inversely) such that a user connected to the service provider A may select an address which identifies a user connected to the service provider B. It is then necessary that all service indications generated by service provider A destined to users connected to service provider B be generated over the interface to the concatenation entity, and similarly in the opposite direction. Another problem is related to error reporting. It seems that a distinction between connection aborts generated by the user or service provider, respectively, is not possible in the manner defined for OSI. It seems that the services specified for the other higher layers of OSI have similar concatenation properties. We can see two conclusions from the above discussion: (1) If services have the concatenation property the question of end-to-end significance is irrelevant. Gateways may be constructed which realize the concatenation of two or more distributed system services. (2) The service specifications of OSI are the main documents on which the construction of OSI gateways is based. These specifications are therefore essential, not only as a basis for checking the consistency of several protocol layers within the OSI hierarchy, but also as as basis for interworking between existing systems according to OSI.

OSI model layering of a military local network

Abstract: The practical experiences encountered in an early application of the ISO/OSI Reference Model are discussed. The embedding of a new LAN within an existing military communication system is analyzed in accordance with the ISO/OSI Model. The functional layering of the existing system is identified to aid in resolving layering issues of the new network. Structured analysis techniques are applied to organize both connection-oriented and cocrectionless functions of the new network into appropriate layers and define layer interfaces. Some concepts to organize layer management are presented.

Network Design Tool for EHF Satellite Communications Networks

Abstract: : This document describes the design concept of the Network Design Tool. The Network Design Tool (NDT) is a collection of analytical techniques, algorithms and simulation methods that may be used to characterize the performance of a computer communication network. Much work has been done over the past several years in network performance analysis and many techniques have been developed or proposed. Each of these methods applies to a particular aspect of the network design and is based on a particular modeling point of view. We define the computer communication network and then describe the different ways the network may be modeled. Each network model is related to the particular design problem being addressed. The various analytical approaches are briefly described and their relationship to the network models discussed. Chapter 2 is a survey of the major approaches to specific network design problems while Chapters 3 and 4 discuss two fairly well defined areas of network analysis: topological design/optimization and protocol validation. Chapter 5 is a survey of network design tools presently available locally or on the Advanced Research Projects Agency Network (ARPANET). Finally, Chapter 6 presents an outline of the NDT specification.