87 research outputs found

    OSI in the NASA science internet: An analysis

    Get PDF
    The Open Systems Interconnection (OSI) protocol suite is a result of a world-wide effort to develop international standards for networking. OSI is formalized through the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). The goal of OSI is to provide interoperability between network products without relying on one particular vendor, and to do so on a multinational basis. The National Institute for Standards and Technology (NIST) has developed a Government OSI Profile (GOSIP) that specified a subset of the OSI protocols as a Federal Information Processing Standard (FIPS 146). GOSIP compatibility has been adopted as the direction for all U.S. government networks. OSI is extremely diverse, and therefore adherence to a profile will facilitate interoperability within OSI networks. All major computer vendors have indicated current or future support of GOSIP-compliant OSI protocols in their products. The NASA Science Internet (NSI) is an operational network, serving user requirements under NASA's Office of Space Science and Applications. NSI consists of the Space Physics Analysis Network (SPAN) that uses the DECnet protocols and the NASA Science Network (NSN) that uses TCP/IP protocols. The NSI Project Office is currently working on an OSI integration analysis and strategy. A long-term goal is to integrate SPAN and NSN into one unified network service, using a full OSI protocol suite, which will support the OSSA user community

    Internetworking: an analysis and proposal

    Get PDF
    As the number of computer networks has grown, so has the desire for users on these networks to communicate with each other, thus the need for internetworking. Unfortunately, many of these networks were not designed with internetworking capabilities in mind. The internetworking facilities offered by a typical network range from non-existent to state of the art. Two major efforts towards internetworking are the DARPA Internet protocols and the OSI Internetworking protocols. The goals of this thesis are to acquaint the reader with the qualities which are desired in an internetworking scheme, to describe how internetworking is accomplished currently, and how these protocols might be modified to better suit the needs of the internetwork user. To this end, this thesis will develop the functional requirements for an ideal internetwork, describe two current methods for internetworking, and analyze these methods against the ideal internetwork. The advantages and disadvantages of each internetworking method will be discussed. After this analysis, suggestions will be made as to how these internetworking schemes could more closely resemble the ideal internetwork

    Avoiding Loops and Packet Losses in ISP Networks

    Get PDF
    Even in well managed Large ISP networks failures of links and routers are common Due to these failures the routers update their routing tables Transient loops can occur in the networks when the routers adapt their forwarding tables In this paper a new approach is proposed that lets the network converge to its optimal state without loops and the related packet lossless The mechanism OUTFC-Ordered Updating Technique with Fast Convergence is based on an ordering of the updates of the forwarding tables of the routers and fast convergence Typically we have chosen a Network consisting of routers and Link costs for simulation Link failures are simulated Avoiding transient loops in each case is demonstrated by constructing a Reverse Shortest PathTree RSP

    Communication Architecture For Distributed Interactive Simulation (CADIS): Military Standard (draft)

    Get PDF
    Report establishes the requirements for the communication architecture to be used in a distributed interactive simulation, including the standards and the recommended practices for implementing the communication architecture and the rationales behind them

    Prospects for Internet technology

    Get PDF
    This paper surveys the current developments in Internet technology, with a particular emphasis on performance, and the growing need for various guarantees of quality of service. It discusses hardware technologies for increased bandwidth, mechanisms for requesting and providing specific qualities of service, and various scaling issues. Fi-nally it discusses mechanisms needed for (but not the economics of) the Internet in the mass market. To this end, we survey changes in the areas of addressing, and flow management. 1

    Digital document imaging systems: An overview and guide

    Get PDF
    This is an aid to NASA managers in planning the selection of a Digital Document Imaging System (DDIS) as a possible solution for document information processing and storage. Intended to serve as a manager's guide, this document contains basic information on digital imaging systems, technology, equipment standards, issues of interoperability and interconnectivity, and issues related to selecting appropriate imaging equipment based upon well defined needs

    Accuracy and Dynamics of Hash-Based Load Balancing Algorithms for Multipath Internet Routing

    Get PDF
    This paper studies load balancing for multipath Internet routing. We focus on hash-based load balancing algorithms that work on the flow level to avoid packet reordering which is detrimental for the throughput of transport layer protocols like TCP. We propose a classification of hash-based load balancing algorithms, review existing ones and suggest new ones. Dynamic algorithms can actively react to load imbalances which causes route changes for some flows and thereby again packet reordering. Therefore, we investigate the load balancing accuracy and flow reassignment rate of load balancing algorithms. Our exhaustive simulation experiments show that these performance measures depend significantly on the traffic properties and on the algorithms themselves. As a consequence, our results should be taken into account for the application of load balancing in practice
    corecore