A programmable network interface unit for hybrid meshnet local area networks

Graduation date: 1993A Hybrid Meshnet LAN, a new local area network architecture, has been\ud proposed by Dr. Cheoul-Shin Kang and Dr. James Herzog. It provides for distributed\ud control hybrid architecture which is good for effective load sharing under various local\ud area network environments. Hybrid Meshnet has a dual channel structure, a token ring\ud and a collection of full-duplex data links. The multiple high-speed transmissions,\ud private and secure communications and large volume of data transmission capability are\ud some of the features of Hybrid Meshnet.\ud The design features necessary to implement the network interface unit (NIU) for\ud the Hybrid Meshnet are presented. The unit is a multiprocessor system with each\ud processor having a RISC-like architecture. Various asynchronous activities are\ud distributed among the three processors resulting in a balanced network interface unit.\ud Except for the time critical and non-varying functions, all the functionalities of the\ud unit are programmable. The hybrid meshnet protocol is still in the development stage.\ud The programmable unit will accommodate the changes in the protocol. The network\ud interface unit will be compatible with most of the host computer systems.\ud The study is one step forward in the direction of Hybrid Meshnet Local Area\ud Network's implementation

Design and analysis of a medium access and control strategy for extending the ISDN services to LAN users

A significant portion of the contemporary research efforts in the area of data communications and computer networking is devoted to Local Area Networks (LANs) and Integrated Services Digital Networks (ISDNs). Both, ISDN and LAN, are being developed to satisfy the key requirements of their specific applications. This application specific development has created a semantic gap between ISDN and LANs. Consequently, an extensive mapping is required to interface an ISDN with a LAN. Obviously, such mapping may limit the overall performance of a LAN;In this dissertation, a Medium Access and Control Strategy (MACS) is proposed that does not require a complex ISDN/LAN interface and extends the ISDN services to a LAN user without degrading the performance of the LAN. The proposed MACS is distributed in nature, supports a prioritized realtime traffic (using dynamically controlled target token rotation time), provides packet switching and circuit switching facilities, and can be implemented on a single ring topology;The analysis of the strategy indicates that a channel capacity of 64 Kbps is sufficient to carry the control and signalling information for 100 stations. The simulation results show that the network performance is drastically degraded at lower values of the target token rotation time. The proposed strategy solves this problem by dynamically adjusting the target token rotation time

Spacelab system analysis: A study of the Marshall Avionics System Testbed (MAST)

An analysis of the Marshall Avionics Systems Testbed (MAST) communications requirements is presented. The average offered load for typical nodes is estimated. Suitable local area networks are determined

Collision Avoidance Tree networks

The Collision Avoidance Tree is a new local area network based on a hardware device called collision avoidance switch, which arbitrates random access to a shared communications channel. Collision Avoidance Tree combines the benefits of random access (low delay when traffic is light; simple, distributed, and therefore robust, protocols) with concurrency of transmission, excellent network utilization and suitability for the domain of high-speed, optical networking.The Collision Avoidance Tree is classified in two classes: the Collision Avoidance Single Broadcast (CASB) Tree and the Collision Avoidance Multiple Broadcast (CAMB) Tree. The CASB Tree allows only a single transmission on the network at a given time, while the CAMB Tree is more general and allows concurrent transmissions on the network.This paper describes network architectures (e.g., station and switch protocols) and designs and implementations of the CASB and CAMB Trees. Performance results derived from analyses, simulations, measurements of experimental networks are also presented

Distributed computing system with dual independent communications paths between computers and employing split tokens

This is a distributed computing system providing flexible fault tolerance; ease of software design and concurrency specification; and dynamic balance of the loads. The system comprises a plurality of computers each having a first input/output interface and a second input/output interface for interfacing to communications networks each second input/output interface including a bypass for bypassing the associated computer. A global communications network interconnects the first input/output interfaces for providing each computer the ability to broadcast messages simultaneously to the remainder of the computers. A meshwork communications network interconnects the second input/output interfaces providing each computer with the ability to establish a communications link with another of the computers bypassing the remainder of computers. Each computer is controlled by a resident copy of a common operating system. Communications between respective ones of computers is by means of split tokens each having a moving first portion which is sent from computer to computer and a resident second portion which is disposed in the memory of at least one of computer and wherein the location of the second portion is part of the first portion. The split tokens represent both functions to be executed by the computers and data to be employed in the execution of the functions. The first input/output interfaces each include logic for detecting a collision between messages and for terminating the broadcasting of a message whereby collisions between messages are detected and avoided

Mapping Technological Trajectories as Patent Citation Networks. An application to Data Communication Standards

Technical systems, Technological trajectories, Patents, Network analysis, Data communications

Modeling of the Space Station Freedom data management system

The Data Management System (DMS) is the information and communications system onboard Space Station Freedom (SSF). Extensive modeling of the DMS is being conducted throughout NASA to aid in the design and development of this vital system. Activities discussed at NASA Ames Research Center to model the DMS network infrastructure are discussed with focus on the modeling of the Fiber Distributed Data Interface (FDDI) token-ring protocol and experimental testbedding of networking aspects of the DMS

Telemetry downlink interfaces and level-zero processing

The technical areas being investigated are as follows: (1) processing of space to ground data frames; (2) parallel architecture performance studies; and (3) parallel programming techniques. Additionally, the University administrative details and the technical liaison between New Mexico State University and Goddard Space Flight Center are addressed

Analysis of a class of distributed queues with application

Recently we have developed a class of media access control algorithms for different types of Local Area Networks. A common feature of these LAN algorithms is that they represent various strategies by which the processors in the LAN can simulate the availability of a centralized packet transport facility, but whose service incorporates a particular type of change over time known as 'moving sever' overhead. First we describe the operation of moving server systems in general, for both First-Come - First-Served and Head-of-the-Line orders of service, together with an approach for their delay analysis in which we transform the moving server queueing system into a conventional queueing system having proportional waiting times. Then we describe how the various LAN algorithms may be obtained from the ideal moving server system, and how a significant component of their performance characteristics is determined by the performance characteristics of that ideal system. Finally, we evaluate the compatibility of such LAN algorithms with separable queueing network models of distributed systems by computing the interdeparture time distribution for M/M/1 in the presence of moving server overhead. Although it is not exponential, except in the limits of low server utilization or low overhead, the interdeparture time distribution is a weighted sum of exponential terms with a coefficient of variation not much smaller than unity. Thus, we conjecture that a service centre with moving server overhead could be used to represent one of these LAN algorithms in a product form queueing network model of a distributed system without introducing significant approximation errors

Advanced local area network concepts

Development of a good model of the data traffic requirements for Local Area Networks (LANs) onboard the Space Station is the driving problem in this work. A parameterized workload model is under development. An analysis contract has been started specifically to capture the distributed processing requirements for the Space Station and then to develop a top level model to simulate how various processing scenarios can handle the workload and what data communication patterns result. A summary of the Local Area Network Extendsible Simulator 2 Requirements Specification and excerpts from a grant report on the topological design of fiber optic local area networks with application to Expressnet are given