Local Network Environment Research Articles

CifNet network multi-well data management system

The CifNet network multi-well data management system is developed for 100MB or 1000MB local network environments which are used in Chinese oil industry. The kernel techniques of CifNet system include: 1, establishing a high efficient and low cost network multi-well data management architecture based on the General Logging Curve Theory and the Cif data format; 2, implementing efficient visit and transmission of multi-well data in C/S local network based on TCP/IP protocol; 3, ensuring the safety of multi-well data in store, visit and application based on Unix operating system security. By using CifNet system, the researcher in office or at home can visit curves of any borehole in any working area of any oilfield. The application foreground of CifNet system is also commented.

Stimulated Raman Scattering of Liquid Water under the Strong Focusing Condition: Analysis of Local Hydration Network Environments in Dilute Ethanol Solutions

Stimulated Raman scattering (SRS) of OH stretching vibrations of water molecules is investigated when an intense pulsed beam is focused in liquid water. The SRS is emitted before the phase transition from liquid to plasma, and an enhanced vibrational spectrum is obtained at around 3400 cm-1, the main peak of water in the liquid phase. Despite the strong and perturbing excitation condition, the temperature dependence of the forward SRS spectrum indicates that the SRS sensitively reflects the slight changes of the local hydrogen-bonding network environment in liquid water. The local network environments in dilute ethanol solutions (1−3 mol %) are investigated by utilizing the enhanced vibrational spectrum. Little change is observed in the peak shift of the SRS, indicating the that the perturbation is relatively small as compared to that induced by structure-breaking solutes such as KCl. There is, however, a clear decrease of the intensity on the higher frequency side of the SRS band in ethanol solutions. Al...

Design and implementation of a low-cost/high-performance Video on Demand server

In this paper a prototype of a distributed Video on Demand server is presented. The technical aspects regarding the realization of this kind of service provider are dealt with, paying particular attention to exploiting the architecture the system is based on. The proposed system easily allows, in any broadband local network environment, the realization of a low-cost/high-performance, distributed video server, through the clustering of the local workstations. The system has been implemented and tested, and its performance and scalability results are presented in the final sections of this paper.

Comparative performance analysis of versions of TCP in a local network with a lossy link

We use a stochastic model to study the throughput performance of various transport control protocol (TCP) versions (Tahoe (including its older version that we call OldTahoe), Reno, and NewReno) in the presence of random losses on a wireless link in a local network. We model the cyclic evolution of TCP, each cycle starting at the epoch at which recovery starts from the losses in the previous cycle. TCP throughput is computed as the reward rate in a certain Markov renewal-reward process. Our model allows us to study the performance implications of various protocol features, such as fast retransmit and fast recovery. We show the impact of coarse timeouts. In the local network environment the key issue is to avoid a coarse timeout after a loss occurs. We show the effect of reducing the number of duplicate acknowledgements (ACKs) for triggering a fast retransmit. A large coarse timeout granularity seriously affects the performance of TCP, and the various protocol versions differ in their ability to avoid a coarse timeout when random loss occurs; we quantify these differences. We show that, for large packet-loss probabilities, TCP-Reno performs no better, or worse, than TCP-Tahoe. TCP-NewReno is a considerable improvement over TCP-Tahoe, and reducing the fast-retransmit threshold from three to one yields a large gain in throughput; this is similar to one of the modifications in the TCP-Vegas proposal. We explain some of these observations in terms of the variation of fast-recovery probabilities with packet-loss probability. The results of our analysis compare well with a simulation that uses actual TCP code.

Steady-state analysis of rate-controlled data transport in ATM Local Area Networks

This paper presents a steady-state analysis of rate-based flow control operating with the regular window mechanism of the transport protocol in ATM local area network (LAN) or local high-speed network environments. The rate control schemes are divided into single-threshold and two-threshold cases. By applying Norton's theorem for queuing model simplification and deriving a computation algorithm, the analytical results for steady-state performance of these schemes are found to be computationally efficient and yield accurate approximations. In the numerical results, the rate control schemes have been shown to have significant effects in reducing congestion levels at the receiving entity as well as in the high-speed networks. We also conclude that the two-threshold rate control scheme can be more effective in alleviating network congestion conditions than single-threshold control, while keeping the control overhead (in terms of the rate adjustment frequency) at a low level, provided that threshold values are selected appropriately. The total throughput could be affected, but only in a limited fashion.

The ATM test bed: an experimental platform for broadband communications

The ATM test-bed is a laboratory plant including access facilities and switching functionalities, together with some advanced terminal equipment in an ATM environment. It is the result of research activities addressed to B-ISDN development and carried out in the framework of the Telecommunication Project, a five-year Italian research program organized and supported by the National Research Council (CNR). The aim of the test-bed is to realize a flexible local network environment where critical issues related to the introduction of ATM techniques can be investigated, including signaling, internetworking, and service support, in addition to the basic switching technology. The emphasis is on flexibility and comprehensiveness of features and functionalities, rather than performance and technology. Beyond the technology issues related to the implementation, one of the major aspects of the test-bed is the collaborative development of its various building blocks. >

(N) - LMP: an architecture for the OSI lower layers management

Abstract We propose an integrated architecture called (N)-LMP for network management which can be applied for both OSI local and large network environments. Noting that SNMP and CMIP are complementary and serve two different purposes, we propose to integrate these two approaches within a “CMIP-style” architecture. We also reduce the overhead introduced by CMIP which imposes the implementation of a complete connection-oriented protocol stack by noting that the right place to implement network management protocol for large networks is within the OSI network layer itself rather than in the application layer.

Models for planning capacity expansion in local access telecommunication networks

The rapid progress of communications technology has created new opportunities for modeling and optimizing the design of local telecommunication systems. The complexity, diversity, and continuous evolution of these networks pose several modeling challenges. In this paper, we present an overview of the local telephone network environment, and discuss possible modeling approaches. In particular, we (i) discuss the engineering characteristics of the network, and introduce terminology that is commonly used in the communications industry and literature; (ii) describe a general local access network planning model and framework, and motivate different possible modeling assumptions; (iii) summarize various existing planning models in the context of this framework; and (iv) describe some new modeling approaches. The discussion in this paper is directed both to researchers interested in modeling local telecommunications systems and to planners interested in using such models. Our goal is to present relevant aspects of the engineering environment for local access telecommunication networks, and to discuss the relationship between engineering issues and the formulation of economic decision models. We indicate how changes in the underlying switching and transmission technology affect the modeling of the local telephone network. We also review various planning issues and discuss possible optimization approaches for treating them.

Partition strategy for distributed query processing in fast local networks

A partition-and-replicate strategy for processing distributed queries referencing no fragmented relation is sketched. An algorithm is given to determine which relation and which copy of the relation is to be partitioned into fragments, how the relation is to be partitioned, and where the fragments are to be sent for processing. Simulation results show that the partition strategy is useful for processing queries in fast local network environments. The results also show that the number of partitions does not need to be large. The use of semijoins in the partition strategy is discussed. A necessary and sufficient condition for a semijoin to yield an improvement is provided.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Time server in advanced automation local area network

The unique and accurate time standard is becoming important today, especially in billing calculation, concurrency control and timing control of distributed systems. In the local network environment, many applications are time-dependent. A universal time standard and time protocol are required. This paper will describe the time server, time protocol and the reliability consideration of the time server.

Optimal allocation of file servers in a local network environment

A globally optimal allocation for files in a local network environment is presented. The principal concern is the delays due to contention at the file servers; storage space is assumed to be adequate. A queuing network model is used to represent the file servers and the workstations. The workloads generated by the workstations are statistically identical. The model assumes that the communications medium is lightly loaded. In this case there is very little queuing, so that a message transmission requires an approximately constant average delay which can be included in the local processing time of the workstation. Under these assumptions the model can be applied to any of the various LAN technologies. It is shown that all the files of each workstation should be placed on one file server, with the workstations divided as equally as possible among the file servers.

Design and evaluation of an interface for an integrated service data network

The paper describes the design of an inexpensive microprocessor-based interface that allows the efficient multiplexing of file transfer and interactive data for transmission over a packet network. The interface can be used in a variety of networking applications such as a network interface to a host computer (thus minimizing host software), an intelligent terminal or as the application portion of a network node in a local network environment. An emulation of the interface was performed in order to obtain an insight into the software required for each of the processors.

Mechanisms for a reliable timer-based protocol

Timer-based protocol mechanisms are developed for reliable and efficient transmission of both single-message and message-stream traffic. That is, correct data delivery is assured in the face of lost, damaged, duplicate, and out-of-sequence packets. The protocol mechanisms seem particularly useful in a high-speed local network environment. Current reliable protocol design approaches are not well suited for single-message modes of communication appropriate, for example, to distributed network operating systems. The timer intervals that must be maintained for sender and receiver are developed along with the rules for timer operation, packet acceptance, and connection opening and closing. The underlying assumptions about network characteristics required for the timer-based approach to work correctly are discussed, particularly that maximum packet lifetime can be bounded. The timer-based mechanisms are compared with mechanisms designed to deal with the same problems using the exchange of multiple messages to open and close logical connections or virtual circuits.