Local Area Network Protocol Research Articles

Performance evaluation of ring networks supporting a packet voice service

The performance of three access protocols for ring-shaped local area networks is evaluated in terms of their effectiveness in supporting a packet voice service. The protocols considered are the control token, message slot and buffer insertion. The selection of an optimal packet length that satisfies voice delay requirements is studied. Alternative operating modes of each access protocol are also examined in terms of their contribution to this delay. The paper concludes that, for integrated voice-data networks, the control token and buffer insertion protocols require priority levels to provide voice service with acceptable delay, and the message slot protocol provides a performance worse than the other two access protocols.

Ed-net; A multi-Protocol educational local area network

The last decade has witnessed tremendous productivity in the field of local area networks (LANs). The productivity has ranged from many different available commercial LANs to detailed technical analyses, performance evaluation models and simulation results. The need now arises for networks to teach students in university and engineers in industry how to build and design LANs. The purpose of this paper is to present the Ed-Net; a multi-protocol local area network for educational and design purposes. The network uses available VLSI chips that implement LAN protocols. The intelligent co-processors LAN controllers such as INTEL 82586 for the Ethernet and Western Digital WD 2840 for the token-passing are used. Also advanced encoder/decoder chips such as Seeq 8023 and Harris HD-6409 are utilized. Ed-Net can be configured as an Ethernet, or a tokenpassing bus. Number of experiments can be run on the network. These experiments range from: interfacing the main CPU to the LAN controller, memory sharing, FIFO and DMA operation, error detection, and synchronization to framing, data encryption and successful transmission and reception.

Performance of a CSMA/CD Protocol for Local Area Networks

In this paper we present a performance analysis of a CSMA/CD protocol designed to effectively resolve collisions in a local area network such as Ethernet. We give expressions for the average time required to resolve a collision involving <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</tex> stations and the average time for a particular station involved in a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</tex> -way collision to send its packet successfully. We also consider the efficiency of this protocol and give a lower bound for the maximum efficiency. The above analysis is independent of any particular packet arrival distribution other than the assumptions that in a successful transmission each station is equally likely to be the one transmitting, that in a collision each station is equally likely to be a participant, and that the probability of the simultaneous arrival of packets is zero.

Analysis of the CSMA/CD protocol with deterministic contention resolution

AbstractThe CSMA/CD DCR (CDMA/CD with Deterministic Contention Resolution) is a multiaccess protocol for local area networks. With this protocol a packet collides with another only once at most, so that high throughput and small delay characteristics are achieved. This paper presents a method of analyzing this protocol using a slotted model. First, for the equal arrival rate case, numerical results are obtained and the performance is evaluated on a throughput‐delay characteristic basis. As for the delay characteristic, not only its average but also its variance and distribution are evaluated. Also, the delay characteristics for right‐ and leftmost stations are clarified. Next, the unequal arrival rate case is analyzed and the delay characteristic is studied. Finally, the performance of CSMA/CD DCR is compared with those of CSMA/CD and token scheme, and the application field of CSMA/CD DCR is clarified.

Robot protocols and interfacing to LANs

The paper outlines the features of an ‘intelligent’ interface based on local area network (LAN) protocols, which was designed to enable a variety of computer controlled manufacturing machines to be linked together and integrated with supervisory computers performing control, data-base and production management functions. The use of this interface provides the basis of a general solution to the problems of flexibility and efficient utilization within manufacturing environments. To illustrate the use of the interface, the paper presents some examples of the utilization of shared resources on a computer network to improve the processing facilities available at robot controllers. Also included is a brief discussion of the nature of communication with computer controlled manufacturing machines.

Voice and data performance measurements in L-express net

L-Express is a protocol for Local Area Networks based on a single bus topology. It utilizes a simple and efficient virtual token access scheme which provides ordered and collision-free transmission. This paper presents results of measurements performed to investigate in details the behavior of the L-Express protocol under different network speeds, configurations and traffic environments. The measurements are obtained using a mix of simulation and field tests on a network prototype. Voice and integration of voice and data are also taken into account. The results indicate a good behavior (compared with Ethernet) for small size networks (500 m) and Low data rates (10 Mb/s) as well as for Large size networks (5000 m) and high data rates (100 Mb/s).

Design and validation of a transport protocol for local area networks

A transport protocol design for local area networks is presented. The service offered to the Transport layer is assumed to be an unacknowledged connectionless service. The Transport layer provides a reliable, in-sequence, connection-oriented service to the Session layer. Messages of two priority levels are provided. To bridge the gap between the above two services, the Transport layer performs a set of functions, such as error recovery, flow control, duplicate detection, sequencing, etc. The transport protocol provides the means for establishing, maintaining and releasing transport connections. The protocol is analysed by using a perturbation technique based on reachability analysis.

Proving liveness for networks of communicating finite state machines

Consider a network of communicating finite state machines that exchange messages over unbounded FIFO channels. Each machine in the network can be defined by a directed graph whose nodes represent the machine states and whose edges represent its transitions. In general, for a node in one of the machines to be live (i.e., encountered infinitely often during the course of communication), each machine in the network should progress in some fair fashion. We define three graduated notions of fair progress (namely, node fairness, edge fairness, and network fairness), and on this basis we define three corresponding degrees of node liveness. We discuss techniques to verify that a given node is live under each of these fairness assumptions. These techniques can be automated; and they are effective even if the network under consideration has an infinite number of reachable states. We use our techniques to establish the liveness of some practical communication protocols; these include an unbounded start-stop protocol, an unbounded alternating bit protocol, and a simplified version of the CSMA/CD protocol for local area networks.

Tokenless Protocols for Fiber Optic Local Area Networks

A family of LAN (Local Area Network) protocols is presented. The LAN consists of a pair of unidirectional fiber optic buses to which stations are connected via passive taps. The protocols provide round-robin bounded delay access to all stations. Contrary to most roundrobin access schemes, the protocols do not require transmission of special packets (tokens); rather, they simply rely on the detection of bus activity at each station. The performance of these protocols in various traffic conditions and system configurations is evaluated via analysis and simulation.

An Optical Fiber-Based Integrated LAN for MAGNET's Testbed Environment

MAGNET is a Network Testbed (NTB) designed to evaluate the performance of local area network architectures and protocols supporting integrated services such as televideo, video conferencing, telephone, computer communication, and facsimile. The integrated local area network (ILAN) presented in this paper has been designed to support the research activities intended for MAGNET. An active slotted ring topology was chosen to implement adaptive sequential-type access mechanisms that are a function of the network loading. The ILAN is based on fiber optic technology with wavelength-division multiplexing of two 100 Mbit/s channels. The media-access protocol provides higher levels with the capability of implementing two modes of operation referred to as circuit-switching, and packet-switching modes, respectively. Provisions have also been made for implementing simultaneous scheduling as well as centralized and decentralized access control schemes. Finally, the reconfigurable structure of the network testbed enables the study of the reliability and availability of ILAN's.

A Hybrid Multiple-Access Protocol for Data and Voice-Packet Over Local Area Networks

This correspondence presents HYMAP, a hybrid multiple access protocol for local area networks. The protocol combines features of both CSMA/CD and a collision-free protocol. Control is transferred from one protocol to the other according to state information sensed on the channel. The performance of HYMAP is evaluated by computer simulation for both data and voice packets. It compares favorably to other well-known multiple-access protocols. The number of packet-voice terminals that can be supported by HYMAP is higher than that obtained by using other protocols. Statistical analysis of the simulation results is also given.

A real-time flood-routed voice protocol for fibre optic local area networks

A simple real-time flood routing voice (RTFRV) protocol which is suitable for point-to-point arbitrarily connected fibre optic local area networks is described. Simulation on a 3 Mbit/s nine-node mesh network which employs the protocol has shown that it is capable of supporting about 50 simultaneous two-way voice conversations (or 100 users) with packet delay of less than 10 ms and without any loss of information. The overall results suggest that voice transmission on such a network is feasible and that it performs better than voice transmission over Ethernet. Furthermore, the network is also very robust and allows easy network reconfiguration.

Correction to "Overview of a Broad-Band Local Area Network Protocol Architecture"

Correction to "Overview of a Broad-Band Local Area Network Protocol Architecture"

A New CSMA-CD Protocol for Local Area Networks with Dynamic Priorities and Low Collision Probability

This paper reports on the implementation of a local area network (LAN) operating under a new CSMA-CD protocol with dynamic priorities (CSMA-CD-DP). User terminals, host computers, and other servers are connected to a common broad-band channel through N network access stations in a clustered manner. This concept reduces the number of network access stations and enhances the utilization of hardware and software resources greatly. A new protocol has been developed which organizes the decentralized operation of the distributed network access stations and which allows for a number of specific features. In the idle state the channel is operated in the contention mode. After the beginning of a transmission, the channel is operated in a reservation mode. Channel arbitration after a completed transmission is resolved by staggered delays; at any time, each station owns a distinct transmission delay which is changed after every successful transmission by broadcasted acknowledgments. This protocol strictly limits the possibility of collisions and approaches the effectiveness of token and polling protocols with increasing load. Through specific allocations of transmission delays, static priorities or dynamic overload control can be realized easily. The performance of the CSMA-CD-DP protocol has been modeled and analyzed analytically as well as by simulation. Results for normal load and overload reveal high throughput and low transfer times which are basic for a wide range of applications in LAN's.

LAN Protocol Validation and Evaluation

We are using simulation to validate and evaluate the performance of the proposed IEEE 802.4 Token-Passing Bus Medium Access Control (MAC) Protocol for local area networks. We will use our discussion of this modeling study to present our technique for protocol validation. We will also present some of our validation and performance results. Our modeling technique is unusual in two important respects. First, it transforms the formal specification of the protocol by a direct and simple technique into a simulation program. Second, testable assertions about the protocors expected behavior, under both normal and abnormal conditions, are easily transformed into simulation test cases. Our protocol validation technique runs test cases on the simulation model. These test cases are based upon "behavioral assertions" which were derived from the design objectives and expected use of the protocol. Our validation results are discussed in terms of the behavioral assertions tested and the success or failure of meeting these assertions. We also report on simulation performance predictions for some special test cases.

Overview of a Broad-Band Local Area Network Protocol Architecture

The protocol architecture of a broad-band local area network (LAN) must consider a realm of issues ranging from user device requirements to the characteristics of the underlying broad-band cable medium. The primary environment for which these protocols are intended consists of a collection of multichannel broad-band local networks, connected by point-to-point links. This paper describes one example of a broad-band LAN protocol architecture, LocalNet ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</sup> Sytek Inc.). Particular attention is paid to those design decisions and practical considerations which were prompted by the intended environment.

ICs interface keyboard to microprocessor : Donald P. Martin and Kerry S. Berland. Electronics March 6 1975. p. 83

Multiuser Multi-Packet Transmission (MPT) from an Access Point (AP) equipped with multiple antennas to multiple single-antenna nodes can be achieved by exploiting the spatial dimension of the channel. In this paper we present a queueing model to analytically study such systems from the link-layer perspective, in presence of random packet arrivals, heterogeneous channel conditions and packet errors. The analysis relies on a blind estimation of the number of different destinations among the packets waiting in the queue, which allows for building a simple, but general model for MPT systems with per-node First-In First-Out (FIFO) packet scheduling. Simulation results validate the accuracy of the analytical model and provide further insights on the cross-relations between the channel state, the number of antennas, and the number of active users, as well as how they affect the system performance. The simplicity and accuracy of the model makes it suitable for the evaluation of Medium Access Control (MAC) protocols for Ad Hoc or Wireless Local Area Networks supporting Multiuser MPT in non-saturation conditions, where the queueing dynamics play an important role on the achieved performance, and simple user selection algorithms are required.