Showing papers on "Communications protocol published in 1995"

Link-sharing and resource management models for packet networks

Abstract: Discusses the use of link-sharing mechanisms in packet networks and presents algorithms for hierarchical link-sharing. Hierarchical link-sharing allows multiple agencies, protocol families, or traffic types to share the bandwidth on a link in a controlled fashion. Link-sharing and real-time services both require resource management mechanisms at the gateway. Rather than requiring a gateway to implement separate mechanisms for link-sharing and real-time services, the approach in the paper is to view link-sharing and real-time service requirements as simultaneous, and in some respect complementary, constraints at a gateway that can be implemented with a unified set of mechanisms. While it is not possible to completely predict the requirements that might evolve in the Internet over the next decade, the authors argue that controlled link-sharing is an essential component that can provide gateways with the flexibility to accommodate emerging applications and network protocols. >

Network-based multimedia communications and directory system and method of operation

Abstract: A communications system (10) is provided which comprises a plurality of network hubs (12, 14 and 16). Network hubs (12, 14 and 16) are interconnected through a communications network (18). The system (10) interconnects messaging systems (24, 26, 28, 30, 32, 34, 36, 40, 42 and 44) having disparate capabilities and using disparate communications protocols. The network hubs use numbers of connection processors (52 and 54) to interact with the messaging systems. A hub database (68) and message store (58) are used to store control information and messaging information within the network hubs. A network processor (60) is used to interact with other hubs within the communications system (10). A message router (72), connection manager (74), data replicator (76), and an administrative event manager (78) are used to control the operations of the hub in processing a message.

Floor acquisition multiple access (FAMA) for packet-radio networks

Abstract: A family of medium access control protocols for single-channel packet radio networks is specified and analyzed. These protocols are based on a new channel access discipline called floor acquisition multiple access (FAMA), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. Control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. The minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. The medium access collision avoidance (MACA) protocol proposed by Karn and variants of CSMA based on collision avoidance are shown to be variants of FAMA protocols when control packets last long enough compared to the channel propagation delay. The throughput of FAMA protocols is analyzed and compared with the throughput of non-persistent CSMA. This analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of MACA in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent CSMA when no hidden terminals exist.

System for extending present open network communication protocols to communicate with non-standard I/O devices directly coupled to an open network

Abstract: An open network system for supporting input/output (I/O) operations for non-standard I/O devices are disclosed. The system includes a server coupled to a plurality of I/O devices through an open network and an extended open system protocol that supports communication with devices that are not personal computers (PCs). These devices include magnetic stripe readers, check readers, smart card readers, credit card terminals, screen phone terminals, PIN pads, printers, and the like. The extended open network protocol includes tags which identify device and input operations and attributes which identify the location, data exchange method, and data variable names for the retrieval, acquisition, and submission of data between the server and I/O devices. Preferably, the open network protocol is implemented in a Hyper Text Transport Protocol (HTTP). Preferably, the system includes a common gateway interface (CGI) at the server which converts protocol statements communicated between the server and I/O devices to application language statements for providing data to an application program coupled to the server. Most preferably, the application statements and protocol statements are constructed in integrated statements with an editor. The editor ensures that data identifiers in the application and protocol statements are compatible. The integrated statements are then parsed by the editor to segregate the protocol statements from the application statements. The protocol statements are downloaded in a file to a client program at an I/O device for processing. The application statements are stored in a file for use by the application. In this manner, generation of the files for client and application processing are automatically done without the user ensuring the correlation of the data fields in the two files.

Distributed multimedia and QOS: a survey

Abstract: Quality of service (QOS) is increasingly important for all components within distributed multimedia systems, as this survey reveals. We discuss the QOS parameters found in communication protocols, operating systems, multimedia databases and file servers, as well as those directly affecting the human user. >

Integrated request-response system and method generating responses to request objects formatted according to various communication protocols

Abstract: A method and apparatus is provided to accomplish creation and serving of data objects among various communication protocols. The method and apparatus can be used in such applications as an on-line classified advertising system on the Internet involving the World Wide Web and electronic mail. In the apparatus, a request decoder receives an incoming request, decodes the request using configurations from a configuration database in order to identify which protocol was used to transmit the request, and generates from the request a corresponding abstract data object. A data processor merges data from a main database with the abstract data object. An object formatter formats the abstract data object including the merged data. An object deliverer formats the object for outgoing transmission according to a protocol of an intended recipient. The functions of object deliverer may be performed by the object formatter.

Apparatus and method for providing decoupled data communications between software processes

Abstract: A communication interface for decoupling one software application from another software application such communications between applications are facilitated and applications may be developed in modularized fashion. The communication interface is comprised of two libraries of programs. One library manages self-describing forms which contain actual data to be exchanged as well as type information regarding data format and class definition that contain semantic information. Another library manages communications and includes a subject mapper to receive subscription requests regarding a particular subject and map them to particular communication disciplines and to particular services supplying this information. A number of communication disciplines also cooperate with the subject mapper or directly with client applications to manage communications with various other applications using the communication protocols used by those other applications.

Verification of the Futurebus+ cache coherence protocol

Abstract: We used a hardware description language to construct a formal model of the cache coherence protocol described in the draft IEEE Futurebus+ standard. By applying temporal logic model checking techniques, we found several errors in the standard. The result of our project is a concise, comprehensible and unambiguous model of the protocol that should be useful both to the Futurebus+ Working Group members, who are responsible for the protocol, and to actual designers of Futurebus+ boards.

Network processor for transforming a message transported from an I/O channel to a network by adding a message identifier and then converting the message

Abstract: A system and method for distributing application-to-application network communications protocol processing Host computers implement distributed API processing across a high speed I/O channel increasing throughput The application API conforms to standard protocols but protocol processing is distributed using a cross-channel distributed sockets API at the session layer This API allows multiplexing of data from one or more hosts to one or more front end routers managing network communications Multiplexing increases network performance through parallel processing and advantageously employs host high speed I/O functions Front end routers perform lower level protocol tasks necessary to exchange data over the communications network

Principles, protocols, and architecture

Abstract: This reference has now been divided into two volumes to reflect the most recent changes in the field. Volume 1 provides a broad, conceptual introduction to the TCP/IP internetworking protocols and the connected TCP/IP Internet. It reviews network hardware, including wide area national backbones ARPANET and NSFNET, and local area technologies Ethernet and token rings. Addresses binding (ARP) and the IP concepts of connectionless datagram delivery, error detection and control, multicasting, and routing are covered. In addition, Comer compares the ISO 7-layer reference model to the TCP/IP 5-layer model in his discussion of protocol layering.

Optimizing World-Wide Web for weakly connected mobile workstations: An indirect approach

Abstract: Modern portable computers and wireless connections over cellular telephone networks have created a new platform for distributed information processing. We have designed a communication architecture that makes it possible to exploit the existing TCP/IP communication protocols but that also takes into account specific features of cellular links. Our communication architecture is based on the concept of indirect interaction. The mediating interceptor is the bridge between the worlds of wireless and wireline communication. It also provides enhanced functionality that improves fault-tolerance and performance. In this paper we demonstrate how the architecture is used to improve the performance of the WWW information browsing. Similar solution methods can be applied to other existing applications and protocols. >

Diagnosis system for motor vehicle

Abstract: A diagnosis system conducts diagnosis with data read out of an electronic control unit with a communications protocol installed in a vehicle. The system has an integrated circuit to be an communications interface suitable for the protocol. The circuit can be made suitable for any communications protocol by reprogramming logical functions of the circuit with design information. Instead of such circuit, the system may have a main processor and a subprocessor. On one hand, the main processor conducts virtual data communication with the control unit for diagnosis. On the other hand, the subprocessor executes a communications processing program suitable for the protocol to have data communication with the control unit. The subprocessor receives data from the main processor and transfers the data to the control unit and vice versa for the virtual data communication.

A framework for network protocol software

Abstract: Writing software to control networks is important and difficult. It must be efficient, reliable, and flexible. Conduits+ is a framework for network software that has been used to implement the signalling system of a mullti-protocol ATM access switch. An earlier version was used to implement TCP/IP. It reduces the complexity of network software, makes it easier to extend or modify network protocols, and is sufficiently efficient. Conduits+ shows the power of a componentized object-oriented framework and of common object-oriented design patterns.

System and method for establishing communication protocols between application programs

Abstract: A method and system for implementing a common protocol for communication of data between a first application program and a second application program. The method and system uses a high level interface specification that is created in a computer program language-independent fashion using an object oriented paradigm. The high level interface specification is used to define the common protocol, and to generate first and second protocol interfaces. Either of the generated first and second protocol interfaces is capable of performing the services of a client or server, and are inserted into the first and second application programs respectively. The first and second protocol interfaces are executed by the first and second application programs for communication of data between them using the common protocol.

Optical communication system

Abstract: PURPOSE:To simultaneously operate plural communication systems while using the same communication medium by allocating different wavelengths to the communication protocol units of information to be transferred inside the same medium for optical transmission. CONSTITUTION:As optical frequency divided and multiplexed optical signals, optical signals at frequencies fa-fc are propagated inside an optical fiber 10. On the other hand, concerning nine optical communication nodes 21-29 performing the communication while being connected to the optical fiber 10, the optical communication nodes 21, 24 and 27 perform the communication according to a communication protocol A, the optical communication nodes 22, 25 and 28 perform the communication according to a communication protocol B, and the optical communication nodes 23, 26 and 29 perform the communication according to a communication protocol C. Concerning these optical communication protocols, the optical signals frequency-divided into three ranger are allocated to three communication protocols A-C existent inside the system, and the respective optical communication nodes 21-29 perform the communication while using the optical signals at the frequencies fa-fc allocated to the communication protocols to which their nodes themselves belong.

Adaptive network protocol independent interface

Abstract: A protocol independent method of transmitting a data packet from a first application program executing on a first device which is interfaced to a LAN to a second application program executing on a second device which is interfaced to the LAN. A protocol independent interface (PII) program is initialized which determines which protocols are available for use, assigns an access line to each protocol that is available for use, assigns an access ID to the first application program, and creates mapping information that indicates a one-to-one correspondence between an access ID/access line pair and a block of protocol specific information which includes a protocol header having predetermined address data. A data packet is sent to the PII program together with the access ID of the first application program and a destination ID for the second application program, and one of the available protocols is selected to transmit the data packet. A block of protocol specific information is retrieved from the mapping information based on the access ID of the first application program and the access line corresponding to the selected protocol, and a transmission packet is formed which includes the data packet, the destination ID, and the retrieved block of protocol specific information. The transmission packet is then transmitted via the LAN.

Interfacing Incompatible Protocols Using Interface Process Generation

Abstract: During system design, one or more portions of the system may be implemented with standard components that have a fixed pin structure and communication protocol. This paper described a new technique, interface process generation, for interfacing standard components that have incompatible protocols. Given an HDL description of the two protocols, we present a method to generate an interface process that allows the two protocols to communicate with each other.

Distributed network computing over local ATM networks

Abstract: Communication between processors has long been the bottleneck of distributed network computing. However, recent progress in switch-based high-speed local area networks (LANs) may be changing this situation. Asynchronous transfer mode (ATM) is one of the most widely-accepted and emerging high-speed network standards which can potentially satisfy the communication needs of distributed network computing. We investigate distributed network computing over local ATM networks. We first study the performance characteristics involving end-to-end communication in an environment that includes several types of workstations interconnected via a Fore Systems' ASX-100 ATM switch. We then compare the communication performance of four different application programming interfaces (APIs). The four APIs were Fore Systems' ATM API, the BSD socket programming interface, Sun's remote procedure call (RPC), and the parallel virtual machine (PVM) message passing library. Each API represents distributed programming at a different communication protocol layer. We evaluated two popular distributed applications, parallel matrix multiplication and parallel partial differential equations, over the local ATM network. The experimental results show that network computing is promising over local ATM networks, provided that the higher level protocols, device drivers, and network interfaces are improved. >

Deterministic network protocol

Abstract: A deterministic network protocol for connecting critical sensors, actuators and computing elements on a bi-directional, time-multiplexed, fiber optic or other media data bus, such that critical messages have concisely bounded latency and non-critical messages may be sent without impacting critical messages. It is a unique combination of a time-slot allocation protocol and a contention-based protocol in which global synchronization information is passed on the data media via a synchronization beacon.

A multi-sender asynchronous extension to the AER protocol

Abstract: The address-event representation (AER) is an asynchronous point-to-point communications protocol for silicon neural systems. This paper describes an extension of the AER protocol that allows multiple AER senders to share a common bus. A fully-functional silicon implementation of the extended protocol is described, as well as a functional board-level system of several of these chips sharing a common bus.

Reasoning about accountability in protocols for electronic commerce

Abstract: A new framework is proposed for the analysis of communication protocols that require accountability, such as those for electronic commerce. Informal arguments are presented to show that a heretofore un-explored property "provability" is pertinent to examine the potential use of communication protocols in the context of litigation, and in the context of audit. A set of postulates which are applicable to the analysis of proofs in general (e.g., zero knowledge proofs), and the proofs of accountability in particular, are proposed. The proposed approach is more natural for the analysis of accountability then the existing belief logics that have been used in the past for the analysis of key distribution protocols. Some recently proposed protocols for electronic commerce and public-key delegation are analyzed to illustrate the use of the new analysis framework in detecting (and suggesting remedies for eliminating) their lack of accountability, and in detecting and eliminating redundancies. >

Integrated wiring systems for a vehicle control system

Abstract: An integrated wiring system for controlling multiple vehicle systems comprising a plurality of terminal control units having different information processing speed and a central control unit. A communications interface is provided in the central control unit in the form of a dedicated programmable input/output processor for performing data communication based on a plurality of communication protocols.

Classical IP and ARP over ATM

Abstract: This paper gives a self{contained description of classical IP (internet protocol) and ARP (address resolution protocol) over ATM (asynchronous transfer mode) and describes a model facilitating the implementation of the switched virtual circuit{ based local area network ATM subnet model. Its contents are distilled from the design and implementation of a prototype of a device driver for this particular subnet model. The work was conducted at the Computer Science Laboratory (CSL) at the Xerox Palo Alto Research Center (PARC). We outline the main features of the two technologies, establish their importance as data communication paradigms, motivate their integration, and sketch several scenarios of their interaction. We concentrate on one speci c scenario: the utilization of ATM as a logical IP subnetwork. Building blocks of this approach are the ATM address resolution protocol as a unicast server based emulation of the classical broadcast address resolution protocol, and connection management functionality as provided by the Q.2931 protocol. The manipulation of transmitted network protocol data units between their submission to the network layer and their transmission by ATM are detailed in an appendix. These explanations are structured analogous to the lower layers in the IEEE local area network model. The complexity and intricacy of the logical IP subnetwork (LIS) approach motivate the development of a model describing the interaction of all participants in an LIS. The devised model is based on a nite automaton. It instruments a structured implementation and it assists in convincing the implementor of the completeness and correctness of the implementation by facilitating its gradual testing and extension.

The Time-Triggered Approach to Real-Time System Design

Abstract: In this paper the basic assumptions that govern the design of timetriggered(TT) real-time systems are examined and the characteristic properties of these architectures are analyzed. The paper introduces a real-time system model and discusses the important concept of temporal accuracy of real-time data. The fundamental paradigm behind the time-triggered design approach is explained in detail. The services and the basic design principles of the time-triggered communication protocol TTP are presented. Finally, the services of a TT architecture are assessed from the points of view of predictability, testability. resource utilization, and assumption coverage.

Model-based software engineering

Abstract: The methodology. Software production as an industrial activity. Distributed systems. The structured paradigm. The object oriented paradigm. Formal methods. Introducing the Protob methodology. The Protob language. Analysis and verification of Protob models. Information modelling with Quid. The Artifex support environment. Case studies. Computer integrated manufacturing. Real-time systems. Distributed systems. Communication protocols.

Automotive diagnostic communications

Abstract: Automotive vehicle electronic devices are diagnosed through communication with a flexible diagnostic tool which automatically switches between a wide variety of communications protocols as required for diagnostic communication tasks presented to the tool. Simultaneous communication with a plurality of devices under a plurality of communications protocols is supported by the tool wherein communication hardware is available for parallel communications under the various protocols via various communication channels and is apportioned for each active diagnostic communication task for the duration of that task.

DACAPO: a distributed computer architecture for safety-critical control applications

Abstract: An architecture for a highly dependable real-time computer network is presented. The architecture and communication protocol are suited for cyclic time-deterministic applications typically found in embedded control systems. Particular attention has been directed towards the requirements of safety-critical automotive control systems. The scheduling of both network communication and application processes is determined at compile time and is thus completely deterministic. A DACAPO system consists of a number of nodes communicating over two serial buses. Each node is composed of two sets of functionally identical fail-silent units, thus providing tolerance against any single fault. A high degree of error detection coverage and the tolerance towards transient faults inherently associated with cyclic operation combine to yield an architecture with a very high safety level.

Low power communications protocols: paging and beyond

Abstract: Paging subscriber devices leverage multiple technologies to achieve low power and long battery life: semiconductors, circuits, systems architecture and network protocol. While many types of electronic devices have capitalized on low-power features for several of these technologies, few other than personal paging services have taken advantage of opportunities presented by well designed protocols with explicit power-reduction features. This paper will review the state-of-practice in existing paging services, and discuss the relevance of such techniques to other wireless communication systems.

Method and apparatus for printing a document over a network

Abstract: A network protocol and hardware interface (240) facilitates high speed transmission of raster data from a host computer (166) having a raster image processor (214) to a printer (160). The protocol and hardware interface (240) of the present invention minimize memory-to-memory transfers of raster data by defining data transfers directly from local memory (248) of network hardware (244) to memory associated with a raster connection management module (256). The protocol defines a first sub-protocol for negociating a connection and preparing to transmit a print job, and a second sub-protocol for transmitting a large quantity of raster data. The second sub-protocol allows the recipient of the data to dictate the order in which various types of data are transmitted, while allowing for efficient error correction of lost and/or corrupted packets. The protocol minimizes handshaking by sending a large number of data packets between acknowledgments. In addition, the present invention allows a host computer system (166) to request printer profile information (194), and process raster data based on the profile information.