Showing papers on "Internetwork protocol published in 1988"

Adaptive hybrid multiple access protocols

Abstract: A class of adaptive hybrid multiple access protocols for a single channel, time division communications network dynamically switches among contention (Aloha), reservation, and fixed assignment (TDMA) protocols as a function of the traffic on the channel. This class of protocols is referred to as "Aloha-Reservation-TDMA" or "ART" class protocols. Within the ART class, a subclass of protocols is defined for satellite communication networks. This subclass is referred to as "Adaptive Satellite Hybrid Access" or "ASHA," and two examples of protocols within the ASHA subclass are described to show the viability of the ART class protocols. These protocols are referred to as ASHA1 and ASHA2. Both the ASHA1 and ASHA2 protocols combine the features of S-ALOHA, TDMA-Reservation and TDMA protocols. The ASHA1 protocol transmits reservation information when the Aloha protocol is selected, but the ASHA2 protocol does not. An Aloha/Reservation adaptive hybrid protocol is described in which the switch from the Reservation protocol to the Aloha protocol occurs when a reservation queue has been clear for a predetermined non-zero number of time slots. A Reservation/TDMA adaptive hybrid protocol is described in which the switch between the Reservation protocol and the TDMA protocol occurs when a predetermined number of stations on the network have transmitted information packets within a window. An Aloha/TDMA adaptive hybrid protocol is also described in which the switch from the Aloha protocol to the TDMA protocol occurs when a predetermined number of information packets have collided within a window.

An analysis of TCP processing overhead

Abstract: The authors report a preliminary analysis of the processing overhead of the transport protocol TCP (Transmission Control Protocol) in which they estimate the possible performance range of the protocol. The analysis was performed by compiling a version of TCP and counting the number of the instructions in the common path. The analysis suggests that fewer than 200 instructions are required to process a TCP packet in the normal case. This number is small enough to support very high-speed transmission if it were the major overhead. The authors offer some speculations about the actual source of processing overhead in network protocols. >

Lan with interoperative multiple operational capabilities

Abstract: Two different communication protocols are interoperatively combined for use in a local area network (LAN). An enhanced protocol can be selected as an alternative to a common protocol during communication between enhanced nodes of the LAN. Signals communicated between nodes of the LAN in the first and second protocols create the appearance of valid activity in both protocols, and always communicate at least some valid information in one of the protocols and selectively communicate additional valid information in a second protocol. Preferably the signals applied in the second or enhanced protocol include signals which are inserted in such a way that they are transparent to the first protocol. Improved network management capabilities and data transfer rates are available as a result of the information communicated in the second protocol.

The OSI management architecture: an overview

Abstract: A description is given of the OSI (Open Systems Interconnection) management environment, which consists of tools and services needed to control and supervise interconnection activities and any associated managed objects. It is intended to allow a user, once he or she has been provided with the capability of communicating across several subnetworks, to manage this collection of subnetworks and systems as a single communications network. The OSI management structure is examined, and an outline of OSI management services is provided. The common management information protocol (CMIP), a general-purpose management protocol that is suitable for the management of both OSI resources and the real resources used to provide communications services, is presented. Future extensions of OSI management research are discussed. >

Bridges and routers

Abstract: An examination is made of data link bridges and internetwork routers, two technologies that provide for the extension and interconnection of local networks, which may occur using high-speed wide-area digital data communications services. The discussion of bridges covers simple bridges, learning bridges, source routing, and quality of service offered by bridges. The discussion of routers considers the Transmission Control Protocol and Internet Protocol (known as TCP/IP) used by ARPAnet, DECnet, and quality of service offered by routers. >

XTP/PE overview

Abstract: The Xpress Transfer Protocol (XTP) is a lightweight transport protocol with unified internetwork services conforming to OSI (Open Systems Interconnection) layers 3 and 4. The Protocol Engine (PE) is a chip set designed to execute XTP and other protocols in real time. The author provides an overview of both developments. The VLSI strategy is shown, and the main technical issues in configuring an XTP/PE system at 1 Gbit/sec are described. >

A fault-tolerant protocol for atomic broadcast

Abstract: A novel general protocol for atomic broadcast in networks is presented. The protocol tolerates loss, duplication, reordering, delay of messages, and network partitioning in an arbitrary network of 'fail-stop' sites (i.e. no Byzantine site behavior is tolerated). The protocol is fully decentralized and is based on majority-consensus decisions to commit on unique ordering of received broadcast messages. Under normal operating conditions, the protocol requires three phases to complete and approximately 4N messages where N is the number of sites. If more than 4N broadcast messages are exchanged in each protocol execution, this protocol achieves better performance than any of the protocols published to date without assuming specific types of site connectivity, clock synchronization, or knowledge of failed sites and failed communication links. Under abnormal operating conditions, a decentralized termination protocol, also presented, is invoked. A performance analysis of this protocol shows that it commits with high probability under realistic operating conditions without invoking termination protocol if N is sufficiently large. >

Executable logic specifications for protocol service interfaces

Abstract: A general, formal modeling technique for protocol service interfaces is discussed. An executable description of the model using a logic-programming-based language, Prolog, is presented. The specification of protocol layers consists of two parts, the specification of the protocol interfaces and the specification of entities within the protocol layer. The specification of protocol interfaces forms the standard against which protocols are verified. When a protocol has been implemented, the correctness of its implementation can be tested using the sequences of events generated at the service interface. If the behavior of the protocol implementation is consistent with the behavior at the service interface, the implementation conforms to its standard. To illustrate how it works, the model is applied to the service interfaces of protocol standards developed for the transport layer of the ISO/OSI architecture. The results indicate that Prolog is a very useful formal language for specifying protocol interfaces. >

A methodology for constructing communication protocols with multiple concurrent functions

Abstract: A methodology is presented for the construction of communication protocols which perform several distinct functions simultaneously. The construction of such a multi-function protocol consists of three steps: (1) the development of component protocols for the different functions, (2) the integration of component protocols into a merged protocol, and (3) the specification of operational relationship among the component protocols. The conditions required for the resulting merged protocol to retain the safety properties, such as freedom from unspecified receptions, freedom from deadlocks, and boundedness, of the component protocols are discussed. The methodology is simple and facilitates the reuse of existing protocols. Two examples are given to illustrate its usage: a full-duplex data transfer protocol and another data transfer protocol with pipelining and flow control.

Management of distributed measurement over interconnected networks

Abstract: A model is described for managing stand-alone network measurement devices distributed over an interconnected network (i.e. a network of networks, or internet). A host anywhere on the internet can act as a controlling device that manages a scattered set of measurement monitors. A protocol based on this model and the service it provides are discussed. The protocol fits in the application layer of the OSI model. >

An X.PC/TCP protocol translator

Abstract: The design of a computer communications device is presented the purpose of which is to act as a translator between two virtual circuit protocols: Tymnet's X.PC, and the US Department of Defense's DOD's TCP. Protocol translation in general and details on how the X.PC/TCP translation is done are discussed. Problems found in the task of protocol translation are also discussed. >

A security imbedded authentication protocol

Abstract: A authentication protocol with security imbedded into it is reported. It is based on a combination of the private-key and the public-key encryption systems. A Petri-net model of the protocol is presented to verify that the protocol is correct and deadlock-free. >

Baseband emulators for the protocol testing of multimedia communication networks

Abstract: The testing of protocols for survivable computer communications networks that use different propagation media, so that the vulnerability of any one medium is offset by the availability of another, is considered. The design and construction of a prototype testbed that can emulate the effects of a stressed medium at either a packet or bit level is discussed, with particular reference to the Multi-Media Link Emulation currently under development. The design incorporates emulation-service protocols that fit in below the user packet switch network protocol and replace the actual user physical link layer and makes use of a seven-event fault set. The components of the ultimate system and its present implementation status are described. >

Interconnecting heterogeneous networks to OSI with a global name scheme and gateway address mapping

Abstract: The ongoing development of the OSI standards for computer communication prompts existing networks to provide OSI interconnectivity. Achieving this requires two mechanisms: a global scheme to name applications, and specific solutions to provide internetwork addressability between applications. The problem of identification of remote resources across between two networks is considered. A solution is presented for the case of the interconnection of OSI and of a generic non-OSI network architecture. The OSI model is presented first, then an integration strategy is developed, both for naming and addressing. An internetwork directory service instrumental to such an integration is introduced and developed in some detail. >

Error-free high-speed data transmission protocol simultaneously applicable to both wire and mobile radio channels

Abstract: The authors describe an integrated mobile communications traffic analysis of voice, data and image by a cellular mobile telephone system. They report the results of lost-call and simulation analysis under various traffic conditions. A newly developed universal protocol, an ARQ-based protocol adapted for land data transmission, is considered, along with an forward error correction (FEC)-based protocol which is the adaptive error control protocol adopted for mobile high-speed data transmission. It is found that the integrated mobile communications service can be provided by the present analog cellular system. When used with a 4800 bit/s CCITT V.27 ter modem, this newly developed protocol increases the throughput to 120%. This new protocol can handle data transmission on burst error-prone radio channels if the bit error rate (BER) is less than about 5*10/sup -2/. >

A deterministic communication protocol for distributed real-time systems

Abstract: The authors describe an efficient communication protocol for transmitting time-constrained messages in a time-division multiple-access local area network. The proposed protocol differs from traditional protocols in this category in that it uses the bandwidth of the medium more effectively by explicitly passing the mastership between stations. In the present protocol, the drawback inherent to fixed-master protocols, viz., imposing a star topology in a multiple-access environment. is resolved, resulting in shorter response times. The proposed protocol provides for the fair passing of the mastership between stations, thus guaranteeing the same response times for all stations. The mastership-passing protocol has been implemented and extensively tested in a 2.5 Mb/s real-time network. >

Performance of window flow control scheme for interconnected packet networks

Abstract: When communication packet networks are interconnected, all internetwork traffic concentrates at the connecting point, and flow control is needed. X.75 provides window flow control at the connecting point (signaling terminal equipment). The authors investigate the performance of the window-flow-control scheme by simulation. They compare three ways of instituting flow-control-boundary division, and show that end-to-end within each network and between the two terminal is the best boundary division because its offers has satisfactory total delay with small buffer in the signaling terminal equipment. The concept and design of a service access procedure are presented for establishing transparent and reliable connections between the top three layer protocols of the ISO Open System Interconnection (OSI) and the corresponding bottom four layer protocols. The transport and network protocols have been selected to be the US Department of Defense standard transmission control protocol (IP), respectively. The upper layer protocols are made a part of the host processor's software whereas the TCP/IP and the subsequent lower layer protocols are resident in a physically distinct device such as an interface unit. >

Development of O&M communications for an intelligent network

Abstract: The development of the communication protocol software used for operations and maintenance (O&M) communications in a distributed intelligent network for initial application in British Telecom's digital derived services network (DSSN) is described. The communication protocol is based on the OSI seven-layer reference model. The intelligent network architecture is briefly described and the OSI reference model is summarized. The development strategy followed, and the experiences encountered in doing the development, are also described. >

A layered networking protocol designed to minimize complexity

Abstract: The design of a networking protocol for the use in connecting heterogeneous computer systems is presented. The design describes a protocol based on a layered philosophy and provides for a minimum cost connections between the computer system in the network. For each layer of the network the design choices used in the network protocol are presented and a simple file transfer mechanism and message passing facility are presented with their interfaces to the network.

A method for testing data aspects of protocol implementation and its applications to the OSI session layer

Abstract: A method is presented to design conformance tests especially for data. Test cases are defined in a systematic way. The method was applied to design tests for the connection phase of the OSI (Open System Interconnection) session protocol. The tests that were designed revealed bugs in implementations. >

A new multiple access protocol for active star-configured fiber-optic local area networks-STARMAP

Abstract: A multiple-access protocol called STARMAP is proposed for active star-configured fiber-optic local area networks. The main features of the protocol include collision-avoidance, no packet retransmissions, a bounded access delay time, and a reasonable degree of fairness among the nodes contending for transmission. The analysis of the protocol is based on an embedded discrete-time queuing process obtained by examining the system only at the beginning of the node transmission times. Expressions for the throughput and the mean packet delay are presented. Numerical, as well as simulation, results are obtained for a four-node system and a ten-node system. For the numerical examples considered, the STARMAP protocol seems to show superior performance over the HUBNET protocol. >

Service access procedure (SAP) for the transmission control protocol (TCP)

Abstract: The concept and design of a service access procedure (SAP) are presented for establishing transparent and reliable connections between the top three layer protocols of the ISO Open System Interconnection (OSI) and the corresponding bottom four layer protocols. The transport and network protocols have been selected to be the US Department of Defense standard transmission control protocol (TCP) and internet protocol (IP), respectively. The upper layer protocols are made a part of the host processor's software whereas the TCP/IP and the subsequent lower layer protocols are resident in a physically distinct device such as an interface unit. >