Showing papers on "Communications protocol published in 1978"

General technique for communications protocol validation

Abstract: A technique for the validation of protocols in communications systems is described. It can be used for systems composed of processes that can be modeled as finite directed graphs. The validation exhaustively exercises the interaction domain of a system and identifies all occurrences of a number of well-defined error conditions. The method can detect when individual processes have no predefined response to incoming messages, as well as system deadlocks and potential loss of messages due to overflow conditions.

Automated validation of a communications protocol: the CCITT X.21 recommendation

Abstract: The call establishment procedure of the X.21 interface recommended by the International Telegraph and Telephone Consultative Committee (CCITT) has been validated as a test of a recently developed theory and of an implemented system for automated communications protocol validation. The test demonstrated the applicability of the validation technique and identified a number of points where the interface state diagram does not completely define the interface behavior.

An Automated Technique of Communications Protocol Validation

Abstract: An interaction between two communicating processes can be defined in terms of a protocol or set of rules governing the exchange of messages between them. For any given protocol, it is a significant problem to determine whether or not errors can occur when the processes interact. In this paper, we describe an implementation of a recent theory of Zafiropulo, which defines protocols in terms of the interaction between two directed graphs, and uses set theory and predicate logic to determine all error conditions that can arise. The overall structure of the theory is used, but the determination of the error conditions is based on a graphical representation of the interaction, and particular emphasis is placed on the state of the channel between the two processes. The technique is currently limited to the validation of two-process protocols in which the processes return to an initial state after a finite number Of interaction steps. The implementation demonstrates that a completely automated procedure can be defined which finds a significant class of errors in communications protocols.

Protocol Validation by Duologue-Matrix Analysis

Abstract: A protocol is a set of rules which governs the interaction between processes. It is difficult to design protocols without errors because there are usually more interactions possible than anticipated. We are concerned with two-process protocols. A technique is described which identifies design errors in protocols. The technique is based on modeling a protocol as a pair of interacting graphs whereby interaction sequences are represented by path pairs (one path in each graph). The technique is currently limited to protocols that must revert to an initial or quiescent state after a finite number of interaction steps. The work represents a theory that can be automated on a digital computer.

Principles of protocol design

Abstract: This book introduces the reader to the principles used in a broad selection of modern data communication protocols and basic algorithms for use in distributed applications, including not only simple point-to-point data transfer protocols but also multi-party protocols and protocols for ensuring data security. The presentation uses CSP notation to give a concise description of the protocols considered and to provide a basis for analysis of their properties. Relating theory to practice, with a strong focus on currently important Internet protocols, the book clearly explains how the principles are exploited in real-life protocol designs. Principles of Protocol Design is aimed at third-year students and graduates who are studying computer networks/distributed systems or data communications, as well as professional system designers who are looking for the broad view of the area.

A formal approach to the desin and implementation of network communication protocol

Abstract: This paper presents a formal model using the context-free grammar (CFG) for the design and implementation of communication protocols. It is similar to the Backus-Naur Form that has been used to define the syntax of programming languages. The transmission grammar (TG) is used to define the protocol for the communication entities of a computer network. For the hierarchical protocol design, the communication entity of each level is decomposed into more detailed inner-layered components and/or logically independent parts. The local approach is first used to define the TG for each of the decomposed components and logical parts. The shuffle and substitution operations are then applied to integrate the TGs of the logical parts and the TGs of the components, respectively. Examples are given to illustrate the grammatical properties of protocols and the design methodologies of TGs.

Digital data communication device

Abstract: A data communication bus structure where all module-to-module control information is grouped into two sets of lines, defined as sub-buses, wherein signal contents of the sub-buses change only at well-defined times, under the control of two other lines which themselves simply govern the transfer of control information relative to the communication. The bus structure is symmetrical with one type of each line driven by each of the two modules involved in the communication. Arbitrary standard error detecting/correcting encodings may be used on the bus to overcome possible bus failures with no change to the basic bus communications protocol.