1,501 research outputs found
OSI-compatible protocols for mobile-satellite communications: The AMSS experience
The protocol structure of the international aeronautical mobile satellite service (AMSS) is reviewed with emphasis on those aspects of protocol performance, validation, and conformance which are peculiar to mobile services. This is in part an analysis of what can be learned from the AMSS experience with protocols which is relevant to the design of other mobile satellite data networks, e.g., land mobile
Report on the Standardization Project ``Formal Methods in Conformance Testing''
This paper presents the latest developments in the “Formal Methods in Conformance
Testing” (FMCT) project of ISO and ITU–T. The project has been initiated to study
the role of formal description techniques in the conformance testing process. The goal
is to develop a standard that defines the meaning of conformance in the context of formal
description techniques. We give an account of the current status of FMCT in the
standardization process as well as an overview of the technical status of the proposed
standard. Moreover, we indicate some of its strong and weak points, and we give some
directions for future work on FMCT
Formal Specification and Testing of a Management Architecture
The importance of network and distributed systems management to supply and maintain services required by users has led to a demand for management facilities. Open network management is assisted by representing the system resources to be managed as objects, and providing standard services and protocols for interrogating and manipulating these objects. This paper examines the application of formal description techniques to the specification of managed objects by presenting a case study in the specification and testing of a management architecture. We describe a formal specification of a management architecture suitable for scheduling and distributing services across nodes in a distributed system. In addition, we show how formal specifications can be used to generate conformance tests for the management architecture
The battle between standards: TCP/IP vs OSI victory through path dependency or by quality?
Between the end of the 1970s and 1994 a fierce competition existed between two possible standards, TCP/IP and OSI, to solve the problem of interoperability of computer networks. Around 1994 it became evident that TCP/IP and not OSI had become the dominant standard. We specifically deal with the question whether the current dominance of the TCP/IP standard is the result of third degree path dependency or of choices based on assessments of it being technical-economically superior to the OSI standard and protocols
Literature Review Of OSI Protocols For Distributed Interactive Simulation: Part 2
Report documenting the results of a literature search performed to examine the relationship between Open Systems Interconnection (OSI) protocols and distributed interactive simulation (DIS)
Ensuring interoperability between network elements in next generation networks
Next Generation Networks (NGNs), based on the Internet Protocol (IP), implement
several services such as IP-based telephony and are beginning to replace the classic telephony
systems. Due to the development and implementation of new powerful services
these systems are becoming increasingly complex.
Implementing these new services (typically software-based network elements) is often
accompanied by unexpected and erratic behaviours which can manifest as interoperability
problems. The reason for this caused by insufficient testing at the developing
companies. The testing of such products is by nature a costly and time-consuming
exercise and therefore cut down to what is considered the maximum acceptable level.
Ensuring the interoperability between network elements is a known challenge. However,
there exists no concept of which testing methods should be utilised to achieve an
acceptable level of quality. The objective of this thesis was to improve the interoperability
between network elements in NGNs by creating a testing scheme comprising of
three diverse testing methods: conformance testing, interoperability testing and posthoc
analysis.
In the first project a novel conformance testing methodology for developing sets of conformance
test cases for service specifications in NGNs was proposed. This methodology significantly improves the chance of interoperability and provides a considerable enhancement to the currently used interoperability tests. It was evaluated by successfully
applying it to the Presence Service.
The second report proposed a post-hoc methodology which enables the identification
of the ultimate causes for interoperability problems in a NGN in daily operation. The
new methods were implemented in the tool IMPACT (IP-Based Multi Protocol Posthoc
Analyzer and Conformance Tester), which stores all exchanged messages between
network elements in a database. Using SQL queries, the causes for errors can be found
efficiently.
Overall the presented testing scheme improves significantly the chance that network
elements interoperate successfully by providing new methods. Beyond that, the quality
of the software product is raised by mapping these methods to phases in a process model
and providing well defined steps on which test method is the best suited at a certain
stage
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