Security protocols require more rigorous and of logic and belief. Through an idealized form and employing detailed verification than normal communication protocols logical rules at each step of the protocol, we infer some beliefs before their deployment because even a trivial flaw in their (after application of postulates) which show agreement or architecture may produce drastic results. These verification disagreement with the initial protocol specification. This procedures are based upon the abstract formal methods group consists largely on BAN logic [2] and its variants like producing analytical rules to show if a given protocol is secure or GNY logic, Higher Order Logic (HOL) theory, SvO logic not. The technical difficulties to master formal techniques by GNY , VOlogics) tc. non-mathematicians have given rise to online validation tools (combination of BNa & GNY, VO logics) etco.which are easy to use and produce a human readable output. Second group [3] can be referred as Proof-constructionThese online tools differ in many parameters. Our work is aimed methods a protocol is defined on the bases of reliable and to present a qualitative comparison of two automatic security unreliable principles. Precise roles of each participant and protocol analysers Hermes and AVISPA for the some pertinent their beliefs are clearly separated. Then, theorems are proved parameters.to prove or disprove secrecy of a protocol specification.Generally, at the end, human-readable results are produced.

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GSI 46, rue Barrault 75634 Paris Cedex 13 FRANCE FRANCE 25, boulevard de l'Amiral Bruk 75782 Paris Cedex 16ARSTRACT The purpose of this paper is to study the general concept of Quality of Service (QOS) and to propose a QOS framework. QOS is commonly viewed as one of the important issues in Broadband Integrated Services Digital Network (B-ISDN). It is a critical factor in this future network that will support a wide variety of services ranging from voice and data to, ultimately, multimedia services. These services will cause tremendous competition among network and service providers. We overview the user's requirements and the concept of QOS, and then propose a framework for QOS. We assume three types of intercommunicating entities in this framework : network provider, service provider, and final service user. The relationship between our QOS framework and the Network Management framework is described.

The paper studies the Quality of Service (QoS) concept in Broadband ISDN (B-ISDN). The QoS parameters in the ATM layer and the AAL (ATM Adaptation Layer) are defined. The main goal of this paper is to present the translation of QoS parameters between layers. We concentrate on the translation from the AAL to the ATM layer because the AAL must be designed to be service dependent and specific. The QoS parameters at the ATM layer resulting from the translation will be the performance requirements on a connection basis for the ATM network. Finally, we discuss the impacts of QoS parameter translation on guaranteeing QoS in the ATM network. 1: IntroductionAs telecommunication and computer communication evolve into high bandwidth and low delay communication, applications which were previously restricted to specialised networks can be integrated into a broadband network. The B-ISDN will be based on the Asynchronous Transfer Mode (ATM). ATM is a very flexible transfer mode which does not impose a fixed rate of transmission to the sources of information, therefore being adequate to support any type of service, either at a constant or variable bit rate. This ensures that ATM can be used not only for existing services but also for new services and applications [1] [2].A major problem, however, in the B-ISDN is how to guarantee the QoS to each service, especially given the wide range of services that the B-ISDN will be supporting and the higher degree of ATM resource sharing as compared to the conventional synchronous transfer mode (STM). To provide QoS guarantees requires at the one end the knowledge of QoS requirements, and at the other end the construction of an ATM core network that can guarantee this QoS :1) First problem is that little is known about the ATM performance requirements of future B-ISDN services, especially multi-media applications. Even the requirements of foreseeable B-ISDN services (i.e., N-ISDN services) have not been thoroughly analysed in terms of ATM network performance parameters; only ?This work was partially supported by the EEC research project M * c E (QOSMIC).Also a member of the research staff at KOREA TELECOM. some (not exact) definitions [3][4] are known. This is because the performance requirements depend not only on the diverse QoS requirements from user, but also on the layer processing and workload in host systems. So, in order to guarantee1 QoS to the user, it is necessary to introduce a set of DOS Dara meters whose properties indicate the nature and the requirements in layered protocol stack. These QoS parameters are defmed for each layer such that each layer can guarantee the demanded QoS to its next-higher layer and demands a possibly different QoS from its next-lower layer [5]. So, it is important to translate2 user requirements into ATM layer QoS parameters. We call this mechanism 00s parameter mnslation.We concentrate on the translation from the AAL to the ATM layer, as the AAL is designed to be service dependent and specific. The ATM layer QoS parameters are basically the end-to-e...

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