Over the past few years, much experience has been gained in semi-automatic protocol implementation using an existing Estelle-C compiler developed at the University of British Columbia. However, with the continual evolution of the Estelle language, that compiler is now obsolete. The present study found substantial syntactic and semantic differences between the Estelle language as implemented by the existing compiler and that specified in the latest ISO document to warrant the construction of a new Estelle-C compiler. The result is a new compiler which translates Estelle as defined in the second version of the ISO Draft Proposal 9074 into the programming language C. The new Estelle-C compiler addresses issues such as dynamic reconfiguration of modules and maintenance of priority relationships among nested modules. A run-time environment capable of supporting the new Estelle features is also presented. The implementation strategy used in the new Estelle-C compiler is illustrated by using the alternating bit protocol found in the ISO Draft Proposal 9074 document. / Science, Faculty of / Computer Science, Department of / Graduate

Multiaccess protocols for integrated voice and data transmissions over satellite channels are studied, based on the SENET(slotted envelope network) structure. The satellite system is characterized as a wide band system with a large number of geographically distributed small voice and data users. Performance evaluations of commonly used protocols, i.e., ALOHA and reservation protocols, are first conducted, both analytically and by simulations. The effect of different voice backgrounds on data access protocols are shown explicitly. Based on these results, a control algorithm is proposed. Analyses and simulations show that ALOHA protocol incorporated with such a control mechanism is globally stable under the integrated environment; moreover, the performance deterioration due to voice backgrounds is dramatically reduced. The actual implementation aspects of the control algorithm are considered. An extension of the above results leads to a combined random/reservation protocol. Simulation and analysis results show that the combined protocol exhibits desired low delay and high throughput performance characteristics, with satisfactory voice blocking probability, under the worst user population assumption, i.e., all the voice sources and data sources are independent of each other — reflecting the nature of small earth station environment. The absence of the need for mini-slot structure lends ease and simplicity to the implementation of the combined protocol. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

One of the basic requirements of communication protocols in a heterogeneous computer network is a standard external data-transfer representation. Abstract Syntax Notation One (ASN.1) has been widely used in international standard specifications. Its transfer-syntax of Basic Encoding Rules (BER) is applied as the standard external data representation. This thesis presents an efficient BER implementation, called the ED library. The ED library includes a number of encoding and decoding routines that may be used as primitive functions to compose encoders and decoders for arbitrarily complicated ASN.1 data-types. The Performance of the ED library is measured and discussed. Based on the ED library, an ASN.1-C compiler, called CASN1, is designed and implemented to release communication software programmers from the arduous work of translating protocol-defined data-types and constructing their encoders and decoders. Given an ASN.1 protocol specification, CASN1 automatically translates the input ASN.1 modules into C and generates the BER encoders and decoders for the protocol denned data-types. This thesis discusses the design principles, user interface, internal structures, and the implementation and of CASN1. Example applications are given. Both the ED library and CASN1 are implemented in C on UNIX 4.2 BSD using the YACC and LEX tools. / Science, Faculty of / Computer Science, Department of / Graduate

No description available.

No description available.

Much attention has been focused on the problem of deadlock detection in distributed databases, resulting in the publication of numerous algorithms to accomplish this function. The algorithms published to date differ greatly in many respects: timing, location, information collection, and basic approach. The emphasis of this research has been on theory and proof of correctness, rather than on practical application. Relatively few attempts have been made to implement the algorithms. The impact of the characteristics of the underlying database management system, transaction model, and communications network upon the effectiveness and performance of the proposed deadlock detection algorithms has largely been ignored. It is the intent of this study to examine more closely the interaction between a deadlock detection algorithm and one aspect of the environment in which it is implemented: namely, the communications network. / Master of Science

This thesis proposes a new media access protocol for local area and metropolitan area all-optical networks employing wavelength division multiplexing (WDM). Through WDM, multiple channels are created on a single fiber, and an aggregate network bandwidth far greater than the peak electronic processing speed can be realized. The new protocol, Dynamic Media Access Control Scheme (DMACS), is based on the Dynamic Interleaved Slotted Aloha (DISA) protocol. It improves on DISA by adding a common control channel that provides reservations for constant bit-rate traffic, acknowledgments, and global flow control. DMACS supports connection setup and tear down, different traffic classes, flow control, and packet resequencing in an attempt to integrate features of the transport layer directly into the media access control layer. The performance of the DMACS protocol has been evaluated through analytical methods and simulation. It was found to be superior to the DISA protocol and to provide good performance that is relatively insensitive to the number of stations and the traffic conditions in the network. / Master of Science

Network architectures are described by the International Standard for Organization (ISO), which contains seven layers. The internet uses four of these layers, of which three are of interest to us. These layers are Internet Protocol (IP) or Network Layer, Transport Layer and Application Layer. We need to protect against attacks that may come through any of these layers. In the world of network security, systems are plagued by various attacks, internal and external, and could result in Denial of Service (DoS) and/or other damaging effects. Such attacks and loss of service can be devastating for the users of the system. The implementation of security devices such as Firewalls and Intrusion Detection Systems (IDS), the protection of network traffic with Virtual Private Networks (VPNs), and the use of secure protocols for the layers are important to enhance the security at each of these layers.We have done a survey of the existing network security patterns and we have written the missing patterns. We have developed security patterns for abstract IDS, Behavior–based IDS and Rule-based IDS and as well as for Internet Protocol Security (IPSec) and Transport Layer Security (TLS) protocols. We have also identified the need for a VPN pattern and have developed security patterns for abstract VPN, an IPSec VPN and a TLS VPN. We also evaluated these patterns with respect to some aspects to simplify their application by system designers. We have tried to unify the security of the network layers using security patterns by tying in security patterns for network transmission, network protocols and network boundary devices. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Among the plethora of solutions to the Business-to-Business interoperability problem, no other solution has obtained as much attention asWeb Services Technology (WST), which allows entities to exchange data regardless of their underlying platforms. WST also allows services to be composed in order to provide high quality customer service over the web. In order to perform transactions across different service providers, standard protocols need to be supported by participating providers. Many useful protocols are coming into the market, but are often ambiguously specified by protocol designers and not fully verified. Furthermore, even if the specifications are reasonably clear, programmers often make subtle assumptions, possibly leading to errors that are hard to detect and locate, especially when the number of participating entities is dynamic. Consequently, these can lead to interoperability problems among implementations of the same protocol and high software maintenance costs. To address these issues, a hierarchical automata-based framework is proposed to model the functional aspects of Web Services (WS) protocols that also assists in verifying their correctness. The modelling formalism has a sound mathematical foundation and aims to reconcile desirable features while still maintaining syntactic and semantic simplicity. The properties to be verified are specified using a pattern system and/or 'observer' states, which have been adapted for WS protocols. In particular, always in a positive observer state implies proper termination and partial functional correctness while reachability of a negative observer state signifies deadlock and/or violation of a safety property. Verification itself is handled by automatic translation of the model and its properties into a model-checker's input code and interpretation of the output produced by the model-checker. A test-bed is proposed to check the conformance of a protocol implementation to its specification It helps in locating errors in the implementations of WS protocols especially where the number of participating entities is dynamic. Conformance checking is achieved by capturing sequences of exchanged messages of the actual implementations and checking them against the formal specification. Experience using the framework is also described and illustrated using two non-trivial WS protocols, namely WS-BusinessActivity and WS-AtomicTransaction.

Among the plethora of solutions to the Business-to-Business interoperability problem, no other solution has obtained as much attention asWeb Services Technology (WST), which allows entities to exchange data regardless of their underlying platforms. WST also allows services to be composed in order to provide high quality customer service over the web. In order to perform transactions across different service providers, standard protocols need to be supported by participating providers. Many useful protocols are coming into the market, but are often ambiguously specified by protocol designers and not fully verified. Furthermore, even if the specifications are reasonably clear, programmers often make subtle assumptions, possibly leading to errors that are hard to detect and locate, especially when the number of participating entities is dynamic. Consequently, these can lead to interoperability problems among implementations of the same protocol and high software maintenance costs. To address these issues, a hierarchical automata-based framework is proposed to model the functional aspects of Web Services (WS) protocols that also assists in verifying their correctness. The modelling formalism has a sound mathematical foundation and aims to reconcile desirable features while still maintaining syntactic and semantic simplicity. The properties to be verified are specified using a pattern system and/or 'observer' states, which have been adapted for WS protocols. In particular, always in a positive observer state implies proper termination and partial functional correctness while reachability of a negative observer state signifies deadlock and/or violation of a safety property. Verification itself is handled by automatic translation of the model and its properties into a model-checker's input code and interpretation of the output produced by the model-checker. A test-bed is proposed to check the conformance of a protocol implementation to its specification It helps in locating errors in the implementations of WS protocols especially where the number of participating entities is dynamic. Conformance checking is achieved by capturing sequences of exchanged messages of the actual implementations and checking them against the formal specification. Experience using the framework is also described and illustrated using two non-trivial WS protocols, namely WS-BusinessActivity and WS-AtomicTransaction.