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

Master thesis deals with the design of network topologies with multiple redundant links for investor’s local area network. The objective of the thesis is to design more topology proposals according to investor’s requirements and applied technologies. Design is based on an analysis of the current state, which describes current topology of investor’s network. The main part of the thesis proposes a solution based on currently available network redundancy protocols. The functionality of the proposed solutions is tested in laboratory conditions. Finally, the individual variants are compared and their individual benefits evaluated.

The diploma thesis is focused on the basic properties of network protocols. The main task is to create laboratory tasks that deal with the basic features of network protocols and communication techniques, along with detailed instructions for students of communication technologies. The theoretical part of thesis acquaints the reader with the topic of computer networks and the basic network protocols of the TCP/IP architecture, which occur within the created lab. The practical part contains a selection of testing environment and subsequent description of installation and preparation of selected GNS3 environment. Finally are presented labs, which have been created. First lab deals with the basic differences between TCP and UDP. The second lab is focused on the issue of multicast and the third deals with the basics of penetration testing.

In this paper, we introduce a clean-slate architecture for improving the delivery of data packets in IEEE 802.11 wireless mesh networks. Opposed to the rigid TCP/IP layer architecture which exhibits serious deficiencies in such networks, we propose a unitary layer approach that combines both routing and transport functionalities in a single layer. The new Mesh Transmission Layer (MTL) incorporates cross-interacting routing and transport modules for a reliable data delivery based on the loss probabilities of wireless links. Due to the significant drawbacks of standard TCP over IEEE 802.11, we particularly focus on the transport module, proposing a pure rate-based approach for transmitting data packets according to the current contention in the network. By considering the IEEE 802.11 spatial reuse constraint and employing a novel acknowledgment scheme, the new transport module improves both goodput and fairness in wireless mesh networks. In a comparative performance study, we show that MTL achieves up to 48% more goodput and up to 100% less packet drops than TCP/IP, while maintaining excellent fairness results.

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No description available.

This thesis describes the Flexible Internetwork Stack (FINS) Framework, an open-source tool to facilitate experimental research in wireless networks on multiple platforms. The FINS Framework uses a module-based architecture that allows cross-layer behavior and runtime reconfiguration of the protocol stack. Version 1.0 of the framework makes use of existing physical and data link layer functionality, while enabling modifications to the stack at the network layer and above, or even the implementation of a clean-slate, non-layered protocol architecture. Protocols, stubs for communicating with intact layers, and management and supervisory functions are implemented as FINS Framework modules, interconnected by a central switch. This thesis describes the FINS Framework architecture, presents an initial assessment along with experiments on Android and Ubuntu enabled by the tool, and documents an intuitive mechanism for transparently intercepting socket calls that maintains efficiency and flexibility. / Master of Science

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