Traffic Profiles and Performance Modelling of Heterogeneous Networks

This thesis considers the analysis and study of short and long-term traffic patterns of heterogeneous networks. A large number of traffic profiles from different locations and network environments have been determined. The result of the analysis of these patterns has led to a new parameter, namely the 'application signature'. It was found that these signatures manifest themselves in various granularities over time, and are usually unique to an application, permanent virtual circuit (PVC), user or service. The differentiation of the application signatures into different categories creates a foundation for short and long-term management of networks. The thesis therefore looks from the micro and macro perspective on traffic management, covering both aspects. The long-term traffic patterns have been used to develop a novel methodology for network planning and design. As the size and complexity of interconnected systems grow steadily, usually covering different time zones, geographical and political areas, a new methodology has been developed as part of this thesis. A part of the methodology is a new overbooking mechanism, which stands in contrast to existing overbooking methods created by companies like Bell Labs. The new overbooking provides companies with cheaper network design and higher average throughput. In addition, new requirements like risk factors have been incorporated into the methodology, which lay historically outside the design process. A large network service provider has implemented the overbooking mechanism into their network planning process, enabling practical evaluation. The other aspect of the thesis looks at short-term traffic patterns, to analyse how congestion can be controlled. Reoccurring short-term traffic patterns, the application signatures, have been used for this research to develop the "packet train model" further. Through this research a new congestion control mechanism was created to investigate how the application signatures and the "extended packet train model" could be used. To validate the results, a software simulation has been written that executes the proprietary congestion mechanism and the new mechanism for comparison. Application signatures for the TCP/IP protocols have been applied in the simulation and the results are displayed and discussed in the thesis. The findings show the effects that frame relay congestion control mechanisms have on TCP/IP, where the re-sending of segments, buffer allocation, delay and throughput are compared. The results prove that application signatures can be used effectively to enhance existing congestion control mechanisms.AT&T (UK) Ltd, Englan

Validation of "triple-play" services in the access node

Mestrado em Engenharia Electrónica e TelecomunicaçõesCom o grande crescimento das comunicações fixas, as tecnologias de fornecimento de acesso à Internet, como o cabo (CATV) e o par de cobre (xDSL), têm possibilitado o fornecimento de serviços adicionais para além do típico acesso à Internet de Banda Larga (em que, desde há vários anos o serviço de televisão já existe na tecnologia de cabo). Assim sendo, e ainda devido a uma forte concorrência entre operadores de cabo e de “cobre”, o DSL Forum apresenta uma solução de arquitectura da rede de acesso e agregação que permite a migração da tradicional tecnologia ATM para Ethernet, em tecnologias baseadas em xDSL. A migração da arquitectura para uma rede baseada em Ethernet permite o fornecimento de serviços adicionais que exijam altos débitos, qualidade de serviço, transmissão de multicast, VOIP, entre outros. A presente tese apresenta os requisitos propostos pelo DSL Forum para o equipamento da rede de acesso e agregação: o nó de acesso (DSLAM), e um conjunto de testes conducentes à validação dos mesmos em laboratório, simulando uma possível rede de fornecedor de serviços. ABSTRACT: With the large growth of fixed communications, the technology that provides Internet access, such as cable (CATV) and copper (xDSL), need to enable the provision of additional services beyond the typical broadband Internet access (where, television service already exists for several years over cable technology). Thus, because of strong competition between cable and copper operators , DSL Forum presents an architecture and aggregation solution for the xDSL based access networks that allows the migration of traditional ATM technology to Ethernet. The migration of the architecture to Ethernet based network is due to the high speeds offer, and the possibility of additional services supporting quality of service, multicast transmission, VOIP, amongst others. This thesis presents the requirements proposed by the DSL Forum for the equipment of the access network and aggregation: access node (DSLAM), and their validation in a laboratory environment, simulating service provision scenarios

A report on IPv6 deployment activities and issues at Sandia National Laboratories:FY2007.

Internet Protocol version 4 (IPv4) has been a mainstay of the both the Internet and corporate networks for delivering network packets to the desired destination. However, rapid proliferation of network appliances, evolution of corporate networks, and the expanding Internet has begun to stress the limitations of the protocol. Internet Protocol version 6 (IPv6) is the replacement protocol that overcomes the constraints of IPv4. As the emerging Internet network protocol, SNL needs to prepare for its eventual deployment in international, national, customer, and local networks. Additionally, the United States Office of Management and Budget has mandated that IPv6 deployment in government network backbones occurs by 2008. This paper explores the readiness of the Sandia National Laboratories network backbone to support IPv6, the issues that must be addressed before a deployment begins, and recommends the next steps to take to comply with government mandates. The paper describes a joint work effort of the Sandia National Laboratories ASC WAN project team and members of the System Analysis & Trouble Resolution, the Communication & Network Systems, and Network System Design & Implementation Departments

Support For IP mobility and diversity in a broadband wireless access network

Broadband wireless access (BWA) network working at millimetre bands possesses the advantages of quick deployment, more flexibility, wide service coverage and cost efficiency. The range of services to be provided via the system includes broadband digital television, Internet data, telephony and videoconference. Apart from broadcast digital television, all traffic is carried in Internetworking Protocol (IP) format. Unfortunately the services of such a system are susceptible to impairment by buildings, vegetation, terrain and attenuation caused by rain, snow and sleet, etc. Accordingly the service availability and system performance can drop dramatically. In the worst case, the system will experience heavy packet loss and the services might be completely unavailable. An extended multiprotocol label switching (MPLS) network architecture is proposed in this thesis, which allows fast mobile IP access and diversity routing for traffic under fade condition. This supports nomadic access, reduced packet loss and improved service availability in BWA network during system outage. Also developed herein is a Diversity and Shadow Flow Merging Mechanism, which, besides sending a packet on its normal path, also duplicates the packet and sends it on a separate, diverted labelled path. The shadow flow merging mechanism is responsible for merging the normal flow and shadow flow together and delivering the merged packet to its destination. It is anticipated that the packet can be successfully delivered to the destination even if one path fails completely during the system outage. The protocol is tested on a general BWA network that is configured with Digital Video Broadcast (DVB) downlink and Multi-Frequency Time Division Multiplex Access (MF-TDMA) uplink equipments. The protocol’s ability of reducing packet loss and improving service availability, during the period of link failure, is verified. It is concluded that the protocol is effective in improving the service availability of BWA network.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Computer-Aided Sustainable Process Synthesis-Design and Analysis

Processyntese involverer undersøgelse af kemiske reaktioner, der er nødvendige for at producere det ønskede produkt, udvælgelse af separationsteknikker nødvendige for downstream forarbejdning, samt beslutninger om sekvensering af de involverede separationsprocesser. For en effektiv og fleksibel designtilgang, er der behov for en systematisk måde at identificere de typer af opgaver og operationer, der skal udføres, den tilsvarende design af operation-udstyr, deres konfiguration, masse-energistrømme m.v., hvilket giver et optimalt processkema. På grund af det faktum, at processynteseproblemer er af natur kombinatoriske og med flere mulige løsninger, er der blevet foreslået en forskellige metoder til at overkomme dette. Men løsningen til ethvert syntese-design problem er afhængig af søgningsområdet af alternativer og kriterierne for procesydeevne, som i de fleste tilfælde er påvirket af økonomiske faktorer. Dette arbejde fokuserer på udvikling og anvendelse af et computerstøttet platform for bæredygtig syntese-design og analyse af processkemaer ved at generere mulige alternativer, der dækker hele søgningsområdet og omfatter analyseværktøjer for bæredygtighed, LCA og økonomi. Syntesemetoden er baseret på en gruppebidragsbaseret hybridmetode, hvor kemisk processkemaer syntetiseres på samme måde som atomer eller grupper af atomer syntetiseres til dannelse af molekyler i computerstøttet molekylært design (eng: CAMD) teknikker. Byggestenene i et processkemasyntese problem er betegnet som procesgrupper, som repræsenterer en enkelt eller et sæt af enhedsoperationer, der er udvalgt på metoder baseret på termodynamiske grundlag. Disse byggesten kombineres derefter under anvendelse af regler for tilslutningsmuligheder for at generere alle de mulige processkemaalternativer. Den største fordel ved at repræsentere processkemaer med procesgrupper er, at udførelsen af hele processen kan vurderes fra bidragene fra de enkelte procestrinsgrupper mod processkemaegenskaberne (f.eks forbrugt energi). De udviklede processkemaegenskabsmodeller omfatter energiforbrug, carbon footprint, produktudvinding, produktrenhed osv. På denne måde er hele listen over mulige kemiske processkemaer hurtigt genereret, screenet og udvalgt til yderligere analyse. I det næste trin, er udformningen af de mest lovende processkemakandidater udført gennem en omvendt simulationsmetode, hvor designparametre for enhedsoperationer i processkemaet er beregnet ud fra udvalgte definitioner af procesgrupper. I næste fase analyseres det valgte design, til at identificere begrænsninger eller flaskehalse (hot-spots) ved hjælp af en omfattende analysemetode bestående af økonomiske, livscyklus og bæredygtigheds faktorer, der omsættes til procesdesignmål. I den afsluttende fase identificeres hot-spotsne, som er målrettet til den samlede procesforbedring og til at skabe innovative designs. I dette arbejde er den udviklede platform testet sammen med de tilhørende metoder og værktøjer gennem tre casestudier med relation til både kemiske og biokemiske industri med henblik på at fastslå anvendelsesmulighederne af platformen. I hvert af tilfældene er de mange alternativer og litteraturdesignene hurtigt genereret og evalueret. I alle de testede casestudier var de endelige designs, der genereres af platformen, nye og mere bæredygtige.Process synthesis involves the investigation of chemical reactions needed to produce the desired product, selection of the separation techniques needed for downstream processing, as well as taking decisions on sequencing the involved separation operations. For an effective, efficient and flexible design approach, what is needed is a systematic way to identify the types of tasks-operations that need to be performed, the corresponding design of the operation-equipment, their configuration, mass-energy flows, etc., giving an optimal flowsheet. Due to the fact that process synthesis problems are by nature combinatorial and open ended, a number of different solution approaches have been proposed. However the solution for any synthesis-design problem is dependent on the search space of alternatives and the process performance criteria which in most cases are influenced by economic factors. This work focuses on the development and application of a computer-aided framework for sustainable synthesis-design and analysis of process flowsheets by generating feasible alternatives covering the entire search space and includes analysis tools for sustainability, LCA and economics. The synthesis method is based on group contribution and a hybrid approach, where chemical process flowsheets are synthesized in the same way as atoms or groups of atoms are synthesized to form molecules in computer aided molecular design (CAMD) techniques. The building blocks in flowsheet synthesis problem are called as process-groups, which represent a single or set of unit operations that are selected by employing a thermodynamic insights based method. These building blocks are then combined using connectivity rules to generate all the feasible flowsheet alternatives. The main advantage of representing the flowsheet with process-groups is that, the performance of the entire process can be evaluated from the contributions of the individual process-groups towards the selected flowsheet property (for example, energy consumed). The developed flowsheet property models include energy consumption, carbon footprint, product recovery, product purity etc. In this way, the entire list of feasible chemical process flowsheets are quickly generated, screened and selected for further analysis. In the next stage, the design of the most promising process flowsheet candidates is performed through a reverse simulation approach, where the design parameters of the unit operations in the process flowsheet are calculated from selected process-groups definition. In the next stage the selected design is analyzed, for identifying process limitations or bottlenecks (hot-spots) using a comprehensive analysis method consisting of economic, life cycle and sustainability factors that are translated into design targets. In the final stage the identified hot-spots are targeted for overall process improvement and to generate innovative designs. In this work the developed framework along with the associated methods and tools is tested through three case studies related to both chemical and biochemical industry in order to ascertain the applicability of the framework. In each of the cases numerous alternatives of novel and designs reported by others are quickly generated and evaluated. In all the case studies tested, the final design generated by the framework was novel and more sustainable

Interworking public and private ATM networks

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (p. 125-128).by C. Brit Gould.M.Eng

A comparative study of in-band and out-of-band VOIP protocols in layer 3 and layer 2.5 environments

For more than a century the classic circuit-switched telephony in the form of PSTN (Public Service Telephone Network) has dominated the world of phone communications (Varshney et al., 2002). The alternative solution of VoIP (Voice over Internet Protocol) or Internet telephony has increased dramatically its share over the years though. Originally started among computer enthusiasts, nowadays it has become a huge research area in both the academic community as well as the industry (Karapantazis and Pavlidou, 2009). Therefore, many VoIP technologies have emerged in order to offer telephony services. However, the performance of these VoIP technologies is a key issue for the sound quality that the end-users receive. When making reference to sound quality PSTN still stands as the benchmark.Against this background, the aim of this project is to evaluate different VoIP signalling protocols in terms of their key performance metrics and the impact of security and packet transport mechanisms on them. In order to reach this aim in-band and out-of-band VoIP signalling protocols are reviewed along with the existing security techniques which protect phone calls and network protocols that relay voice over packet-switched systems. In addition, the various methods and tools that are used in order to carry out performance measurements are examined together with the open source Asterisk VoIP platform. The findings of the literature review are then used in order to design and implement a novel experimental framework which is employed for the evaluation of the in-band and out-of-band VoIP signalling protocols in respect to their key performance networks. The major issue of this framework though is the lack of fine-grained clock synchronisation which is required in order to achieve ultra precise measurements. However, valid results are still extracted. These results show that in-band signalling protocols are highly optimised for VoIP telephony and outperform out-of-band signalling protocols in certain key areas. Furthermore, the use of VoIP specific security mechanisms introduces just a minor overhead whereas the use of Layer 2.5 protocols against the Layer 3 routing protocols does not improve the performance of the VoIP signalling protocols

Quality-of-service management in IP networks

Quality of Service (QoS) in Internet Protocol (IF) Networks has been the subject of active research over the past two decades. Integrated Services (IntServ) and Differentiated Services (DiffServ) QoS architectures have emerged as proposed standards for resource allocation in IF Networks. These two QoS architectures support the need for multiple traffic queuing systems to allow for resource partitioning for heterogeneous applications making use of the networks. There have been a number of specifications or proposals for the number of traffic queuing classes (Class of Service (CoS)) that will support integrated services in IF Networks, but none has provided verification in the form of analytical or empirical investigation to prove that its specification or proposal will be optimum. Despite the existence of the two standard QoS architectures and the large volume of research work that has been carried out on IF QoS, its deployment still remains elusive in the Internet. This is not unconnected with the complexities associated with some aspects of the standard QoS architectures. [Continues.

Sistemas de videoconferencia sobre redes RDSI, ATM, Ethernet/IP, Frame Relay y redes celulares móviles

Enmarcada entre los servicios de las comunicaciones multimedia, la videoconferencia es un servicio digital de telecomunicaciones multimedia para el intercambio de información audiovisual entre dos o más sitios geográficamente distantes, mediante la transmisión y recepción bidireccional simultánea de audio, video datos de los participantes. Los desarrollos que ha sufrido la videoconferencia han permitido un uso muy sencillo y una fiabilidad en las comunicaciones sobre cualquier infraestructura de red. Tal es así, que estas comunicaciones pueden desarrollarse tanto sobre RDSI como sobre redes ATM, Ethernet, Frame Relay e incluso redes móviles. Sin embargo, para poder implementar un sistema de videoconferencia en una determinada red con los requisitos mínimos que esta exige, es necesario un estudio anticipado de todos los parámetros y recomendaciones a tener en cuenta para su correcto funcionamiento.Incluye bibliografí