165 research outputs found

    Reliability Models of SRP Rings

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    In this paper the all-terminal reliability and the two-terminal reliability models of rings using the Spatial Reuse Protocol (SRP) are developed. Moreover the interconnection of SRP-rings is considered

    Novel algorithms for fair bandwidth sharing on counter rotating rings

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    Rings are often preferred technology for networks as ring networks can virtually create fully connected mesh networks efficiently and they are also easy to manage. However, providing fair service to all the stations on the ring is not always easy to achieve. In order to capitalize on the advantages of ring networks, new buffer insertion techniques, such as Spatial Reuse Protocol (SRP), were introduced in early 2000s. As a result, a new standard known as IEEE 802.17 Resilient Packet Ring was defined in 2004 by the IEEE Resilient Packet Ring (RPR) Working Group. Since then two addenda have been introduced; namely, IEEE 802.17a and IEEE 802.17b in 2006 and 2010, respectively. During this standardization process, weighted fairness and queue management schemes were proposed to be used in the standard. As shown in this dissertation, these schemes can be applied to solve the fairness issues noted widely in the research community as radical changes are not practical to introduce within the context of a standard. In this dissertation, the weighted fairness aspects of IEEE 802.17 RPR (in the aggressive mode of operation) are studied; various properties are demonstrated and observed via network simulations, and additional improvements are suggested. These aspects have not been well studied until now, and can be used to alleviate some of the issues observed in the fairness algorithm under some scenarios. Also, this dissertation focuses on the RPR Medium Access Control (MAC) Client implementation of the IEEE 802.17 RPR MAC in the aggressive mode of operation and introduces a new active queue management scheme for ring networks that achieves higher overall utilization of the ring bandwidth with simpler and less expensive implementation than the generic implementation provided in the standard. The two schemes introduced in this dissertation provide performance comparable to the per destination queuing implementation, which yields the best achievable performance at the expense of the cost of implementation. In addition, till now the requirements for sizing secondary transit queue of IEEE 802.17 RPR stations (in the aggressive mode of operation) have not been properly investigated. The analysis and suggested improvements presented in this dissertation are then supported by performance evaluation results and theoretical calculations. Last, but not least, the impact of using different capacity links on the same ring has not been investigated before from the ring utilization and fairness points of view. This dissertation also investigates utilizing different capacity links in RPR and proposes a mechanism to support the same

    Aikakriittisen Ethernet-verkon toteuttaminen hyödyntäen Time-Sensitive Networking -tekniikkaa

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    Tämän kandidaatintyön tarkoituksena on tutkia Time-Sensitive Networking (TSN) -tekniikkaa sekä sitä edeltänyttä Audio Video Bridging (AVB) -tekniikkaa. TSN on joukko IEEE:n 802 Ethernet alastandardeja, jotka mahdollistavat aikakriittisen tietoliikenteen siirtämisen tavallisessa Ethernet-verkossa. Työssä ei käsitellä aivan kaikkia TSN:n standardeja, vaan TSN:n toiminnan kannalta oleellisimmat standardit. Myös TSN:ää edeltänyt AVB käsitellään lyhyesti, koska jotkin TSN:n standardit pohjautuvat AVB:n standardeihin. TSN:n standardeihin perehtymisen lisäksi työssä käydään läpi, mitä TSN:n standardeja tukevia laitteita markkinoilla on jo olemassa tämän työn kirjoittamisen aikana. Viimeisenä osana työtä esitellään työssä toteutettu kokeellinen toteutus, jonka tarkoituksena oli demonstroida TSN:n toimintaa tietoverkossa, joka koostui kahdesta päätepistelaitteesta sekä kahdesta kytkimestä. Markkinoilla olevien TSN:n standardeja tukevien laitteiden löytämiseksi selvitettiin, mitkä teollisuus- ja teknologiayritykset ovat mukana TSN:n kehittämisessä. Tämän tiedon perusteella yrityksien tuotevalikoimia käytiin yksitellen läpi samalla karsien joukosta pois kaikki yritykset, joiden tuotevalikoimassa ei ollut TSN:ää tukevia tuotteita. TSN:n kokeellista toteutusta ei saatu kokonaisuudessaan suoritettua demonstraatiossa ilmenneen lisenssiongelman vuoksi. Työssä kuitenkin saatiin suoritettua TSN:n toiminnallisuuden konfigurointi tietoverkon kytkimiin sekä demonstroitua TSN:n aikasynkronointiominaisuus. Työssä myös osoitettiin, että olemassa olevilla laitteilla ja niiden käyttöön liittyvillä ohjeilla olisi mahdollista toteuttaa kokonainen TSN:n toiminnallisuuksia demonstroiva toteutus. Täten työtä ja sen lähteitä voidaan hyödyntää tulevaisuudessa perinpohjaisempaan TSN:n ominaisuuksien demonstroitiin

    Development of an SDN control plane for Time-Sensitive Networking (TSN) endpoints

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    Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructur

    Evaluation of on-demand routing in mobile ad hoc networks and proposal for a secure routing protocol

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    Secure routing Mobile Ad hoc Networks (MANETs) has emerged as an important MANET research area. Initial work in MANET focused mainly on the problem of providing efficient mechanisms for finding paths in very dynamic networks, without considering the security of the routing process. Because of this, a number of attacks exploit these routing vulnerabilities to manipulate MANETs. In this thesis, we performed an in-depth evaluation and performance analysis of existing MANET Routing protocols, identifying Dynamic Source Routing (DSR) as the most robust (based on throughput, latency and routing overhead) which can be secured with negligible routing efficiency trade-off. We describe security threats, specifically showing their effects on DSR. We proposed a new routing protocol, named Authenticated Source Routing for Ad hoc Networks (ASRAN) which is an out-of-band certification-based, authenticated source routing protocol with modifications to the route acquisition process of DSR to defeat all identified attacks. Simulation studies confirm that ASRAN has a good trade-off balance in reference to the addition of security and routing efficiency

    IP and ATM - current evolution for integrated services

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    Current and future applications make use of different technologies as voice, data, and video. Consequently network technologies need to support them. For many years, the ATM based Broadband-ISDN has generally been regarded as the ultimate networking technology, which can integrate voice, data, and video services. With the recent tremendous growth of the Internet and the reluctant deployment of public ATM networks, the future development of ATM seems to be less clear than it used to be. In the past IP provided (and was though to provide) only best effort services, thus, despite its world wide diffution, was not considered as a network solution for multimedia application. Currently many of the IETF working groups work on areas related to integrated services, and IP is also proposing itself as networking technology for supporting voice, data, and video services. This paper give a technical overview on the competing integrated services network solutions, such as IP, ATM and the different available and emerging technologies on how to run IP over ATM, and tries to identify their potential and shortcomings

    A Fairness Algorithm for High-speed Networks based on a Resilient Packet Ring Architecture

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    IEEE is currently standardizing a spatial reuse ring topology network called the Resilient Packet Ring (RPR, IEEE P802.17). The goal of the RPR development is to make a LAN/MAN standard, but also WANs are discussed. A ring network needs a fairness algorithm that regulates each stations access to the ring. The RPR fairness algorithm is currently being developed with mostly long distances between stations in mind. In this paper we discuss the feedback aspects of this algorithm and how it needs to be changed in order to give good performance if and when RPR is used for high-speed networks and LANs with shorter distances between stations. We discuss different architectural parameters including buffers sizes and distances between stations. We suggest the use of triggers instead of timers to meet the response requirements of high-speed networks. We have developed a discrete event simulator in the programming language Java. The proposed improvements are compared and evaluated using a ring network model that we have built using our simulator. (c) 2002 IEEE. Personal use of this material is permitted

    Supporting NAT traversal and secure communications in a protocol implementation framework

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    Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Engenharia Electrotécnica e de ComputadoresThe DOORS framework is a versatile, lightweight message-based framework developed in ANSI C++. It builds upon research experience and subsequent knowledge garnered from the use and development of CVOPS and OVOPS, two well known protocol development frameworks that have obtained widespread acceptance and use in both the Finnish industry and academia. It conceptually resides between the operating system and the application, and provides a uniform development environment shielding the developer from operating system speci c issues. It can be used for developing network services, ranging from simple socket-based systems, to protocol implementations, to CORBA-based applications and object-based gateways. Originally, DOORS was conceived as a natural extension from the OVOPS framework to support generic event-based, distributed and client-server network applications. However, DOORS since then has evolved as a platform-level middleware solution for researching the provision of converged services to both packet-based and telecommunications networks, enterprise-level integration and interoperability in future networks, as well as studying application development, multi-casting and service discovery protocols in heterogeneous IPv6 networks. In this thesis, two aspects of development work with DOORS take place. The rst is the investigation of the Network Address Translation (NAT) traversal problem to give support to applications in the DOORS framework that are residing in private IP networks to interwork with those in public IP networks. For this matter this rst part focuses on the development of a client in the DOORS framework for the Session Traversal Utilities for NAT (STUN) protocol, to be used for IP communications behind a NAT. The second aspect involves secure communications. Application protocols in communication networks are easily intercepted and need security in various layers. For this matter the second part focuses on the investigation and development of a technique in the DOORS framework to support the Transport Layer Security (TLS) protocol, giving the ability to application protocols to rely on secure transport layer services
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