Open Shortest Path First (OSPF) had been recognized as a de facto standard for inter-domain Internet Protocol (IP) routing. Its hierarchical architecture and the introducing of Area Border Router (ABR) had been proved to be an effective solution to the scalability problem. However, manual selection of ABR may fail to accommodate the dynamic change in the network load and therefore lead to sub-optimal solution. There are two new schemes proposed in this thesis. One scheme is Dynamic Appointment ABR for OSPF (DAA-OSPF). Other one scheme is P-median OSPF Partition Algorithm. DAA-OSPF scheme is proposed for the dynamic appointment of ABR for OSPF. Based on observed traffic demands and knowledge on link capacities, the proposed scheme will dynamically switch to a new ABR from an old one to avoid incipient link congestion and accompanying performance degradation. In response to traffic change,the proposed approach will locate an adequate ABR for the new traffic pattern and then direct traffics to the new ABR. System performance, in terms of link utilization, throughput, and delay, is expected to benefit from the proposed scheme, as demonstrated in the simulation results. This study also contributes to the issue of stub area partitioning. According to our study, we recognize that the stub area partitioning problem can be well modeled by the P-median problem in logistics [WR99]. In this study, we extend and refine existing approaches to the P-median problem and apply them to the stub area partitioning problem. The refined P-median algorithm is capable of finding out the optical locations of P ABRs in a network such that the total cost is minimized. With the refined P-median algorithm, the proposed OSPF partitioning scheme is expected to minimize the cost of OSPF hierarchical routing, as well as the cost in subsequent packet transmission.

A diploma thesis introduces possibilities of the routing protocol OSPF, basic configurations and implementation into an autonomous system. A Theoretical part shows computer networks fundamentals and divide them into several groups according to standarts. It also include a part about addressing scheme in the Internet network and the ways how to subneted networks. A practical part consists of two project, that are create in a simulation program. The first simulates classroom, all the network devices and the computers are included. The second is an exam made for student to introduce OSPF in the autonomous system. The Exam uses new type of an extension, that allow student cooperate together by solving the exam. A summary contains all technique disposed in both simulations and a web presentation.

Made available in DSpace on 2014-06-12T17:35:33Z (GMT). No. of bitstreams: 2 arquivo2470_1.pdf: 6699219 bytes, checksum: f7ab13c2c0f61e4dfa1c822d8756767a (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / O aumento da demanda pela utilização de novos serviços de valor agregado sobre as infraestruturas de rede baseadas no protocolo IP (Internet Protocol), tais como voz e vídeo, contribui para que as operadoras de telecomunicações enfrentem um grande desafio para prover um backbone estável, escalável e otimizado, para atender satisfatoriamente essas novas expectativas de tráfego dos seus clientes. As empresas de telecomunicações buscam uma rede com uma maior disponibilidade e menor custo. A tecnologia MPLS (Multi-Protocol Label Switching) é indicada para prover evolução, otimização e flexibilidade aos backbones atuais, mostrando-se uma tecnologia emergente a ser empregada nessas redes. O novo paradigma de transporte baseado no MPLS permite as operadoras de telecomunicações construírem, sobre as infraestruturas IP, ATM (Asynchronous Transfer Mode) e Frame Relay, um conjunto de soluções criativas e flexíveis para suprir essa nova demanda de serviços. Dentre esses serviços, destacam-se a oferta de Internet e VPN (Virtual Private Network) na rede da operadora apoiada pela implementação de uma arquitetura com QoS (Quality of Service) e satisfazendo os requisitos de TE (Traffic Engineering) sobre MPLS. Esta dissertação apresenta a engenharia de tráfego aplicada a backbone IP MPLS de uma operadora de telecomunicações, com a aplicação prática do MPLS-TE (Multi-Protocol Label Switching Traffic Engineering), analisando e otimizando os recursos de transmissão com caminhos redundantes não utilizados pelo protocolo OSPF (Open Shortest Path First)

The thesis deals with simulation of routing protocols. The aim is to create a functioning model of OSPF link-state protocol in the simulation framework OMNET++. OMNET++ is a discrete simulation environment which was created to provide means to build models of various network protocols and technologies. Chapters in the first part of the thesis focuson the theoretical foundation of OSPFv2 and OSPFv3 and their differences. Important data structures, finite state automata and communication techniques are described and the information is later used to implement the model itself. The chapters in the second part deal with the implementation of the model in C++. The created model reflects the functionality of OSPF on Cisco devices.

Masivní vývoj Internetu vedl ke zvýšeným požadavkům na spolehlivou síťovou infrastrukturu. Efektivita komunikace v síti závisí na schopnosti směrovačů určit nejlepší cestu pro odesílání a přeposílání paketů ke koncovému zařízení. Jelikož OSPF v současné době představuje jeden z nejpoužívanějších směrovacích protokolů, jakýkoli přínos, který by pomohl udržet krok s rychle se měnícím prostředí Internetu, je velmi vítán. Významným omezením OSPF protokolu je, mimo jiné, absence informovanosti algoritmu pro výpočet metriky o aktuálním vytížení linky. Tato vlastnost představuje tzv. slabé místo, což má negativní vliv na výkonnost sítě. Z tohoto důvodu byla navržena nová metoda založená na dynamické adaptaci měnících se síťových podmínek a alternativní strategii OSPF metrik. Navržená metoda řeší problém neinformovanosti OSPF metriky o síťovém provozu a nevhodně vytížených linek, které snižují výkonnost sítě. Práce rovněž přináší praktickou realizaci, kdy vlastnosti nové metody jsou testovány a ověřeny spuštěním testů algoritmu v reálných zařízeních.

The IP protocol suite has been initallyi designed to provide best effort reachability among the nodes of a network or an inter-network. The goal was to design a set of routing solutions that would allow routers to automatically provide end-to-end connectivity among hosts. Also, the solution was meant to recover the connectivity upon the failure of one or multiple devices supporting the service, without the need of manual, slow, and error-prone reconfigurations. In other words, the requirement was to have an Internet that "converges" on its own. Along with the "Internet Boom", network availability expectations increased, as e-business emerged and companies started to associate loss of Internet connectivity with loss of customers... and money. So, Internet Service Providers (ISPs) relied on best practice rules for the design and the configuration of their networks, in order to improve their Quality of Service. The goal of this thesis is to complement the IP routing suite so as to improve its resiliency. It provides enhancements to routing protocols that reduce the IP packet losses when an IP network reacts to a change of its topology. It also provides techniques that allow ISPs to perform reconfigurations of their networks that do not lead to packet losses.

Today's society has developed a reliance on networking infrastructures. Health, financial, and many other institutions deploy mission critical and even life critical applications on local networks and the global Internet. The security of this infrastructure has been called into question over the last decade. In particular, the protocols directing traffic through the network have been found to be vulnerable. One such protocol is the Open Shortest Path First (OSPF) protocol. This thesis proposes a security extension to OSPF containing a decentralized certificate authentication scheme (DecentCA) that eliminates the single point of failure/attack present in current OSPF security extensions. An analysis of the security of the DecentCA is performed. Furthermore, an implementation of DecentCA in the Quagga routing software suite is accomplished.

<p>Rapporten handlar om routing och då med inriktning på interna routingprotokoll i första hand.</p><p>Studien är gjord med inriktning mot operatörernas nät, där det först finns en teoridel som beskriver det olika teknologierna och protokollen.</p><p>Sedan diskuteras hur det ser ut ifrån operatörernas sida och avslutas med en slutsats hur det ser ut i verkligheten idag..</p>

Rapporten handlar om routing och då med inriktning på interna routingprotokoll i första hand. Studien är gjord med inriktning mot operatörernas nät, där det först finns en teoridel som beskriver det olika teknologierna och protokollen. Sedan diskuteras hur det ser ut ifrån operatörernas sida och avslutas med en slutsats hur det ser ut i verkligheten idag..

The aim of this thesis was to get acquainted with the technology of routing data in a computer network. Thesis described in the theoretical level properties of current and past routing protocols and their use in information systems. Based on the acquired knowledge was created a simulation model of network communication in programming environment OPNET Modeler. This model analyzes the received parameters of the current protocols and their subsequent implementation in the real transmission technology using operating system Debian Linux. Finally, the transfer parameters are discussed between the simulation model and real transfer technology.