Q-Andrew: a consolidated QOS management framework

Tese de mestrado em Segurança Informática, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2008As redes IP convergentes são compostas por uma diversidade de tecnologias que suportam múltiplos tipos de serviços com diferentes características. Cada fabricante de equipamento activo de rede usa sistemas de manutenção proprietários, incompatíveis com equipamentos de outros fabricantes. Para um operador de telecomunicações a gestão da Qualidade de Serviço, numa rede composta por vários fabricantes, é uma tarefa complexa e dispendiosa. Algumas tarefas requerem configuração manual para garantir a compatibilidade entre configurações de equipamentos de fabricantes diferentes. Melhorar a resposta operacional e reduzir os custos de operação nestas circunstâncias é apenas possível com a consolidação da gestão de rede. Para responder a este desafio, propomos: Um conjunto de mecanismos geradores de configurações de Qualidade de Serviço, consistentes entre equipamentos de diversos fabricantes; A definição de um modelo abstracto de representação destas configurações, reutilizável em futuras aproximações de gestão consolidada de rede; Por fim, descrevemos uma aplicação de demonstração onde algumas das propostas apresentadas são concretizadas, tendo como objectivo futuro a sua utilização numa rede real de um operador de telecomunicações nacional, onde são utilizados equipamentos de diversos fabricantes.Converged IP networks consist of diverse technologies and support both legacy and emerging services. Different vendors use separate management systems to achieve similar goals. Manual provisioning today represents a large portion of the total effort required to manage a complex IP network. A consolidated Quality-of-Service policy is difficult to implement in heterogeneous networks. Creating and maintaining such policies is very demanding in terms of operations. For this reason, reducing operational costs while improving Quality-of-Service Management is only possible through a consolidated approach to network management. To leverage operations in converged IP networks, we propose the following: A mechanism to automatically generate consistent configurations across a network with equipment from different vendors; A framework definition such that network element configurations can be specified using a common model; Applying some of the methods proposed to an application that can be used in a real network with diverse technologies and equipment vendors

Traffic Management Algorithms in Differentiated Services Networks

The Differentiated Services (DiffServ) Architecture, a Quality of Service (QoS) solution being worked on by an IETF work group, is aimed to solve the increasing problems with no service guarantees in the current Internet. New services such as video-on-demand and IP-telephony will be unusable without some sort of service guarantees on which to build applications on. A replacement architecture for the Integrated Services (IntServ) Architecture is needed because of its problems with overhead and scalability. This master thesis studies and evaluates traffic algorithms, specifically scheduling and active queue management algorithms, within the Differentiated Services area using the Network Simulator. The studies investigate Differentiated Services network stability and performance through noise influenced simulations. Results show that against unresponsive users network stability and performance mainly depends on the used scheduling algorithm

QoS in Today's Internet

To be able to guarantee service quality end-to-end Quality of Service has to be deployed. This thesis addresses the problems with applying QoS end-to-end over today’s Internet. A rather pessimistic conclusion states that QoS over Internet is hard (impossible?) to realize without introducing virtual circuits or similar. The concept of flows and label switching is introduced. Some QoS techniques are presented

Performance evaluation of multicast networks and service differentiation mechanisms in IP networks

The performance of a communication network depends on how well the network is designed in terms of delivering the level of service required by a given type of traffic. The field of teletraffic theory is concerned with quantifying the three-way relationship between the network, its level of service and the traffic arriving at the network. In this thesis, we study three different problems concerning this three-way relationship and present models to assist in designing and dimensioning networks to satisfy the different quality of service demands. In the first part of the thesis, we consider service differentiation mechanisms in packet-switched IP networks implementing a Differentiated Services (DiffServ) architecture. We study how bandwidth can be divided in a weighted fair manner between persistent elastic TCP flows, and between these TCP flows and streaming real-time UDP flows. To this end, we model the traffic conditioning and scheduling mechanisms on the packet and the flow level. We also model the interaction of these DiffServ mechanisms with the TCP congestion control mechanism and present closed-loop models for the sending rate of a TCP flow that reacts to congestion signals from the network. In the second part, we concentrate on non-persistent elastic TCP traffic in IP networks and study how flows can be differentiated in terms of mean delay by giving priority to flows based on their age. We study Multi Level Processor Sharing (MLPS) disciplines, where jobs are classified into levels based on their age or attained service. Between levels, a strict priority discipline is applied; the level containing the youngest jobs has the highest priority. Inside a particular level, any scheduling discipline could be used. We present an implementation proposal of a two-level discipline, PS+PS, with the Processor Sharing discipline used inside both levels. We prove that, as long as the hazard rate of the job-size distribution is decreasing, which is the case for Internet traffic, PS+PS, and any MLPS discipline that favors young jobs, is better than PS with respect to overall mean delay. In the final part, we study distribution-type streaming traffic in a multicast network, where there is, at most, one copy of each channel transmission in each network link, and quantify the blocking probability. We derive an exact blocking probability algorithm for multicast traffic in a tree network based on the convolution and truncation algorithm for unicast traffic. We present a new convolution operation, the OR-convolution, to suit the transmission principle of multicast traffic, and a new truncation operator to take into account the case of having both unicast and multicast traffic in the network. We also consider different user models derived from the single-user model.reviewe

Implementation of parametric models dependent on instantneous values of network traffic in OPNET Modeler simulation environment

Cílem diplomové práce je vytvoření modelu DiffServ domény, doplněné o stanice generující síťový provoz různého charakteru a následná implementace mechanismu token-bucket v procesním modelu směrovače v simulačním programu Opnet Modeler. DiffServ doména se skládá ze dvou hraničních a dvou vnitřních směrovačů a obsahuje klientské stanice a servery, generující provoz VoIP, FTP, HTTP a přístup do databáze. Je popsán postup rozdělení provozu do různých tříd na hraničních směrovačích DiffServ domény a zajištění odlišného způsobu zacházení s využitím mechanismu Assured Forwarding PHB. Na místě, kde dochází k diferencovanému zpracování paketů, je procesní model doplněn o generování různých statistik. Postup jejich vytvoření je využitý při ověření činnosti zahazovače, který je implementován spolu s mechanismem token-bucket na ARP vrstvě směrovače. Ověření funkčnosti modelu je provedeno simulací.The aim of this diploma thesis was to create an own DiffServ domain model, which is supplemented with stations generating various type of network traffic and implementation of token-bucket mechanism in router´s process model in Opnet Modeler simulation environment. DiffServ domain is made up from two edge and two core routers and includes servers and client stations generating VoIP, FTP, HTTP and database access traffic. It is described a process of distribution of traffic into different classes on edge routers of DiffServ domain along with assurance of separate handling with usage of an Assured Forwarding PHB mechanism. In point of differentiated packet processing is process model completed with generating of various statistics. The process of their creating is used to check a dropper activity, which is implemented together with token-bucket mechanism on ARP layer of the router. The functionality of the model is verified by simulation.