Minimizing queueing delays in computer networks

Ph.DDOCTOR OF PHILOSOPH

Distributed control architecture for multiservice networks

The research focuses in devising decentralised and distributed control system architecture for the management of internetworking systems to provide improved service delivery and network control. The theoretical basis, results of simulation and implementation in a real-network are presented. It is demonstrated that better performance, utilisation and fairness can be achieved for network customers as well as network/service operators with a value based control system. A decentralised control system framework for analysing networked and shared resources is developed and demonstrated. This fits in with the fundamental principles of the Internet. It is demonstrated that distributed, multiple control loops can be run on shared resources and achieve proportional fairness in their allocation, without a central control. Some of the specific characteristic behaviours of the service and network layers are identified. The network and service layers are isolated such that each layer can evolve independently to fulfil their functions better. A common architecture pattern is devised to serve the different layers independently. The decision processes require no co-ordination between peers and hence improves scalability of the solution. The proposed architecture can readily fit into a clearinghouse mechanism for integration with business logic. This architecture can provide improved QoS and better revenue from both reservation-less and reservation-based networks. The limits on resource usage for different types of flows are analysed. A method that can sense and modify user utilities and support dynamic price offers is devised. An optimal control system (within the given conditions), automated provisioning, a packet scheduler to enforce the control and a measurement system etc are developed. The model can be extended to enhance the autonomicity of the computer communication networks in both client-server and P2P networks and can be introduced on the Internet in an incremental fashion. The ideas presented in the model built with the model-view-controller and electronic enterprise architecture frameworks are now independently developed elsewhere into common service delivery platforms for converged networks. Four US/EU patents were granted based on the work carried out for this thesis, for the cross-layer architecture, multi-layer scheme, measurement system and scheduler. Four conference papers were published and presented

Methods of Congestion Control for Adaptive Continuous Media

Since the first exchange of data between machines in different locations in early 1960s, computer networks have grown exponentially with millions of people now using the Internet. With this, there has also been a rapid increase in different kinds of services offered over the World Wide Web from simple e-mails to streaming video. It is generally accepted that the commonly used protocol suite TCP/IP alone is not adequate for a number of modern applications with high bandwidth and minimal delay requirements. Many technologies are emerging such as IPv6, Diffserv, Intserv etc, which aim to replace the onesize-fits-all approach of the current lPv4. There is a consensus that the networks will have to be capable of multi-service and will have to isolate different classes of traffic through bandwidth partitioning such that, for example, low priority best-effort traffic does not cause delay for high priority video traffic. However, this research identifies that even within a class there may be delays or losses due to congestion and the problem will require different solutions in different classes. The focus of this research is on the requirements of the adaptive continuous media class. These are traffic flows that require a good Quality of Service but are also able to adapt to the network conditions by accepting some degradation in quality. It is potentially the most flexible traffic class and therefore, one of the most useful types for an increasing number of applications. This thesis discusses the QoS requirements of adaptive continuous media and identifies an ideal feedback based control system that would be suitable for this class. A number of current methods of congestion control have been investigated and two methods that have been shown to be successful with data traffic have been evaluated to ascertain if they could be adapted for adaptive continuous media. A novel method of control based on percentile monitoring of the queue occupancy is then proposed and developed. Simulation results demonstrate that the percentile monitoring based method is more appropriate to this type of flow. The problem of congestion control at aggregating nodes of the network hierarchy, where thousands of adaptive flows may be aggregated to a single flow, is then considered. A unique method of pricing mean and variance is developed such that each individual flow is charged fairly for its contribution to the congestion

Trade & Cap: A Customer-Managed, Market-Based System for Trading Bandwidth Allowances at a Shared Link

We propose Trade & Cap (T&C), an economics-inspired mechanism that incentivizes users to voluntarily coordinate their consumption of the bandwidth of a shared resource (e.g., a DSLAM link) so as to converge on what they perceive to be an equitable allocation, while ensuring efficient resource utilization. Under T&C, rather than acting as an arbiter, an Internet Service Provider (ISP) acts as an enforcer of what the community of rational users sharing the resource decides is a fair allocation of that resource. Our T&C mechanism proceeds in two phases. In the first, software agents acting on behalf of users engage in a strategic trading game in which each user agent selfishly chooses bandwidth slots to reserve in support of primary, interactive network usage activities. In the second phase, each user is allowed to acquire additional bandwidth slots in support of presumed open-ended need for fluid bandwidth, catering to secondary applications. The acquisition of this fluid bandwidth is subject to the remaining "buying power" of each user and by prevalent "market prices" – both of which are determined by the results of the trading phase and a desirable aggregate cap on link utilization. We present analytical results that establish the underpinnings of our T&C mechanism, including game-theoretic results pertaining to the trading phase, and pricing of fluid bandwidth allocation pertaining to the capping phase. Using real network traces, we present extensive experimental results that demonstrate the benefits of our scheme, which we also show to be practical by highlighting the salient features of an efficient implementation architecture.National Science Foundation (CCF-0820138, CSR-0720604, EFRI-0735974, CNS-0524477, and CNS-0520166); Universidad Pontificia Bolivariana and COLCIENCIAS–Instituto Colombiano para el Desarrollo de la Ciencia y la Tecnología “Francisco Jose ́ de Caldas”

The economic effects of network neutrality: a policy perspective

Network neutrality - regulation of Internet service providers (ISPs) to ensure equal treatment of all traffic - is becoming something many people have heard about. While the context is technical, network neutrality ultimately boils down to economics. The political weight of the subject is heavy, and the international debate is fierce. Still, surprisingly little rigorous research appears to be behind it. In this paper, I review economic literature on network neutrality and ISP regulation, covering both practical and theoretical implications for the broadband market. I define the degrees of network neutrality with more granularity than papers so far, evaluate the qualitative economic effects of regulation, and describe the broadband market, frameworks for modeling it, and its peculiar economic characteristics. In particular, I review and compare different theoretical modeling approaches and models' predictions of the welfare effects of different regulatory regimes. Throughout the paper, I incorporate economic literature from relevant areas into the analysis. I do not make definite policy recommendations, but I draw conclusions that are potentially of interest from a policy point of view. My analysis would indicate that the complexity of the Internet ecosystem and interrelations between market participants make effective regulation difficult. There is no economic evidence that network neutrality generally increases total welfare. In fact, it turns out that from a well-rounded economic perspective, strong network neutrality appears in most cases as detrimental to both consumer surplus and total welfare. In certain scenarios, however, models predict that neutrality can increase static and dynamic efficiency. The results depend crucially on model specifications and parameters, which differ significantly across the literature. So far, there is no consensus among economists on the optimal level of ISP regulation. Market-driven solutions such as dynamic pricing might provide a way to circumvent the neutrality question. Verkkoneutraliteetti - teleoperaattorien sääntely tietoliikenteen tasa-arvoisen kohtelun varmistamiseksi - on astunut käsitteenä julkisuuteen. Vaikka konteksti onkin tekninen, verkkoneutraliteetti viime kädessä redusoituu taloustieteeseen. Aiheen poliittinen painoarvo on suuri ja kansainvälinen keskustelu kiivasta. Tästä huolimatta sen takaa vaikuttaa löytyvän yllättävän vähän tieteellistä tutkimusta. Lopputyössäni tarkastelen taloustieteellistä kirjallisuutta verkkoneutraliteetista ja teleoperaattorien sääntelystä ja sen vaikutuksia laajakaistamarkkinaan käytännöllisestä kuin myös teoreettisesta näkökulmasta. Määrittelen verkkoneutraliteetin asteet hienojakoisemmin kuin aikaisemmat julkaisut, arvioin sääntelyn laadullisia vaikutuksia ja kuvailen laajakaistamarkkinaa, viitekehyksiä sen mallintamiseksi sekä sen eriskummallisia taloudellisia piirteitä. Kuvaan teoreettisia lähestymistapoja ja merkittävimpien mallien ennusteita sääntelymallien hyvinvointivaikutuksista. Liitän analyysini relevanttiin taloustieteelliseen kirjallisuuteen. En anna suoria politiikkasuosituksia, mutta teen johtopäätöksiä, jotka ovat mahdollisesti mielenkiintoisia poliittisesta näkökulmasta. Analyysini perusteella vaikuttaa, että Internet-ekosysteemin monimutkaisuus ja toimijoiden väliset suhteet tekevät tehokkaasta sääntelystä vaikeaa. Taloustieteellistä näyttöä verkkoneutraliteetin hyvinvointia kasvattavista vaikutuksista ei ole. Tasapainoisesta taloudellisesta näkökulmasta katsottuna tiukka neutraliteettisääntely näyttää useimmissa tapauksissa sekä pienentävän kuluttajan ylijäämää että laskevan kokonaishyvinvointia. Joissakin skenaarioissa mallit toisaalta ennustavat neutraliteetin lisäävän staattista ja dynaamista tehokkuutta. Tulokset riippuvat rajusti mallin rakenteesta ja parametreistä, jotka vaihtelevat merkittävästi tutkimuksesta tutkimukseen. Toistaiseksi taloustieteilijät eivät ole päässeet yhteisymmärrykseen optimaalisesta teleoperaattorien sääntelyn asteesta. Markkinalähtöiset ratkaisut kuten dynaaminen hinnoittelu saattavat mahdollistaa neutraliteettikysymyksen kiertämisen

Enhancing QoS provisioning and granularity in next generation internet

Next Generation IP technology has the potential to prevail, both in the access and in the core networks, as we are moving towards a multi-service, multimedia and high-speed networking environment. Many new applications, including the multimedia applications, have been developed and deployed, and demand Quality of Service (QoS) support from the Internet, in addition to the current best effort service. Therefore, QoS provisioning techniques in the Internet to guarantee some specific QoS parameters are more a requirement than a desire. Due to the large amount of data flows and bandwidth demand, as well as the various QoS requirements, scalability and fine granularity in QoS provisioning are required. In this dissertation, the end-to-end QoS provisioning mechanisms are mainly studied, in order to provide scalable services with fine granularity to the users, so that both users and network service providers can achieve more benefits from the QoS provisioned in the network. To provide the end-to-end QoS guarantee, single-node QoS provisioning schemes have to be deployed at each router, and therefore, in this dissertation, such schemes are studied prior to the study of the end-to-end QoS provisioning mechanisms. Specifically, the effective sharing of the output bandwidth among the large amount of data flows is studied, so that fairness in the bandwidth allocation among the flows can be achieved in a scalable fashion. A dual-rate grouping architecture is proposed in this dissertation, in which the granularity in rate allocation can be enhanced, while the scalability of the one-rate grouping architecture is still maintained. It is demonstrated that the dual-rate grouping architecture approximates the ideal per-flow based PFQ architecture better than the one-rate grouping architecture, and provides better immunity capability. On the end-to-end QoS provisioning, a new Endpoint Admission Control scheme for Diffserv networks, referred to as Explicit Endpoint Admission Control (EEAC), is proposed, in which the admission control decision is made by the end hosts based on the end-to-end performance of the network. A novel concept, namely the service vector, is introduced, by which an end host can choose different services at different routers along its data path. Thus, the proposed service provisioning paradigm decouples the end-to-end QoS provisioning from the service provisioning at each router, and the end-to-end QoS granularity in the Diffserv networks can be enhanced, while the implementation complexity of the Diffserv model is maintained. Furthermore, several aspects of the implementation of the EEAC and service vector paradigm, referred to as EEAC-SV, in the Diffserv architecture are also investigated. The performance analysis and simulation results demonstrate that the proposed EEAC-SV scheme, not only increases the benefit to the service users, but also enhances the benefit to the network service provider in terms of network resource utilization. The study also indicates that the proposed EEAC-SV scheme can provide a compatible and friendly networking environment to the conventional TCP flows, and the scheme can be deployed in the current Internet in an incremental and gradual fashion