Quality of Future Internet Services

This roadmap provides an outline of all the chapters of the book to help the reader find their way reading through this State of the Art report on Quality of future Internet Services. This we explain why the book is structured like this, what the logic is behind each chapter, and what the possible relations and dependencies between chapters are. At the end of the roadmap, we briefly outline the five-year history of the COST Action 263 that produced this book as its final report.

Quality of service in network communication is mainly assured by traffic management consisting in a variety of protocols and mechanisms whose role is to prevent the network from being congested. Traffic management has been a very active area of research for two decades following the conception of packet-switched integrated services networks, such as the Internet. This chapter provides samples of the state of the art in traffic management. It includes contributions on traffic theory, traffic and service models, quality monitoring, as well as traffic control and measurements.

Constraint-based routing is an invaluable part of a full- fledged Quality of Service architecture. Unfortunately, QoS routing with multiple additive constraints is known to be a NP-complete problem. Hence, accurate constraint-based routing algorithms with a fast running time are scarce, perhaps even non-existent. The need for such algorithms has resulted in the proposal of numerous heuristics and a few exact solutions.

This chapter presents a thorough, concise, and fair evaluation of the most important multi-constrained path selection algorithms known today. A performance evaluation of these algorithms is presented based on a complexity analysis and simulation results. Besides the routing algorithm, dynamic aspects of QoS routing are discussed: how to cope with incomplete or inaccurate topology information and (in)stability issues.

Traffic engineering encompasses a set of techniques that can be used to control the flow of traffic in data networks. We discuss several of those techniques that have been developed during the last few years. Some techniques are focused on pure IP networks while others have been designed with emerging technologies for scalable Quality of Service (QoS) such as Differentiated Services and MPLS in mind. We first discuss traffic engineering techniques inside a single domain. We show that by using a non-linear programming formulation of the traffic engineering problem it is possible to meet the requirements of demanding customer traffic, while optimising the use of network resources, through the means of an automated provisioning system. We also extend the functionality of the traffic engineering system through policies. In the following, we discuss the techniques that can be used to control the flow of packets between domains. First, we briefly describe interdomain routing and the Border Gateway Protocol (BGP). Second, we summarise the characteristics of interdomain traffic based on measurements with two different Internet Service Providers. We show by simulations the limitations of several BGP-based traffic engineering techniques that are currently used on the Internet. Then, we discuss the utilisation of BGP to exchange QoS information between domains by using the QOS_NLRI attribute to allow BGP to select more optimum paths. Finally, we consider the multi-homing problem and analyse the current proposed IPv6 multi-homing solutions are analysed along with their impact on communication quality.

We point out the different performance problems that need to be addressed when considering mobility in IP networks. We also define the reference architecture and present a framework to classify the different solutions for mobility management in IP networks. The performance of the major candidate micro-mobility solutions is evaluated for both real-time (UDP) and data (TCP) traffic through simulation and by means of an analytical model. Using these models we compare the performance of different mobility management schemes for different data and real-time services and the network resources that are needed for it. We point out the problems of TCP in wireless environments and review some proposed enhancements to TCP that aim at improving TCP performance. We make a detailed study of how some of micro-mobility protocols namely Cellular IP, Hawaii and Hierarchical Mobile IP affect the behavior of TCP and their interaction with the MAC layer. We investigate the impact of handoffs on TCP by means of simulation traces that show the evolution of segments and acknowledgments during handoffs.

In this chapter, we address how to achieve scalable content distributions. We present two contributions, each of which uses a different approach to distribute the content.

In the first part of this chapter, we consider a terrestrial overlay network and build on top of it a VoD service for fixed clients. The goal is to minimize the operational cost of the service. Our contibutions are as follows. First, we introduce a new video distribution architecture that combines open-loop and closed-loop schemes. This combination makes the overall system highly scalable, very cost-effective, and ensures a zero start-up delay. Our second contribution is a mathematical model for the cost of delivering a video as a function of the popularity of that video. Our analytical model, along with some extensions, allows us to explore several scenarios: (i) long videos of 90 min (movies), (ii) short videos of a few min (clips), (iii) the dimensioning of a video on demand service from scratch, and (iv) the case of the optimization of an already installed video on demand service (i.e. the limited resources scenario).

In the second part of this chapter, we consider a satellite distribution of contents to mobile users, or in general to users thar are occasionally connected. We consider a push-based model, where the server periodically downloads objects. We assume that clients register to the service off-line. Our goal is to minimize the mean aggregate reception delay over all objects where each object is weighted by its popularity. Our contibutions in this part are as follows. First, we provide a simple proof for the need of periodicity (equal distance in transmission) of popular objects in a cycle. Second, in contrast to existing results, we consider the scheduling problem for caching clients. To increase the performance of the system, we also evaluate a pre-emptive scheduling algorithm that allows interruption (pre-emption) of an object’s transmission in order to transmit on schedule another more popular one.

In this chapter the state of the art of pricing for Internet services and its relation to Quality-of-Service (QoS) is addressed. Essential economic and technology basics, covering terms, accounting, and security are followed by a user-centered view, a content-based scheme, and a cost sharing approach.